Ammonium chloride is an inorganic compound with the formula NH4Cl and a white crystalline salt, soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of the mineralogical form of ammonium chloride; the mineral is formed on burning coal dumps from condensation of coal-derived gases. It is found around some types of volcanic vents, it is used as fertilizer and a flavouring agent in some types of liquorice. It is the product from the reaction of hydrochloric ammonia, it is a product of the Solvay process used to produce sodium carbonate: CO2 + 2 NH3 + 2 NaCl + H2O → 2 NH4Cl + Na2CO3In addition to being the principal method for the manufacture of ammonium chloride, that method is used to minimize ammonia release in some industrial operations. Ammonium chloride is prepared commercially by combining ammonia with either hydrogen chloride or hydrochloric acid: NH3 + HCl → NH4ClAmmonium chloride occurs in volcanic regions, forming on volcanic rocks near fume-releasing vents.
The crystals deposit directly from the gaseous state and tend to be short-lived, as they dissolve in water. Ammonium chloride appears to sublime upon heating but decomposes into ammonia and hydrogen chloride gas. NH4Cl → NH3 + HClAmmonium chloride reacts with a strong base, like sodium hydroxide, to release ammonia gas: NH4Cl + NaOH → NH3 + NaCl + H2OSimilarly, ammonium chloride reacts with alkali metal carbonates at elevated temperatures, giving ammonia and alkali metal chloride: 2 NH4Cl + Na2CO3 → 2 NaCl + CO2 + H2O + 2 NH3A 5% by weight solution of ammonium chloride in water has a pH in the range 4.6 to 6.0. Some of ammonium chloride's reactions with other chemicals are endothermic like its reaction with barium hydroxide and its dissolving in water; the dominant application of ammonium chloride is as a nitrogen source in fertilizers such as chloroammonium phosphate. The main crops fertilized this way are wheat in Asia. Ammonium chloride was used in pyrotechnics in the 18th century but was superseded by safer and less hygroscopic chemicals.
Its purpose was to provide a chlorine donor to enhance the green and blue colours from copper ions in the flame. It had a secondary use to provide white smoke, but its ready double decomposition reaction with potassium chlorate producing the unstable ammonium chlorate made its use suspect. Ammonium chloride galvanized or soldered, it works as a flux by cleaning the surface of workpieces by reacting with the metal oxides at the surface to form a volatile metal chloride. For that purpose, it is sold in blocks at hardware stores for use in cleaning the tip of a soldering iron, it can be included in solder as flux. Ammonium chloride is used as an expectorant in cough medicine, its expectorant action is caused by irritative action on the bronchial mucosa, which causes the production of excess respiratory tract fluid, easier to cough up. Ammonium salts may induce nausea and vomiting. Ammonium chloride is used as a systemic acidifying agent in treatment of severe metabolic alkalosis, in oral acid loading test to diagnose distal renal tubular acidosis, to maintain the urine at an acid pH in the treatment of some urinary-tract disorders.
Ammonium chloride, under the name sal ammoniac or salmiak is used as food additive under the E number E510, working as a yeast nutrient in breadmaking and as an acidifier. It is a feed supplement for cattle and an ingredient in nutritive media for yeasts and many microorganisms. Ammonium chloride is used to spice up dark sweets called salmiak, in baking to give cookies a crisp texture, in the liquor Salmiakki Koskenkorva for flavouring. In Iran, India and Arab countries it is called "Noshader" and is used to improve the crispness of snacks such as samosas and jalebi. Ammonium chloride has been used to produce low temperatures in cooling baths. Ammonium chloride solutions with ammonia are used as buffer solutions including ACK lysis buffer. In paleontology, ammonium chloride vapor is deposited on fossils, where the substance forms a brilliant white removed and harmless and inert layer of tiny crystals; that covers up any coloration the fossil may have, if lighted at an angle enhances contrast in photographic documentation of three-dimensional specimens.
