1.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
2.
ChEMBL
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ChEMBL or ChEMBLdb is a manually curated chemical database of bioactive molecules with drug-like properties. It is maintained by the European Bioinformatics Institute, of the European Molecular Biology Laboratory, based at the Wellcome Trust Genome Campus, Hinxton, the database, originally known as StARlite, was developed by a biotechnology company called Inpharmatica Ltd. later acquired by Galapagos NV. The data was acquired for EMBL in 2008 with an award from The Wellcome Trust, resulting in the creation of the ChEMBL chemogenomics group at EMBL-EBI, the ChEMBL database contains compound bioactivity data against drug targets. Bioactivity is reported in Ki, Kd, IC50, and EC50, data can be filtered and analyzed to develop compound screening libraries for lead identification during drug discovery. ChEMBL version 2 was launched in January 2010, including 2.4 million bioassay measurements covering 622,824 compounds and this was obtained from curating over 34,000 publications across twelve medicinal chemistry journals. ChEMBLs coverage of available bioactivity data has grown to become the most comprehensive ever seen in a public database, in October 2010 ChEMBL version 8 was launched, with over 2.97 million bioassay measurements covering 636,269 compounds. ChEMBL_10 saw the addition of the PubChem confirmatory assays, in order to integrate data that is comparable to the type, ChEMBLdb can be accessed via a web interface or downloaded by File Transfer Protocol. It is formatted in a manner amenable to computerized data mining, ChEMBL is also integrated into other large-scale chemistry resources, including PubChem and the ChemSpider system of the Royal Society of Chemistry. In addition to the database, the ChEMBL group have developed tools and these include Kinase SARfari, an integrated chemogenomics workbench focussed on kinases. The system incorporates and links sequence, structure, compounds and screening data, the primary purpose of ChEMBL-NTD is to provide a freely accessible and permanent archive and distribution centre for deposited data. July 2012 saw the release of a new data service, sponsored by the Medicines for Malaria Venture. The data in this service includes compounds from the Malaria Box screening set, myChEMBL, the ChEMBL virtual machine, was released in October 2013 to allow users to access a complete and free, easy-to-install cheminformatics infrastructure. In December 2013, the operations of the SureChem patent informatics database were transferred to EMBL-EBI, in a portmanteau, SureChem was renamed SureChEMBL. 2014 saw the introduction of the new resource ADME SARfari - a tool for predicting and comparing cross-species ADME targets
3.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses
4.
European Chemicals Agency
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ECHA is the driving force among regulatory authorities in implementing the EUs chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and it is located in Helsinki, Finland. The Agency, headed by Executive Director Geert Dancet, started working on 1 June 2007, the REACH Regulation requires companies to provide information on the hazards, risks and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most commonly used substances have been registered, the information is technical but gives detail on the impact of each chemical on people and the environment. This also gives European consumers the right to ask whether the goods they buy contain dangerous substances. The Classification, Labelling and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU. This worldwide system makes it easier for workers and consumers to know the effects of chemicals, companies need to notify ECHA of the classification and labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100000 substances, the information is freely available on their website. Consumers can check chemicals in the products they use, Biocidal products include, for example, insect repellents and disinfectants used in hospitals. The Biocidal Products Regulation ensures that there is information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation, the law on Prior Informed Consent sets guidelines for the export and import of hazardous chemicals. Through this mechanism, countries due to hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have effects on human health and the environment are identified as Substances of Very High Concern 1. These are mainly substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment, other substances considered as SVHCs include, for example, endocrine disrupting chemicals. Companies manufacturing or importing articles containing these substances in a concentration above 0 and they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy, once a substance has been officially identified in the EU as being of very high concern, it will be added to a list. This list is available on ECHA’s website and shows consumers and industry which chemicals are identified as SVHCs, Substances placed on the Candidate List can then move to another list
5.
PubChem
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PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds, more than 80 database vendors contribute to the growing PubChem database. PubChem consists of three dynamically growing primary databases, as of 28 January 2016, Compounds,82.6 million entries, contains pure and characterized chemical compounds. Substances,198 million entries, contains also mixtures, extracts, complexes, bioAssay, bioactivity results from 1.1 million high-throughput screening programs with several million values. PubChem contains its own online molecule editor with SMILES/SMARTS and InChI support that allows the import and export of all common chemical file formats to search for structures and fragments. In the text search form the database fields can be searched by adding the name in square brackets to the search term. A numeric range is represented by two separated by a colon. The search terms and field names are case-insensitive, parentheses and the logical operators AND, OR, and NOT can be used. AND is assumed if no operator is used, example,0,5000,50,10 -5,5 PubChem was released in 2004. The American Chemical Society has raised concerns about the publicly supported PubChem database and they have a strong interest in the issue since the Chemical Abstracts Service generates a large percentage of the societys revenue. To advocate their position against the PubChem database, ACS has actively lobbied the US Congress, soon after PubChems creation, the American Chemical Society lobbied U. S. Congress to restrict the operation of PubChem, which they asserted competes with their Chemical Abstracts Service
6.
International Chemical Identifier
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Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure
7.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES
8.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
9.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
10.
Aqueous solution
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An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant chemical formula, for example, a solution of table salt, or sodium chloride, in water would be represented as Na+ + Cl−. The word aqueous means pertaining to, related to, similar to, as water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Substances that are hydrophobic often do not dissolve well in water, an example of a hydrophilic substance is sodium chloride. Acids and bases are aqueous solutions, as part of their Arrhenius definitions, the ability of a substance to dissolve in water is determined by whether the substance can match or exceed the strong attractive forces that water molecules generate between themselves. If the substance lacks the ability to dissolve in water the molecules form a precipitate, reactions in aqueous solutions are usually metathesis reactions. Metathesis reactions are another term for double-displacement, that is, when a cation displaces to form a bond with the other anion. The cation bonded with the latter anion will dissociate and bond with the other anion, aqueous solutions that conduct electric current efficiently contain strong electrolytes, while ones that conduct poorly are considered to have weak electrolytes. Those strong electrolytes are substances that are ionized in water. Nonelectrolytes are substances that dissolve in water yet maintain their molecular integrity, examples include sugar, urea, glycerol, and methylsulfonylmethane. When writing the equations of reactions, it is essential to determine the precipitate. To determine the precipitate, one must consult a chart of solubility, soluble compounds are aqueous, while insoluble compounds are the precipitate. Remember that there may not always be a precipitate, when performing calculations regarding the reacting of one or more aqueous solutions, in general one must know the concentration, or molarity, of the aqueous solutions. Solution concentration is given in terms of the form of the prior to it dissolving. Metal ions in aqueous solution Solubility Dissociation Acid-base reaction theories Properties of water Zumdahl S.1997, 4th ed. Boston, Houghton Mifflin Company
11.