The same technique is applied in archaeology to eliminate reflection on glass and similar specimens for photography. In organic synthesis saturated NH4Cl solution is used to quench reaction mixtures. Giant squid and some other large squid species maintain neutral buoyancy in seawater through an ammonium chloride solution, found throughout their bodies and is less dense than seawater; this differs from the method of flotation used by most fish, which involves a gas-filled swim bladder. The solution tastes somewhat like salmiakki and makes giant squid unattractive for general human consumption. Ammonium chloride is used in a ~5% aqueous solution to work on oil wells with clay swelling problems, it is used as electrolyte in zinc–carbon batteries. Other uses include in hair shampoo, in the glue that bonds plywood, in cleaning products. In hair shampoo, it is used as a thickening agent in ammonium-based surfactant systems such as ammonium lauryl sulfate. Ammonium chloride is used in the textile and leather industry, in dyeing, textile printing and cotton clustering.
Around the turn of the 20th Century, Ammonium Chloride was used in aqueous solution as the electrolyte in
Royal Society of Chemistry
The Royal Society of Chemistry is a learned society in the United Kingdom with the goal of "advancing the chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Royal Institute of Chemistry, the Faraday Society, the Society for Analytical Chemistry with a new Royal Charter and the dual role of learned society and professional body. At its inception, the Society had a combined membership of 34,000 in the UK and a further 8,000 abroad; the headquarters of the Society are at Burlington House, London. It has offices in Thomas Graham House in Cambridge where RSC Publishing is based; the Society has offices in the United States at the University City Science Center, Philadelphia, in both Beijing and Shanghai and Bangalore, India. The organisation carries out research, publishes journals and databases, as well as hosting conferences and workshops, it is the professional body for chemistry in the UK, with the ability to award the status of Chartered Chemist and, through the Science Council the awards of Chartered Scientist, Registered Scientist and Registered Science Technician to suitably qualified candidates.
The designation FRSC is given to a group of elected Fellows of the society who have made major contributions to chemistry and other interface disciplines such as biological chemistry. The names of Fellows are published each year in The Times. Honorary Fellowship of the Society is awarded for distinguished service in the field of chemistry; the president is elected biennially and wears a badge in the form of a spoked wheel, with the standing figure of Joseph Priestley depicted in enamel in red and blue, on a hexagonal medallion in the centre. The rim of the wheel is gold, the twelve spokes are of non-tarnishable metals; the current president is Dame Carol V. Robinson. Past presidents of the society have been: The following are membership grades with post-nominals: Affiliate: The grade for students and those involved in chemistry who do not meet the requirements for the following grades. AMRSC: Associate Member, Royal Society of Chemistry The entry level for RSC membership, AMRSC is awarded to graduates in the chemical sciences.
MRSC: Member, Royal Society of Chemistry Awarded to graduates with at least 3 years' experience, who have acquired key skills through professional activity FRSC: Fellow of the Royal Society of Chemistry Fellowship may be awarded to nominees who have made an outstanding contribution to chemistry. HonFRSC: Honorary Fellow of the Society Honorary Fellowship is awarded for distinguished service in the field of chemistry. CChem: Chartered Chemist The award of CChem is considered separately from admission to a category of RSC membership. Candidates need to be MRSC or FRSC and demonstrate development of specific professional attributes and be in a job which requires their chemical knowledge and skills. CSci: Chartered Scientist The RSC is a licensed by the Science Council for the registration of Chartered Scientists. EurChem: European Chemist The RSC is a member of the European Communities Chemistry Council, can award this designation to Chartered Chemists. MChemA: Mastership in Chemical Analysis The RSC awards this postgraduate qualification, the UK statutory qualification for practice as a Public Analyst.
It requires candidates to submit a portfolio of suitable experience and to take theory papers and a one-day laboratory practical examination. The qualification GRSC was awarded from 1981 to 1995 for completion of college courses equivalent to an honours chemistry degree and overseen by the RSC, it replaced the GRIC offered by the Royal Institute of Chemistry. The society is organised around 9 divisions, based on subject areas, local sections, both in the United Kingdom and overseas. Divisions cover broad areas of chemistry but contain many special interest groups for more specific areas. Analytical Division for analytical chemistry and promoting the original aims of the Society for Analytical Chemistry. 12 Subject Groups. Dalton Division, named after John Dalton, for inorganic chemistry. 6 Subject Groups. Education Division for chemical education. 4 Subject Groups. Faraday Division, named after Michael Faraday, for physical chemistry and promoting the original aims of the Faraday Society. 14 Subject Groups.