Solubility
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Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent. The solubility of a substance depends on the physical and chemical properties of the solute and solvent as well as on temperature, pressure. The solubility of a substance is a different property from the rate of solution. Most often, the solvent is a liquid, which can be a substance or a mixture. One may also speak of solid solution, but rarely of solution in a gas, the extent of solubility ranges widely, from infinitely soluble such as ethanol in water, to poorly soluble, such as silver chloride in water. The term insoluble is often applied to poorly or very poorly soluble compounds, a common threshold to describe something as insoluble is less than 0.1 g per 100 mL of solvent. Under certain conditions, the solubility can be exceeded to give a so-called supersaturated solution. Metastability of crystals can also lead to apparent differences in the amount of a chemical that dissolves depending on its form or particle size. A supersaturated solution generally crystallises when seed crystals are introduced and rapid equilibration occurs, phenylsalicylate is one such simple observable substance when fully melted and then cooled below its fusion point. Solubility is not to be confused with the ability to dissolve a substance, for example, zinc dissolves in hydrochloric acid as a result of a chemical reaction releasing hydrogen gas in a displacement reaction. The zinc ions are soluble in the acid, the smaller a particle is, the faster it dissolves although there are many factors to add to this generalization. Crucially solubility applies to all areas of chemistry, geochemistry, inorganic, physical, organic, in all cases it will depend on the physical conditions and the enthalpy and entropy directly relating to the solvents and solutes concerned. By far the most common solvent in chemistry is water which is a solvent for most ionic compounds as well as a range of organic substances. This is a factor in acidity/alkalinity and much environmental and geochemical work. According to the IUPAC definition, solubility is the composition of a saturated solution expressed as a proportion of a designated solute in a designated solvent. Solubility may be stated in units of concentration such as molarity, molality, mole fraction, mole ratio, mass per volume. Solubility occurs under dynamic equilibrium, which means that solubility results from the simultaneous and opposing processes of dissolution, the solubility equilibrium occurs when the two processes proceed at a constant rate. The term solubility is used in some fields where the solute is altered by solvolysis
12.
Alcohol
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In chemistry, an alcohol is any organic compound in which the hydroxyl functional group is bound to a saturated carbon atom. The term alcohol originally referred to the alcohol ethanol, the predominant alcohol in alcoholic beverages. The suffix -ol in non-systematic names also typically indicates that the substance includes a functional group and, so. But many substances, particularly sugars contain hydroxyl functional groups without using the suffix, an important class of alcohols, of which methanol and ethanol are the simplest members is the saturated straight chain alcohols, the general formula for which is CnH2n+1OH. The word alcohol is from the Arabic kohl, a used as an eyeliner. Al- is the Arabic definite article, equivalent to the in English, alcohol was originally used for the very fine powder produced by the sublimation of the natural mineral stibnite to form antimony trisulfide Sb 2S3, hence the essence or spirit of this substance. It was used as an antiseptic, eyeliner, and cosmetic, the meaning of alcohol was extended to distilled substances in general, and then narrowed to ethanol, when spirits as a synonym for hard liquor. Bartholomew Traheron, in his 1543 translation of John of Vigo, Vigo wrote, the barbarous auctours use alcohol, or alcofoll, for moost fine poudre. The 1657 Lexicon Chymicum, by William Johnson glosses the word as antimonium sive stibium, by extension, the word came to refer to any fluid obtained by distillation, including alcohol of wine, the distilled essence of wine. Libavius in Alchymia refers to vini alcohol vel vinum alcalisatum, Johnson glosses alcohol vini as quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat. The words meaning became restricted to spirit of wine in the 18th century and was extended to the class of substances so-called as alcohols in modern chemistry after 1850, the term ethanol was invented 1892, based on combining the word ethane with ol the last part of alcohol. In the IUPAC system, in naming simple alcohols, the name of the alkane chain loses the terminal e and adds ol, e. g. as in methanol and ethanol. When necessary, the position of the group is indicated by a number between the alkane name and the ol, propan-1-ol for CH 3CH 2CH 2OH, propan-2-ol for CH 3CHCH3. If a higher priority group is present, then the prefix hydroxy is used, in other less formal contexts, an alcohol is often called with the name of the corresponding alkyl group followed by the word alcohol, e. g. methyl alcohol, ethyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol, depending on whether the group is bonded to the end or middle carbon on the straight propane chain. As described under systematic naming, if another group on the molecule takes priority, Alcohols are then classified into primary, secondary, and tertiary, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl functional group. The primary alcohols have general formulas RCH2OH, the simplest primary alcohol is methanol, for which R=H, and the next is ethanol, for which R=CH3, the methyl group. Secondary alcohols are those of the form RRCHOH, the simplest of which is 2-propanol, for the tertiary alcohols the general form is RRRCOH
13.
Salt (chemistry)
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In chemistry, a salt is an ionic compound that results from the neutralization reaction of an acid and a base. Salts are composed of related numbers of cations and anions so that the product is electrically neutral and these component ions can be inorganic, such as chloride, or organic, such as acetate, and can be monatomic, such as fluoride, or polyatomic, such as sulfate. There are several varieties of salts, salts that hydrolyze to produce hydroxide ions when dissolved in water are alkali salts, whilst those that hydrolyze to produce hydronium ions in water are acidic salts. Neutral salts are those salts that are neither acidic nor basic, zwitterions contain an anionic centre and a cationic centre in the same molecule, but are not considered to be salts. Examples of zwitterions include amino acids, many metabolites, peptides, usually, non-dissolved salts at standard conditions for temperature and pressure are solid, but there are exceptions. Molten salts and solutions containing dissolved salts are called electrolytes, as they are able to conduct electricity. As observed in the cytoplasm of cells, in blood, urine, plant saps and mineral waters, therefore, their salt content is given for the respective ions. Salts can appear to be clear and transparent, opaque, and even metallic, in many cases, the apparent opacity or transparency are only related to the difference in size of the individual monocrystals. Since light reflects from the boundaries, larger crystals tend to be transparent. The color of the salt is due to the electronic structure in the d-orbitals of transition elements or in the conjugated organic dye framework. Different salts can elicit all five basic tastes, e. g. salty, sweet, sour, bitter, and umami or savory. Salts of strong acids and strong bases are non-volatile and odorless and that slow, partial decomposition is usually accelerated by the presence of water, since hydrolysis is the other half of the reversible reaction equation of formation of weak salts. Many ionic compounds can be dissolved in water or other similar solvents, the exact combination of ions involved makes each compound have a unique solubility in any solvent. The solubility is dependent on how well each ion interacts with the solvent, for example, all salts of sodium, potassium and ammonium are soluble in water, as are all nitrates and many sulfates – barium sulfate, calcium sulfate and lead sulfate are examples of exceptions. However, ions that bind tightly to each other and form highly stable lattices are less soluble, for example, most carbonate salts are not soluble in water, such as lead carbonate and barium carbonate. Some soluble carbonate salts are, sodium carbonate, potassium carbonate, solid salts do not conduct electricity. Moreover, solutions of salts also conduct electricity, the name of a salt starts with the name of the cation followed by the name of the anion. Salts are often referred to only by the name of the cation or by the name of the anion. g
14.
Iron
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Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
15.
Ion
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An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by chemical or physical means. In chemical terms, if an atom loses one or more electrons. If an atom gains electrons, it has a net charge and is known as an anion. Ions consisting of only a single atom are atomic or monatomic ions, because of their electric charges, cations and anions attract each other and readily form ionic compounds, such as salts. In the case of ionization of a medium, such as a gas, which are known as ion pairs are created by ion impact, and each pair consists of a free electron. The word ion comes from the Greek word ἰόν, ion, going and this term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium. Faraday also introduced the words anion for a charged ion. In Faradays nomenclature, cations were named because they were attracted to the cathode in a galvanic device, arrhenius explanation was that in forming a solution, the salt dissociates into Faradays ions. Arrhenius proposed that ions formed even in the absence of an electric current, ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, lightning, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of charge to give neutral molecules or ionic salts. These stabilized species are commonly found in the environment at low temperatures. A common example is the present in seawater, which are derived from the dissolved salts. Electrons, due to their mass and thus larger space-filling properties as matter waves, determine the size of atoms. Thus, anions are larger than the parent molecule or atom, as the excess electron repel each other, as such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation contains no electrons, and thus consists of a single proton - very much smaller than the parent hydrogen atom. Since the electric charge on a proton is equal in magnitude to the charge on an electron, an anion, from the Greek word ἄνω, meaning up, is an ion with more electrons than protons, giving it a net negative charge. A cation, from the Greek word κατά, meaning down, is an ion with fewer electrons than protons, there are additional names used for ions with multiple charges
16.
Ferrous
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Ferrous, in chemistry, indicates a divalent iron compound, as opposed to ferric, which indicates a trivalent iron compound. Outside chemistry, ferrous is a used to indicate the presence of iron. The word is derived from the Latin word ferrum, Ferrous metals include steel and pig iron and alloys of iron with other metals. Manipulation of atom-to-atom relationships between iron, carbon, and various alloying elements establishes the specific properties of ferrous metals, the term non-ferrous is used to indicate metals other than iron and alloys that do not contain an appreciable amount of iron. Ferromagnetism Steelmaking Ferrous metal recycling Iron oxide Ferrous chloride Iron bromide
17.
Citric acid
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Citric acid is a weak organic tricarboxylic acid having the chemical formula C6H8O7. It occurs naturally in citrus fruits, in biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. More than a million tons of acid are manufactured every year. It is used widely as an acidifier, as a flavoring and chelating agent, a citrate is a derivative of citric acid, that is, the salts, esters, and the polyatomic anion found in solution. An example of the former, a salt is trisodium citrate, when part of a salt, the formula of the citrate ion is written as C6H5O73− or C3H5O33−. Citric acid exists in greater than trace amounts in a variety of fruits and vegetables, lemons and limes have particularly high concentrations of the acid, it can constitute as much as 8% of the dry weight of these fruits. The concentrations of acid in citrus fruits range from 0.005 mol/L for oranges and grapefruits to 0.30 mol/L in lemons. Within species, these values vary depending on the cultivar and the circumstances in which the fruit was grown, wehmer discovered Penicillium mold could produce citric acid from sugar. However, microbial production of citric acid did not become important until World War I disrupted Italian citrus exports. In this production technique, which is still the major route to citric acid used today. The source of sugar is corn steep liquor, molasses, hydrolyzed corn starch or other inexpensive sugary solutions, in 1977, a patent was granted to Lever Brothers for the chemical synthesis of citric acid starting either from aconitic or isocitrate/alloisocitrate calcium salts under high pressure conditions. This produced citric acid in near quantitative conversion under what appeared to be a reverse non-enzymatic Krebs cycle reaction, in 2007, worldwide annual production stood at approximately 1,600,000 tons. More than 50% of this volume was produced in China, citric acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice. It can exist either in a form or as a monohydrate. The anhydrous form crystallizes from hot water, while the forms when citric acid is crystallized from cold water. The monohydrate can be converted to the form at about 78 °C. Citric acid also dissolves in ethanol at 15 °C. It decomposes with loss of carbon dioxide above about 175 °C, citric acid is normally considered to be a tribasic acid, with pKa values, extrapolated to zero ionic strength, of 5.21,4.28 and 2.92 at 25 °C
18.
Disodium citrate
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Disodium citrate, more properly, disodium hydrogen citrate, is an acid salt of citric acid with the chemical formula Na2C6H6O7. It is used as an antioxidant in food as well as to improve the effects of other antioxidants and it is also used as an acidity regulator and sequestrant. Typical products include gelatin, jam, sweets, ice cream, carbonated beverages, milk powder, wine, disodium citrate may be used in patients to alleviate discomfort from urinary tract infections
19.
Iron(II) sulfate
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Iron sulfate or ferrous sulfate denotes a range of salts with the formula FeSO4·xH2O. These compounds exist most commonly as the heptahydrate but are known for several values of x, the hydrated form is used medically to treat iron deficiency, and also for industrial applications. Known since ancient times as copperas and as green vitriol, the blue-green heptahydrate is the most common form of this material, all the iron sulfates dissolve in water to give the same aquo complex 2+, which has octahedral molecular geometry and is paramagnetic. The name copperas dates from times when the copper sulfate was known as blue copperas and it is on the World Health Organizations List of Essential Medicines, the most important medications needed in a basic health system. Industrially, ferrous sulfate is used as a precursor to other iron compounds. It is an agent, and as such is useful for the reduction of chromate in cement to less toxic Cr compounds. Historically ferrous sulfate was used in the industry for centuries as a dye fixative. It is used historically to blacken leather and as a constituent of ink, together with other iron compounds, ferrous sulfate is used to fortify foods and to treat and prevent iron deficiency anemia. Constipation is a frequent and uncomfortable side effect associated with the administration of oral iron supplements, stool softeners often are prescribed to prevent constipation. Ferrous sulfate was used in the manufacture of inks, most notably iron gall ink, chemical tests made on the Lachish letters showed the possible presence of iron. It is thought that oak galls and copperas may have used in making the ink on those letters. It also finds use in dyeing as a mordant. Harewood, a used in marquetry and parquetry since the 17th century, is also made using ferrous sulfate. Two different methods for the application of indigo dye were developed in England in the eighteenth century. One of these, known as blue, involved iron sulfate. After printing an insoluble form of indigo onto the fabric, the indigo was reduced to leuco-indigo in a sequence of baths of ferrous sulfate, the china blue process could make sharp designs, but it could not produce the dark hues of other methods. Sometimes, it is included in canned black olives as an artificial colorant, ferrous sulfate can also be used to stain concrete and some limestones and sandstones a yellowish rust color. Woodworkers use ferrous sulfate solutions to color maple wood a silvery hue, in horticulture it is used for treating iron chlorosis
20.