Organic Division for organic chemistry. 6 Subject Groups. Chemical Biology Interface Division. 2 Subject Groups. Environment and Energy Division. 3 Subject Groups. Materials Chemistry Division. 4 Subject Groups. Industry and Technology Division. 13 Subject Groups. There are 12 subjects groups not attached to a division. There are 35 local sections covering the United Ireland. In countries of the Commonwealth of Nations and many other countries there are Local Representatives of the society and some activities; the society is a not-for-profit publisher: surplus made by its publishing business is invested to support its aim of advancing the chemical sciences. In addition to scientific journals, including its flagship journals Chemical Communications, Chemical Science and Chemical Society Reviews, the society publishes: Education in Chemistry for teachers. A free online journal for chemistry educators, Chemistry Education Research and Practice. A general chemistry magazine Chemistry World, sent monthly to all members of the Society throughout the world.
The editorial board consists of 10 industrial chemists. It was first published in January 2004, it replaced C
The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium; the melting point of a substance depends on pressure and is specified at a standard pressure such as 1 atmosphere or 100 kPa. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point; because of the ability of some substances to supercool, the freezing point is not considered as a characteristic property of a substance. When the "characteristic freezing point" of a substance is determined, in fact the actual methodology is always "the principle of observing the disappearance rather than the formation of ice", that is, the melting point. For most substances and freezing points are 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. 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 not always the same as the melting point. In the absence of nucleators water can exist as a supercooled liquid down to −48.3 °C before freezing. The chemical element with the highest melting point is tungsten, at 3,414 °C; the often-cited carbon does not melt at ambient pressure but sublimes at about 3,726.85 °C. Tantalum hafnium carbide is a refractory compound with a high melting point of 4215 K. At the other end of the scale, helium does not freeze at all at normal pressure at temperatures arbitrarily close to absolute zero. 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 and a simple magnifier. The several grains of a solid are placed in a thin glass tube and immersed in the oil bath; the oil bath is heated and with the aid of the magnifier melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, optical detection is automated; the measurement can be made continuously with an operating process. For instance, oil refineries measure the freeze point of diesel fuel online, meaning that the sample is taken from the process and measured automatically; this allows for more frequent measurements as the sample does not have to be manually collected and taken to a remote laboratory. For refractory materials the 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, 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; this extrapolation is accomplished by using Planck's law of radiation. The constants in this equation are not known with sufficient accuracy, causing errors in the extrapolation to become larger at higher temperatures. However, standard techniques have been developed to perform this extrapolation. Consider the case of using gold as the source. In this technique, the current through the filament of the pyrometer is adjusted until the light intensity of the filament matches that of a black-body at the melting point of gold.
This establishes the primary calibration temperature and can be expressed in terms of current through the pyrometer lamp. With the same current setting, the pyrometer is sighted on another black-body at a higher temperature. An absorbing medium of known transmission is inserted between this black-body; the temperature of the black-body is adjusted until a match exists between its intensity and that of the pyrometer filament. The true higher temperature of the black-body is determined from Planck's Law; the absorbing medium is removed and the current through the filament is adjusted to match the filament intensity to that of the black-body. This establishes a second calibration point for the pyrometer; this step is repeated to carry the calibration to hi
A nitrile is any organic compound that has a −C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons. Inorganic compounds containing the − C ≡ N group cyanides instead. Though both nitriles and cyanides can be derived from cyanide salts, most nitriles are not nearly as toxic; the N−C−C geometry is linear in nitriles, reflecting the sp hybridization of the triply bonded carbon. The C−N distance is short at 1.16 Å, consistent with a triple bond. Nitriles are polar; as liquids, they have high relative permittivities in the 30s. The first compound of the homolog row of nitriles, the nitrile of formic acid, hydrogen cyanide was first synthesized by C. W. Scheele in 1782.