Water of crystallization
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In chemistry, water of crystallization or water of hydration or crystallization water is water that occurs inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions, in some contexts, water of crystallization is the total weight of water in a substance at a given temperature and is mostly present in a definite ratio. Classically, water of crystallization refers to water that is found in the framework of a metal complex or a salt. Upon crystallization from water or moist solvents, many compounds incorporate water molecules in their crystalline frameworks, water of crystallization can generally be removed by heating a sample but the crystalline properties are often lost. For example, in the case of chloride, the dihydrate is unstable at room temperature. Compared to inorganic salts, proteins crystallize with large amounts of water in the crystal lattice, the water content of 50% is not uncommon for proteins. For example Calcium chloride, CaCl2·2H2O hydrated compoundn A hydrate with coordinated water, for example Zinc chloride, ZnCl24 Both notations can be combined as for example in copper sulfate, SO4·H2O A salt with associated water of crystallization is known as a hydrate. The structure of hydrates can be elaborate, because of the existence of hydrogen bonds that define polymeric structures. Historically, the structures of many hydrates were unknown, and the dot in the formula of a hydrate was employed to specify the composition without indicating how the water is bound, for example, an aqueous solution prepared from CuSO4•5H2O and anhydrous CuSO4 behave identically. Therefore, knowledge of the degree of hydration is important only for determining the equivalent weight, in some cases, the degree of hydration can be critical to the resulting chemical properties. For example, anhydrous RhCl3 is not soluble in water and is useless in organometallic chemistry whereas RhCl3•3H2O is versatile. Similarly, hydrated AlCl3 is a poor Lewis acid and thus inactive as a catalyst for Friedel-Crafts reactions, samples of AlCl3 must therefore be protected from atmospheric moisture to preclude the formation of hydrates. Crystals of the aforementioned hydrated copper sulfate consist of 2+ centers linked to SO42− ions, copper is surrounded by six oxygen atoms, provided by two different sulfate groups and four molecules of water. A fifth water resides elsewhere in the framework but does not bind directly to copper, the cobalt chloride mentioned above occurs as 2+ and Cl−. In tin chloride, each Sn center is pyramidal being bound to two chloride ions and one water, the second water in the formula unit is hydrogen-bonded to the chloride and to the coordinated water molecule. Water of crystallization is stabilized by electrostatic attractions, consequently hydrates are common for salts that contain +2, in some cases, the majority of the weight of a compound arises from water. Glaubers salt, Na2SO410, is a crystalline solid with greater than 50% water by weight. Consider the case of nickel chloride hexahydrate and this species has the formula NiCl26
21.
Dietary supplement
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A dietary supplement is intended to provide nutrients that may otherwise not be consumed in sufficient quantities. Supplements as generally understood include vitamins, minerals, fiber, fatty acids, or amino acids, U. S. authorities define dietary supplements as foods, while elsewhere they may be classified as drugs or other products. There are more than 50,000 dietary supplements available, more than half of the U. S. adult population consume dietary supplements with most common ones being multivitamins. These products are not intended to prevent or treat any disease and in some circumstances are dangerous, for those who fail to consume a balanced diet, the agency says that certain supplements may have value. Most supplements should be avoided, and usually people should not eat micronutrients except people with clearly shown deficiency and those people should first consult a doctor. An exception is vitamin D, which is recommended in Nordic countries due to weak sunlight, the product is labeled as a dietary supplement. In the United States, the FDA has different monitoring procedures for substances depending on whether they are presented as drugs, food additives, food, or dietary supplements. Dietary supplements are eaten or taken by mouth, and are regulated in United States law as a type of rather than a type of drug. The intended use of dietary supplements is to ensure that a person gets enough essential nutrients, Dietary supplements should not be used to treat any disease or as preventive healthcare. An exception to this recommendation is the use of vitamins. Supplements may create harm in several ways, including over-consumption, particularly of minerals, the products may also cause harm related to their rapid absorption in a short period of time, quality issues such as contamination, or by adverse interactions with other foods and medications. There are many types of dietary supplements, Vitamin is an organic compound required by an organism as a vital nutrient in limited amounts. An organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, thus, the term is conditional both on the circumstances and on the particular organism. For example, ascorbic acid is a vitamin for humans, supplementation is important for the treatment of certain health problems but there is little evidence of benefit when used by those who are otherwise healthy. Amino acids are biologically important organic compounds composed of amine and carboxylic acid functional groups, the key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. Amino acids can be divided into three categories, essential amino acids, non-essential amino acids, and conditional amino acids, essential amino acids cannot be made by the body, and must be supplied by food. Non-essential amino acids are made by the body from essential amino acids or in the breakdown of proteins. Conditional amino acids are not essential, except in times of illness, stress
22.
Boca Raton, Florida
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Boca Raton is the southernmost city in Palm Beach County, Florida, United States, first incorporated on August 2,1924 as Bocaratone, and then incorporated as Boca Raton in 1925. The 2015 population estimated by the U. S. Census Bureau was 93,235, however, approximately 200,000 people with a Boca Raton postal address reside outside its municipal boundaries. Such areas include newer developments like West Boca Raton, as a business center, the city also experiences significant daytime population increases. It is one of the wealthiest communities in South Florida, Boca Raton is located 43 miles north of Miami and is a principal city of the Miami metropolitan area, which was home to an estimated 6,012,331 people at the 2015 census. Boca Raton is home to the campus of Florida Atlantic University and the corporate headquarters of Office Depot, ADT. It is also home to the Evert Tennis Academy, owned by tennis player Chris Evert. Town Center Mall, a shopping center in West Boca Raton, is the largest indoor mall in Palm Beach County. Another major attraction to the area is Boca Ratons downtown, known as Mizner Park, still today, Boca Raton has a strict development code for the size and types of commercial buildings, building signs, and advertisements that may be erected within the city limits. No outdoor car dealerships are allowed in the municipality, additionally, no billboards are permitted, the citys only billboard was grandfathered in during annexation. The strict development code has led to major thoroughfares without large signs or advertisements in the travelers view. The original name Boca de Ratones appeared on eighteenth-century maps associated with an inlet in the Biscayne Bay area of Miami. The word ratones appears in old Spanish maritime dictionaries referring to rugged rocks or stony ground on the bottom of some ports and coastal outlets, therefore, the abridged translation defining Boca de Ratones is a shallow inlet of sharp-pointed rocks which scrape a ships cables. Residents of the city have kept the pronunciation of Boca Raton similar to its Spanish origins, in particular, the Raton in Boca Raton is pronounced as /rəˈtoʊn/ instead of /rəˈtɑːn/. The latter is a common mispronunciation by non-natives to the region, the area today known as Boca Raton was originally occupied by the Tequesta tribe, a Native American people that occupied an area along the southeastern Atlantic coast of Florida. What Spanish voyagers called Boca de Ratones was originally located to the south, by mistake since the 19th century, mapmakers moved this location to the north and began referring to the citys lake, today known as Lake Boca Raton, as Boca Ratone Sounde. The area was largely uninhabited after the Indigenous people were cleared from the area by the Spanish and he surveyed and sold land from the canal to beyond the railroad north of what is now Palmetto Park Road. Early settlement in the area increased shortly after Henry Flaglers expansion of the Florida East Coast Railway, in the citys early history during the Florida land boom of the 1920s, several investors were interested in turning Boca Raton into a resort town. Most famously, Addison Mizner had several projects for resorts and mansions in the area and he first constructed his Administrative Buildings and a small hotel to house interested investors
23.