In 1811 J. L. Gay-Lussac was able to prepare the toxic and volatile pure acid. Around 1832 benzonitrile, the nitrile of benzoic acid, was prepared by Friedrich Wöhler and Justus von Liebig, but due to minimal yield of the synthesis neither physical nor chemical properties were determined nor a structure suggested. In 1834 Théophile-Jules Pelouze synthesized propionitrile, suggesting it to be an ether of propionic alcohol and hydrocyanic acid; the synthesis of benzonitrile by Hermann Fehling in 1844 by heating ammonium benzoate was the first method yielding enough of the substance for chemical research. Fehling determined the structure by comparing his results to the known synthesis of hydrogen cyanide by heating ammonium formate, he coined the name "nitrile" for the newfound substance, which became the name for this group of compounds. Industrially, the main methods for producing nitriles are hydrocyanation. Both routes are green in the sense. In ammoxidation, a hydrocarbon is oxidized in the presence of ammonia.
This conversion is practiced on a large scale for acrylonitrile: CH3CH=CH2 + 3⁄2 O2 + NH3 → NCCH=CH2 + 3 H2OIn the production of acrylonitrile, a side product is acetonitrile. On an industrial scale, several derivatives of benzonitrile, phthalonitrile, as well as Isobutyronitrile are prepared by ammoxidation; the process is assumed to proceed via the imine. Hydrocyanation is an industrial method for producing nitriles from hydrogen cyanide and alkenes; the process requires homogeneous catalysts. An example of hydrocyanation is the production of adiponitrile, a precursor to nylon-6,6 from 1,3-butadiene: CH2=CH−CH=CH2 + 2 HCN → NC4CN Two salt metathesis reactions are popular for laboratory scale reactions. In the Kolbe nitrile synthesis, alkyl halides undergo nucleophilic aliphatic substitution with alkali metal cyanides. Aryl nitriles are prepared in the Rosenmund-von Braun synthesis; the cyanohydrins are a special class of nitriles. Classically they result from the addition of alkali metal cyanides to aldehydes in the cyanohydrin reaction.
Because of the polarity of the organic carbonyl, this reaction requires no catalyst, unlike the hydrocyanation of alkenes. O-Silyl cyanohydrins are generated by the addition trimethylsilyl cyanide in the presence of a catalyst. Cyanohydrins are prepared by transcyanohydrin reactions starting, for example, with acetone cyanohydrin as a source of HCN. Nitriles can be prepared by the dehydration of primary amides. In the presence of ethyl dichlorophosphate and DBU benzamide converts to benzonitrile: Other reagents that are common used for this purpose include P4O10, SOCl2. Two intermediates in this reaction are amide tautomer A and its phosphate adduct B. In a related dehydration, secondary amides give nitriles by the von Braun amide degradation. In this case, one C-N bond is cleaved; the dehydration of aldoximes affords nitriles. Typical reagents for this transformation are triethylamine/sulfur dioxide, zeolites, or sulfuryl chloride. Exploiting this approach is the One-pot synthesis of nitriles from aldehyde with hydroxylamine in the presence of sodium sulfate.
From aryl carboxylic acids Aromatic nitriles are prepared in the laboratory from the aniline via diazonium compounds. This is the Sandmeyer reaction, it requires transition metal cyanides. ArN+2 + CuCN → ArCN + N2 + Cu+ A commercial source for the cyanide group is diethylaluminum cyanide Et2AlCN which can be prepared from triethylaluminium and HCN, it has been used in nucleophilic addition to ketones. For an example of its use see: Kuwajima Taxol total synthesis cyanide ions facilitate the coupling of dibromides. Reaction of α,α′-dibromoadipic acid with sodium cyanide in ethanol yields the cyano cyclobutane: In the so-called Franchimont Reaction an α-bromocarboxylic acid is dimerized after hydrolysis of the cyanogroup and decarboxylationAromatic nitriles can be prepared from base hydrolysis of trichloromethyl aryl ketimines in the Houben-Fischer synthesis Nitriles can be obtained from primary amines via oxidation. Common methods include the use of potassium persulfate, Trichloroisocyanuric acid, or anodic electrosynthesis.