CRC Press
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The CRC Press, LLC is a publishing group based in the United States that specializes in producing technical books. Many of their books relate to engineering, science and mathematics and their scope also includes books on business, forensics and information technology. CRC Press is now a division of Taylor & Francis, itself a subsidiary of Informa, the company gradually expanded to include sales of laboratory equipment to chemists. In 1913 the CRC offered a manual called the Rubber Handbook as an incentive for any purchase of a dozen aprons. Since then the Rubber Handbook has evolved into the CRCs flagship book, in 1986 CRC Press was bought by the Times Mirror Company. Times Mirror began exploring the possibility of a sale of CRC Press in 1996, in 2003, CRC became part of Taylor & Francis, which in 2004 became part of the UK publisher Informa. Chapman & Hall CRC Press website
24.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
25.
Disodium tetracarbonylferrate
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Disodium tetracarbonylferrate is the organometallic compound with the formula Na2. This oxygen-sensitive colourless solid is employed in synthesis, mainly to synthesise aldehydes. It is commonly used with dioxane complexed to the sodium cation, the reagent was reported by Cooke in 1970. The current synthesis entails the reduction of a solution of iron pentacarbonyl in tetrahydrofuran by sodium naphthenide, the efficiency of the synthesis depends on the quality of the iron pentacarbonyl. Fe5 + Na-Hg +THF → Na2 Fe5 + Na + Dioxane + PhCOPh → Na2 Fe5 + Na/PhCOPh + THF → Na2 Another way to synthesize Collmans Reagent is to use FeCl3. FeCl3 + Na + 4CO + THF → +Na → Na2 These synthesis pathways are extremely useful in preparing Collmans Reagent if the typical reagents to make it are not available, Disodium tetracarbonylferrate can be used to convert acid chlorides to aldehydes. As for Cooke’s early discovery, an acyl complex undergoes protonolysis to give the aldehyde. Collman, J. P. Disodium Tetracarbonylferrate, a Transition Metal Analog of a Grignard Reagent, Disodium Tetracarbonylferrate, A Reagent for Acid Functionalization of Halogenated Polymers. Hieber, V. W. Braun, G. Zeitschrift für Naturforschung B
26.
Iron pentacarbonyl
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Iron pentacarbonyl, also known as iron carbonyl, is the compound with formula Fe5. Under standard conditions Fe5 is a free-flowing, straw-colored liquid with a pungent odour and this compound is a common precursor to diverse iron compounds, including many that are useful in small scale organic synthesis. Iron pentacarbonyl is a metal carbonyl, where carbon monoxide is the only ligand complexed with a metal. Other examples include octahedral Cr6 and tetrahedral Ni4, most metal carbonyls have 18 valence electrons, and Fe5 fits this pattern with 8 valence electrons on Fe and five pairs of electrons provided by the CO ligands. Reflecting its symmetrical structure and charge neutrality, Fe5 is volatile, Fe5 adopts a trigonal bipyramidal structure with the Fe atom surrounded by five CO ligands, three in equatorial positions and two axially bound. The Fe–C–O linkages are each linear, Fe5 exhibits a relatively low rate of interchange between the axial and equatorial CO groups via the Berry mechanism. Iron carbonyl is sometimes confused with carbonyl iron, a high-purity metal prepared by decomposition of iron pentacarbonyl, Fe5 is produced by the reaction of fine iron particles with carbon monoxide. The compound was described in a journal by Mond and Langer in 1891 as a viscous liquid of a pale-yellow colour. Samples were prepared by treatment of finely divided, oxide-free iron powder with carbon monoxide at room temperature, industrial synthesis of the compound requires relatively high temperatures and pressures as well as special, chemically resistant equipment. Preparation of the compound at the laboratory scale avoids these complications by using an iodide intermediate, photodissociation of Fe5 produces Fe29, a yellow-orange solid, also described by Mond. When heated, Fe5 converts to small amounts of the metal cluster Fe312, simple thermolysis, however, is not a useful synthesis, and each iron carbonyl complex exhibits distinct reactivity. The industrial production of compound is somewhat similar to the Mond process in that the metal is treated with carbon monoxide to give a volatile gas. In the case of iron pentacarbonyl, the reaction is more sluggish and it is necessary to use iron sponge as the starting material, and harsher reaction conditions of 5–30 MPa of carbon monoxide and 150–200 °C. Similar to the Mond process, sulfur acts as a catalyst, the crude iron pentacarbonyl is purified by distillation. Most iron pentacarbonyl produced is decomposed on site to give pure iron in analogy to carbonyl nickel. Some iron pentacarbonyl is burned to give pure iron oxide, other uses of pentacarbonyliron are small in comparison. Many compounds are derived from Fe5 by substitution of CO by Lewis bases, L, common Lewis bases include isocyanides, tertiary phosphines and arsines, and alkenes. Usually these ligands displace only one or two CO ligands, but certain acceptor ligands such as PF3 and isocyanides can proceed to tetra- and these reactions are often induced with a catalyst or light
27.
Diiron nonacarbonyl
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Diiron nonacarbonyl is an inorganic compound with the formula Fe29. This metal carbonyl is an important reagent in chemistry and of occasional use in organic synthesis. It is a reactive source of Fe than Fe5 and less dangerous to handle because it is nonvolatile. This micaceous orange solid is insoluble in all common solvents. Following the original method, photolysis of an acid solution of Fe5 produces Fe29 in good yield,2 Fe5 → Fe29 + CO Fe29 consists of a pair of Fe3 centers linked by three bridging CO ligands. The minor isomer has been crystallized together with C60, the iron atoms are equivalent and octahedral molecular geometry. Elucidation of the structure of Fe29 proved to be challenging because its low solubility inhibits growth of crystals, the Mößbauer spectrum reveals one quadrupole doublet, consistent with the D3h-symmetric structure. Fe29 is a precursor to compounds of the type Fe4L and Fe3, such syntheses are typically conducted in THF solution. In these conversions, it is proposed that small amounts of Fe29 dissolve according to the following reaction, Fe29 has also been employed in the synthesis of cyclopentadienones via a net -cycloaddition from dibromoketones, known as the Noyori reaction. Low temperature UV/vis photolysis of Fe29 yields the Fe28 unsaturated complex, producing both CO-bridged and unbridged isomers
28.
Triiron dodecacarbonyl
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Triiron dodecarbonyl is the organoiron compound with the formula Fe312. It is a green solid that sublimes under vacuum. It is soluble in organic solvents to give intensely green solutions. Most low-nuclearity clusters are pale yellow or orange, hot solutions of Fe312 decompose to an iron mirror, which can be pyrophoric in air. The solid decomposes slowly in air, and thus samples are typically stored cold under an inert atmosphere and it is a more reactive source of iron than iron pentacarbonyl. It was one of the first metal carbonyl clusters synthesized and it was occasionally obtained from the thermolysis of Fe5,3 Fe5 → Fe312 +3 CO Traces of the compound are easily detected because of its characteristic deep green colour. UV-photolysis of Fe5 produces Fe29, not Fe312, entailed the oxidation of H2Fe4 with MnO2. The cluster was originally formulated incorrectly as Fe4, elucidation of the structure of Fe312 proved to be challenging because the CO ligands are disordered in the crystals. Fe312 consists of a triangle of iron surrounded by 12 CO ligands. Ten of the CO ligands are terminal and two span an Fe---Fe edge, resulting in C2v point group symmetry, by contrast, Ru312 and Os312 adopt D3h-symmetric structures, wherein all 12 CO ligands are terminally bound to the metals. Spectroscopic evidence indicates that the two groups may be unsymmetrical, in which case the idealized C2v symmetry is reduced to C2. In solution Fe312 is fluxional, resulting in equivalencing all 12 CO groups, the anion − is structurally related to Fe312, with the hydride replacing one bridging CO ligand. The bonding in the Fe-H-Fe subunit is described using concepts developed for diborane, like most metal carbonyls, Fe312 undergoes substitution reactions, making, for example, Fe311 upon reaction with triphenylphosphine. Heating Fe312 gives a low yield of the carbido cluster Fe515C, such reactions proceed via disproportionation of CO to give CO2 and carbon. Fe312 form ferroles upon reaction with heterocycles such as thiophenes, Fe312 reacts with thiols and disulfides to give thiolate-bridged complexes, such as methylthioirontricarbonyl dimer,2 Fe312 +3 2S2 →32 +6 CO. These complexes are studied as hydrogenase mimics, Fe312 is hazardous as a source of volatile iron and as a source of carbon monoxide. Solid samples, especially when finely divided, and residues from reactions can be pyrophoric, which can ignite the organic solvents used for such reactions
29.
(Benzylideneacetone)iron tricarbonyl
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The organometallic compound iron tricarbonyl is a reagent for transferring the Fe3 unit to other organic molecules. This red-colored compound is commonly abbreviated Fe3 and it is prepared by the reaction of Fe29 with benzylideneacetone, typically in refluxing diethyl ether. The compound is characterized by IR bands at 2065,2005, a popular source of Fe3 is Fe29. Alternatively, Fe32 is highly reactive, the trade-off being that it is thermally sensitive, imine derivatives of cinnamaldehyde, e. g. C6H5CH=CHC=NC6H5, form conveniently reactive Fe3 adducts, which have been shown to be superior in some ways to Fe3. Fe3 reacts with Lewis bases to give adducts without displacement of the bda
30.
Iron(I) hydride
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Iron hydride is a chemical compound of iron and hydrogen with chemical formula FeH. It has been detected in only in extreme environments, like trapped in frozen noble gases, in the atmosphere of cool stars. It is assumed to have three dangling valence bonds, and is therefore a free radical, its formula may be written FeH3• to emphasize this fact, at very low temperatures, FeH may form a complex with molecular hydrogen FeH·H2. Iron hydride was first detected in the laboratory by B, kleman and L. Åkerlind in the 1950s. Iron hydride is one of the few found in the Sun. Lines for FeH in the part of the solar spectrum were reported in 1972. Also sunspot umbras show up the Wing-Ford band prominently, bands for FeH show up prominently in the emission spectra for M dwarfs and L dwarfs, the hottest kind of brown dwarf. For cooler T dwarfs, the bands for FeH do not appear, probably due to liquid iron clouds blocking the view of the atmosphere, for even cooler brown dwarfs, signals for FeH reappear, which is explained by the clouds having gaps. The explanation for the kind of stars that the FeH Wing-Ford band appears in, is that the temperature is around 3000 K, once the temperature reaches 4000 K as in a K dwarf the line is weaker due to more of the molecules being dissociated. In M giant red giants the gas pressure is too low for FeH to form, elliptical and lenticular galaxies have also have an observable Wing-Ford band, due to a large amount of their light coming from M dwarfs. Kleman and Åkerlind first produced FeH in the laboratory by heating iron to 2600 K in a King-type furnace under a thin hydrogen atmosphere, molecular FeH can also be obtained by vaporizing iron in an argon-hydrogen atmosphere and freezing the gas on a solid surface at about 10 K. The compound can be detected by infrared spectroscopy, and about half of it disappears when the sample is briefly warmed to 30 K, a variant technique uses pure hydrogen atmosphere condensed at 4 K. This procedure also generates molecules that were thought to be FeH3 but were assigned to an association of FeH. Molecular FeH has been produced by the decay of 57Co embedded in solid hydrogen, mössbauer spectroscopy revealed an isomer shift of 0.59 mm/s compared with metallic iron and quadrupole splitting of 2.4 mm/s. FeH can also be produced by the interaction of Iron pentacarbonyl vapour, FeH is predicted to have a quartet and a sextet ground states. The FeH molecule has at least four low energy electronic states caused by the non bonding electron taking up positions in different orbitals, X4Δ, a6Δ b6Π, higher energy states are termed B4Σ−, C4Φ, D4Σ+, E4Π, and F4Δ. Even higher levels are labelled G4Π and H4Δ from the system, and d6Σ−, e6Π, f6Δ. In the quartet states the quantum number J takes on values 1/2, 3/2, 5/2
31.