Α-Amino acids form nitriles and carbon dioxide via various means of oxidative decarboxylation. Henry Drysdale Dakin discovered this oxidation in 1916. Nitrile groups in organic compounds can undergo a variety of reactions depending on the reactants or conditio
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring. Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis and applications of these heterocycles. Examples of heterocyclic compounds include all of the nucleic acids, the majority of drugs, most biomass, many natural and synthetic dyes. Although heterocyclic chemical compounds may be inorganic compounds or organic compounds, most contain at least one carbon. While atoms that are neither carbon nor hydrogen are referred to in organic chemistry as heteroatoms, this is in comparison to the all-carbon backbone, but this does not prevent a compound such as borazine from being labelled "heterocyclic". IUPAC recommends the Hantzsch-Widman nomenclature for naming heterocyclic compounds. Heterocyclic compounds can be usefully classified based on their electronic structure; the saturated heterocycles behave like the acyclic derivatives. Thus and tetrahydrofuran are conventional amines and ethers, with modified steric profiles.
Therefore, the study of heterocyclic chemistry focuses on unsaturated derivatives, the preponderance of work and applications involves unstrained 5- and 6-membered rings. Included are pyridine, thiophene and furan. Another large class of heterocycles are fused to benzene rings, which for pyridine, thiophene and furan are quinoline, benzothiophene and benzofuran, respectively. Fusion of two benzene rings gives rise to a third large family of compounds the acridine, dibenzothiophene and dibenzofuran; the unsaturated rings can be classified according to the participation of the heteroatom in the conjugated system, pi system. Heterocycles with three atoms in the ring are more reactive because of ring strain; those containing one heteroatom are, in general, stable. Those with two heteroatoms are more to occur as reactive intermediates. Common 3-membered heterocycles with one heteroatom are: Those with two heteroatoms include: Compounds with one heteroatom: Compounds with two heteroatoms: With heterocycles containing five atoms, the unsaturated compounds are more stable because of aromaticity.
The 5-membered ring compounds containing two heteroatoms, at least one of, nitrogen, are collectively called the azoles. Thiazoles and isothiazoles contain a nitrogen atom in the ring. Dithiolanes have two sulfur atoms. A large group of 5-membered ring compounds with three heteroatoms exists. One example is dithiazoles that contain a nitrogen atom. Six-membered rings with a single heteroatom: With two heteroatoms: With three heteroatoms: With four heteroatoms: With five heteroatoms: The hypothetical compound with six nitrogen heteroatoms would be hexazine. With 7-membered rings, the heteroatom must be able to provide an empty pi orbital for "normal" aromatic stabilization to be available. Compounds with one heteroatom include: Those with two heteroatoms include: Names in italics are retained by IUPAC and they do not follow the Hantzsch-Widman nomenclature Heterocyclic rings systems that are formally derived by fusion with other rings, either carbocyclic or heterocyclic, have a variety of common and systematic names.
For example, with the benzo-fused unsaturated nitrogen heterocycles, pyrrole provides indole or isoindole depending on the orientation. The pyridine analog is isoquinoline. For azepine, benzazepine is the preferred name; the compounds with two benzene rings fused to the central heterocycle are carbazole and dibenzoazepine. Thienothiophene are the fusion of two thiophene rings. Phosphaphenalenes are a tricyclic phosphorus-containing heterocyclic system derived from the carbocycle phenalene; the history of heterocyclic chemistry began in the 1800s, in step with the development of organic chemistry. Some noteworthy developments: 1818: Brugnatelli isolates alloxan from uric acid 1832: Dobereiner produces furfural by treating starch with sulfuric acid 1834: Runge obtains pyrrole by dry distillation of bones 1906: Friedlander synthesizes indigo dye, allowing synthetic chemistry to displace a large agricultural industry 1936: Treibs isolates chlorophyl derivatives from crude oil, explaining the biological origin of petroleum.