Organoiron chemistry
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Organoiron chemistry is the chemistry of iron compounds containing a carbon-to-iron chemical bond. Organoiron compounds are relevant in organic synthesis as reagents such as iron pentacarbonyl, diiron nonacarbonyl, iron adopts oxidation states from Fe through to Fe. Although iron is less active in many catalytic applications, it is less expensive. The simple peralkyl and peraryl complexes of iron are far less developed than are the Cp, examples of compounds in this class are Fe4 and tetramesityldiiron. Important iron carbonyls are the three neutral binary carbonyls, iron pentacarbonyl, diiron nonacarbonyl, and triiron dodecacarbonyl, one or more carbonyl ligands in these compounds can be replaced by a variety of other ligands. Iron carbonyls have been used in stoichiometric carbonylation reactions, e. g. for the conversion of alkyl bromides to aldehydes, in a complementary reaction, Collmans reagent can be used to convert acyl chlorides to aldehydes. Similar reactions can be achieved with − salts, iron diene complexes are usually prepared from Fe5 or Fe29. Derivatives are known for common dienes are cyclohexadiene, norbornadiene and cyclooctadiene, in the complex with butadiene, the diene adopts a cis-conformation. Iron carbonyls are used as a group for dienes in hydrogenations. Cyclobutadieneiron tricarbonyl is prepared from 3, 4-dichlorocyclobutene and Fe29, cyclohexadienes, many derived from Birch reduction of aromatic compounds, form derivatives Fe3. The affinity of the Fe3 unit for conjugated dienes is manifested in the ability of iron carbonyls catalyse the isomerisations of 1, 5-cyclooctadiene to 1, cyclohexadiene complexes undergo hydride abstraction to give cyclohexadienyl cations, which add nucleophiles. The enone complex iron tricarbonyl serves as a source of the Fe3 subunit and is employed to prepare other derivatives and it is used complementarily to Fe29. Alkynes form many compounds with upon reaction with iron carbonyls and these include cyclobutadiene derivatives, ferroles of the formula Fe26, as well as cyclopentadienone and cyclobutadiene derivatives. Complexes of the type Fe226 and Fe226 form, usually by the reaction of thiols, the thiolates can also be obtained from the tetrahedrane Fe2S26. Ferrocene is also a structurally unusual scaffold as illustrated by the popularity of such as 1, 1-bisferrocene. Treatment of ferrocene with aluminium trichloride and benzene gives the cation +, oxidation of ferrocene gives the blue 17e species ferrocenium. Derivatives of fullerene can also act as a highly substituted cyclopentadienyl ligand, Fe5 reacts with dicyclopentadiene to give the cyclopentadienyliron dicarbonyl dimer. Reduction of this species with sodium gives NaFp, a potent nucleophile, fp can also be synthesized photochemically using UV-Visible light
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Cyclopentadienyliron dicarbonyl dimer
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Cyclopentadienyliron dicarbonyl dimer is an organometallic compound with the formula 2Fe24, also abbreviated Cp2Fe24. It is called Fp2 or fip dimer, Cp2Fe24 is insoluble in but stable toward water. In solution, Cp2Fe24 can be considered a dimeric half-sandwich complex and it exists in three isomeric forms, cis, trans, and unbridged. These isomeric forms are distinguished by the position of the ligands, cis and trans differ in the relative position of C5H5 ligands. For both the cis and trans isomers, two CO ligands are terminal whereas the other two CO ligands bridge between the iron atoms, however, in the unbridged isomer, no ligands bridge between iron atoms — the metals are held together only by the Fe–Fe bond. Cis and trans isomers are the more abundant, in solution, the three isomers interconvert. The phenomenon of rapidly interconverting structures is called fluxionality, the fluxional process for cyclopentadienyliron dicarbonyl dimer is so fast that only an averaged, single signal is observed in 1H NMR spectrum. However, the process is not fast enough to produce averaging in the IR spectrum. Thus, three absorptions are seen for each isomer, the νCO bands for bridging CO ligands are around 1780 cm−1 whereas νCO bands for terminal CO ligands are about 1980 cm−1. The solid-state molecular structure of both cis and trans isomers have been analyzed by X-ray and neutron diffraction, although older textbooks show the two iron atoms bonded to each other, theoretical analyses indicated the absence of a direct Fe–Fe bond. Cp2Fe24 was first prepared by the method employed today, the reaction of iron pentacarbonyl. The method is used in the teaching laboratory, although of no major commercial value, Fp is a workhorse in organometallic chemistry because it is inexpensive and rugged. Reductive cleavage of the Cp2Fe24 produces derivatives formally derived from the cyclopentadienyliron dicarbonyl anion, − or called Fp−, a typical reductant is sodium metal or sodium amalgam, NaK alloy, and alkali metal trialkylborohydrides have been used. CpFe2]Na is a widely studied reagent since it is readily alkylated, acylated, halogens oxidatively cleave Fp2 to give FpX,2 + X2 →2 CpFe2X One example is cyclopentadienyliron dicarbonyl iodide. In the presence of halide anion acceptors such as AlBr3, FpX compounds react with alkenes to afford cationic alkene–Fp complexes, in some cases, salts of + are precursors to other Fp–alkene complexes. The exchange process is facilitated by the loss of gaseous isobutene, alkene–Fp complexes can also be prepared from Fp anion indirectly. Thus, hydride abstraction from Fp–alkyl compounds using triphenylmethyl hexafluorophosphate affords + complexes, FpNa + RCH2CH2I → FpCH2CH2R + NaI FpCH2CH2R + Ph3CPF6 → PF−6 + Ph3CH Reaction of NaFp with an epoxide followed by acid-promoted dehydration also affords alkene complexes. Fp+ are stable with respect to bromination, hydrogenation, and acetoxymercuration, the alkene ligand in these cations is activated toward attack by nucleophiles, opening the way to a number of carbon–carbon bond-forming reactions
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Cementite
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Cementite, also known as iron carbide, is an intermetallic compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By weight, it is 6. 67% carbon and 93. 3% iron and it has an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, therefore, in carbon steels and cast irons that are slowly cooled, a portion of the carbon is in the form of cementite. Cementite forms directly from the melt in the case of white cast iron, in carbon steel, cementite precipitates from austenite as austenite transforms to ferrite on slow cooling, or from martensite during tempering. An intimate mixture with ferrite, the product of austenite. Cementite changes from ferromagnetic to paramagnetic at its Curie temperature of approximately 480 K, a natural iron carbide occurs in iron meteorites and is called cohenite after the German mineralogist Emil Cohen, who first described it. The figure shows the behaviour at room temperature. There are other forms of iron carbides that have been identified in tempered steel. These include Epsilon carbide, hexagonal close-packed Fe2-3C, precipitates in plain-carbon steels of carbon content >0. 2%, non-stoichiometric ε-carbide dissolves above ~200 °C, where Hägg carbides and cementite begin to form. Hägg carbide, monoclinic Fe5C2, precipitates in hardened tool steels tempered at 200-300 °C, characterization of different iron carbides is not at all a trivial task, and often X-ray diffraction is complemented by Mössbauer spectroscopy. Foundations of Materials Science and Engineering, microstructure of Steels and Cast Irons. Ester Esna du Plessis The Crystal Structures of Iron Carbides, Ph. D, formation of Fe7C3 and Fe5C2 type metastable carbides during the crystallization of an amorphous Fe75C25 alloy
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Iron(II) bromide