1951: Chargaff's rules are described, highlighting the role of heterocyclic compounds in the genetic code. Heterocyclic compounds are pervasive in many areas of technology. Many drugs are heterocyclic compounds. Hantzsch-Widman nomenclature, IUPAC Heterocyclic amines in cooked meat, US CDC List of known and probable carcinogens, American Cancer Society List of known carcinogens by the State of California, Proposition 65
In a reactive dye, a chromophore contains a substituent that reacts with the substrate. Reactive dyes have good fastness properties owing to the bonding. Reactive dyes are most used in dyeing of cellulose like cotton or flax, but wool is dyeable with reactive dyes. Reactive dyeing is the most important method for the coloration of cellulosic fibres. Reactive dyes can be applied on wool and nylon. Reactive dyes have a low utilization degree compared to other types of dyestuff, since the functional group bonds to water, creating hydrolysis. Reactive dyes had been tested in the late 1800s involving both adding functionalized dyes to the substrate and activating the substrate first followed by fixation of the dye; the first commercial success was described in the early 1950s. Rattee and Stephens at Imperial Chemical Industries popularlized the chlorotriazines as linkers between the substrate and the chromophore. Trichlorotriazines remain a popular platform for reactive dyes; the chromophore, with an amine functional group, is attached to the triazine, displacing one chloride: 3 + dye-NH2 → N3C3Cl2 + HClThe resulting dichlorotriazine can be affixed to the cellulose fibre by displacement of one of the two chloride groups: N3C3Cl2 + HO-cellulose → N3C3Cl + HClThe fixation process is conducted in a buffered alkaline dye bath.
An alternative fixation process, more dominant commercially is the vinylsulfonyl group. Like the chlorotriazines, this functional group adds to the hydroxyl groups of cellulose; the most popular version of this technology is Remazol. The dye is first attached to the ethylsulfonyl group. Reactive dyes are categorized by functional group. Dyestuffs with only one functional group sometimes have a low degree of fixation. To overcome this deficiency, dyestuffs containing two different reactive groups were developed; these dyestuffs containing two groups are known as bifunctional dyestuffs although some still refer to the original combination. Some contain two monochlorotriazines, others have a combination of the triazines and one vinyl sulfone group). Bifunctional dyes can be more tolerant to temperature deviations. Other bifunctionals have been created, only fixation degree in mind. Carbene dyes For more info Fundamental Chemistry of reactive dyes Advancements in Reactive Textile Dyes
Amidines are a class of oxoacid derivatives. The oxoacid from which an amidine is derived must be of the form RnEOH; the −OH group is replaced by an −NH2 group and the =O group is replaced by =NR, giving amidines the general structure RnENR2. When the parent oxoacid is a carboxylic acid, the resulting amidine is a carboxamidine or carboximidamide, has the following general structure: Carboxamidines are referred to as amidines, as they are the most encountered type of amidine in organic chemistry; the simplest amidine is formamidine, HCNH2. Examples of amidines include: DBU diminazene benzamidine Pentamidine ParanylineThe most common way to make primary amidines is by the Pinner reaction. Reaction of the nitrile with acidic alcohol gives an iminoether. Amidines are among the strongest uncharged/unionized bases. Protonation occurs onto the sp² hybridized nitrogen; this occurs. The resulting cationic species possesses identical C-N bond lengths. A notable subclass of amidinium ions are the formamidinium cations.
Deprotonation of these gives stable carbenes which can be represented by the chemical formula R2N−C:−NR2. An amidinate salt has the general structure M+− and can be accessed by reaction of a carbodiimide with an organometallic compound such as methyl lithium, they are used as ligands in organometallic complexes. Guanidines — a similar group of compounds where the central Carbon is bonded to three Nitrogens. Imidazolines contain a cyclic amidine