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Iron bromide is the chemical compound with the chemical formula FeBr2. The anhydrous compound is a yellow or brownish-colored paramagnetic solid and it is a common precursor to other iron compounds in research laboratory. Several hydrates of FeBr2 are also known, like most metal halides, FeBr2 adopts a polymeric structure consisting of isolated metal centers cross-linked with halides. It crystallizes with the CdI2 structure, featuring close-packed layers of bromide ions, the packing of the halides is slightly different from that for FeCl2, which adopts the CdCl2 motif. FeBr2 is synthesized using a solution of concentrated hydrobromic acid. Gives the methanol solvate Br2 together with hydrogen gas, heating the methanol complex in a vacuum gives pure FeBr2. Iron bromide cannot be formed by the reaction of iron and bromine, FeBr2 reacts with 2 equivalents of 4NBr to give 2FeBr4. FeBr2 reacts with bromide and bromine to form the intensely colored, FeBr2 is a weak reducing agent, as are all ferrous compounds
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Iron(II) chloride
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Iron chloride, also known as ferrous chloride, is the chemical compound of formula FeCl2. It is a solid with a high melting point. The compound is white, but typical samples are often off-white, FeCl2 crystallizes from water as the greenish tetrahydrate, which is the form that is most commonly encountered in commerce and the laboratory. The compound is soluble in water, aqueous solutions of FeCl2 are highly transparent. Hydrated forms of ferrous chloride are generated by treatment of wastes from steel production with hydrochloric acid, such solutions are designated spent acid, especially when the hydrochloric acid is not completely consumed, Fe +2 HCl → FeCl2 + H2 The spent acid requires treatment before its disposal. It is also byproduct from titanium production, since some titanium ores contain iron, the dihydrate crystallizes from concentrated hydrochloric acid. Ferrous chloride is prepared by addition of iron powder to a solution of methanol. This reaction gives the methanol solvate, which upon heating in a vacuum at about 160 °C gives anhydrous FeCl2, feBr2 and FeI2 can be prepared analogously. Fe +2 HCl → FeCl2 + H2 An alternative synthesis of entails the reduction of FeCl3 with chlorobenzene,2 FeCl3 + C6H5Cl →2 FeCl2 + C6H4Cl2 + HCl FeCl2 is soluble in tetrahydrofuran. In one of two classic syntheses of ferrocene, Wilkinson generated FeCl2 by heating FeCl3 with iron powder in THF, ferric chloride decomposes to ferrous chloride at high temperatures. The dihydrate, FeCl22, is a coordination polymer, each Fe center is coordinated to four doubly bridging chloride ligands. The octahedron is completed by a pair of mutually trans aquo ligands, FeCl2 and its hydrates form complexes with many ligands. The anhydrous FeCl2 is a precursor in organometallic synthesis. Solutions of the hydrates react with two equivalents of Cl to give the salt 2. Ferrous chloride has a variety of applications, but the related compounds ferrous sulfate. Aside from use in the synthesis of iron complexes, ferrous chloride serves as a reducing flocculating agent in wastewater treatment. It is the precursor to hydrated iron oxides that are magnetic pigments, ferrous chloride is employed as a reducing agent in many organic synthesis reactions
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Iron(II) fluoride
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Iron fluoride or ferrous fluoride is an inorganic compound with the molecular formula FeF2. It forms a tetrahydrate FeF2·4H2O that is referred to by the same names. The anhydrous and hydrated forms are white crystalline solids, anhydrous FeF2 adopts the TiO2 rutile structure. As such, the cations are octahedral and fluoride anions are trigonal planar. The tetrahydrate can exist in two structures, or polymorphs, one form is rhombohedral and the other is hexagonal, the former having a disorder. Like most fluoride compounds, the anhydrous and hydrated forms of iron fluoride feature high spin metal center, low temperature neutron diffraction studies show that the FeF2 is antiferromagnetic. Heat capacity measurements reveal an event at 78.3 K corresponding to ordering of antiferromagnetic state, FeF2 sublimes between 958 and 1178 K. Using Torsion and Knudsen methods, the heat of sublimation was experimentally determined and averaged to be 271 ±2 kJ mole−1 and it is slightly soluble in water as well as dilute hydrofluoric acid, giving a pale green solution. It is insoluble in organic solvents, the tetrahydrate can be prepared by dissolving iron in warm hydrated hydrofluoric acid and precipitating the result by addition of ethanol. It oxidizes in moist air to give, inter alia, a hydrate of iron fluoride, FeF2 is used to catalyze some organic reactions. National Pollutant Inventory - Fluoride and compounds fact sheet
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Iron(II) oxide
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Iron oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite, one of several iron oxides, it is a black-colored powder that is sometimes confused with rust, which consists of hydrated iron oxide. Iron oxide also refers to a family of related non-stoichiometric compounds, FeO can be prepared by the thermal decomposition of iron oxalate. FeC2O4 → FeO + CO2 + CO The procedure is conducted under an atmosphere to avoid the formation of ferric oxide. A similar procedure can also be used for the synthesis of manganous oxide, stoichiometric FeO can be prepared by heating Fe0. 95O with metallic iron at 770 °C and 36 kbar. Below 200 K there is a change to the structure which changes the symmetry to rhombohedral. Iron oxide makes up approximately 9% of the Earths mantle, within the mantle, it may be electrically conductive, which is a possible explanation for perturbations in Earths rotation not accounted for by accepted models of the mantles properties. Iron oxide is used as a pigment and it is FDA-approved for use in cosmetics and it is used in some tattoo inks. It can also be used as a phosphate remover from home aquaria
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Iron(II) hydroxide
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Iron hydroxide or ferrous hydroxide is a inorganic compound with the formula Fe2. It is produced when iron salts, from a compound such as sulfate, are treated with hydroxide ions. Iron hydroxide is a solid, but even traces of oxygen impart a greenish tinge. The air-oxidized solid is known as green rust. Iron hydroxide is poorly soluble, or 10−14 mol/L, iron ions are easily substituted by iron ions produced by its progressive oxidation. It is also formed as an by-product of other reactions, a. o. in the synthesis of siderite. Fe2 is a layer double hydroxide, the mineralogical form of green rust is a recently discovered. All forms of green rust are more complex and variable than the iron hydroxide compound. The natural analogue of iron compound is a very rare mineral amakinite,2. Under anaerobic conditions, the hydroxide can be oxidized by the protons of water to form magnetite. The resulting products are poorly soluble, iron hydroxide has also been investigated as an agent for the removal of toxic selenate and selenite ions from water systems such as wetlands. The iron hydroxide reduces these ions to elemental selenium, which is insoluble in water, in a basic solution iron hydroxide is the electrochemically active material of the negative electrode of the nickel-iron battery
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Iron(II) sulfide
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Iron sulfide or ferrous sulfide is a chemical compound with the formula FeS. In practice, iron sulfides are often iron-deficient non-stoichiometric, some of the hydrogen sulfide will react with metal ions in the water to produce metal sulfides, which are not water-soluble. These metal sulfides, such as sulfide, are often black or brown. Pyrrhotite is a product of the Desulfovibrio bacteria, a sulfate reducing bacteria. When eggs are cooked for a time, the yolks surface may turn green. This is due to iron sulfide which forms as iron from the yolk meets hydrogen sulfide released from the egg white by the heat and this reaction occurs more rapidly in older eggs as the whites are more alkaline. Peptone iron agar contains the amino acid cysteine and a chemical indicator, the degradation of cysteine releases hydrogen sulfide gas that reacts with the ferric citrate to produce ferrous sulfide. Iron sulfide Troilite Pyrite Iron-sulfur world theory
