Vanadium oxide is the inorganic compound with the formula V2O3. It is a black solid prepared by reduction of V2O5 with hydrogen or carbon monoxide. It is a basic oxide dissolving in acids to give solutions of vanadium complexes and it is antiferromagnetic with a critical temperature of 160 K. At this temperature there is a change in conductivity from metallic to insulating. Upon exposure to air it gradually converts into indigo-blue V2O4, in nature it occurs as the rare mineral karelianite
European Chemicals Agency
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 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 gives European consumers the right to ask whether the goods they buy contain dangerous substances. The Classification 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 move to another list
Vanadium tetrachloride is the inorganic compound with the formula VCl4. This bright red liquid is a reagent for the preparation of other vanadium compounds. With one more electron than diamagnetic TiCl4, VCl4 is a paramagnetic liquid. It is one of only a few compounds that is liquid at room temperature. VCl4 is prepared by chlorination of vanadium metal, vCl5 does not form in this reaction, Cl2 lacks the oxidizing power to attack VCl4. VCl5 can be prepared indirectly, by metathesis of VF5 with BCl3 at −78 °C, in contrast, the heavier analogues NbCl5 and TaCl5 are stable and not particularly oxidizing. VF5 can be prepared directly by fluorination of vanadium metal, reflecting the increased oxidizing power of F2 vs Cl2, indicative of its oxidizing power, VCl4 releases Cl2 at its boiling point to afford VCl3. Consistent with its high oxidizing power, VCl4 reacts with HBr at -50 °C to produce VBr3, the reaction proceeds via VBr4, which releases Br2 during warming to room temperature. 2 VCl4 +8 HBr →2 VBr3 +8 HCl + Br2 VCl4 forms adducts with many ligands, for example.
It is the precursor to vanadocene dichloride, VCl4 is a catalyst for the polymerization of alkenes, especially those useful in the rubber industry. The underlying technology is related to Ziegler–Natta catalysis, which involves the intermediacy of vanadium alkyls, in organic synthesis, VCl4 is used to couple phenols. For example, it converts phenol into 4, 4′-biphenol and it is reduced to VCl 3 in the process. 2 C6H5OH +2 VCl4 → HOC6H4–C6H4OH +2 VCl3 +2 HCl This reaction highlights the ability of VCl4. VCl4 is a volatile, aggressive oxidant that readily hydrolyzes to release HCl
Vanadium hexacarbonyl is the inorganic compound with the formula V6. It is a volatile solid. This highly reactive species is noteworthy from theoretical perspectives as a rare isolable homoleptic metal carbonyl that is paramagnetic, most species with the formula Mxy follow the 18-electron rule, whereas V6 has 17 valence electrons. Traditionally V6 is prepared in two-steps via the intermediacy of V−6, in the first step, VCl3 is reduced with metallic sodium under 200 atm CO at 160 °C. The solvent for this reduction is typically diglyme, CH3OCH2CH2OCH2CH2OCH3 and its primary reaction is reduction to the monoanion V−6, salts of which are well studied. It is susceptible to substitution by tertiary phosphine ligands, often leading to disproportionation, V6 reacts with sources of the cyclopentadienyl anion to give the orange four-legged piano stool complex V4. Like many charge-neutral organometallic compounds, this species is volatile. In the original preparation of this species, C5H5HgCl was employed as the source of C 5H−5, V6 adopts an octahedral coordination geometry and is isostructural with chromium hexacarbonyl, even though they have differing valence electron counts.
High resolution X-ray crystallography indicates that the molecule is distorted with two shorter V–C distances of 1.993 Å vs. four 2.005 Å. Even though V is a larger ion than V, the V–C distances in V−6 are 0.07 Å shorter than in the neutral precursor, original synthesis, Calderazzo, F. Ercoli, R. Synthesis of V6 and Hexacarbonyl Vanadates
Vanadium fluoride is an inorganic compound of vanadium and fluorine. It is paramagnetic yellow-brown solid that is very hygroscopic, unlike the corresponding vanadium tetrachloride, the tetrafluoride is not volatile because it adopts a polymeric structure. VF4 can be prepared by treating VCl4 with HF, VCl4 +4 HF → VF4 +4 HCl It was first prepared in this way. It decomposes at 325 °C, undergoing disproportionation to the tri-, each vanadium centre is octahedral, surrounded by six fluoride ligands. Four of the fluoride centers bridge to adjacent vanadium centres, webElements Cotton, F. Albert, Geoffrey, Carlos A. Bochmann, Advanced Inorganic Chemistry, New York, Wiley-Interscience, ISBN 0-471-19957-5
Vanadyl acetylacetonate is the chemical compound with the formula VO2, where acac– is the conjugate base of acetylacetone. It is a solid that dissolves in polar organic solvents. The coordination complex consists of the group, VO2+, bound to two acac– ligands via the two oxygen atoms on each. Like other charge-neutral acetylacetonate complexes, it is not soluble in water, the complex is generally prepared from vanadium, e. g. vanadyl sulfate, VOSO4 +2 Hacac → VO2 + H2SO4 It can be prepared by a redox reaction starting with vanadium pentoxide. In this reaction, some acetylacetone is oxidized to acetic anhydride, the complex has a square pyramidal structure with a short V=O bond. Its optical spectrum exhibits two transitions and it is a weak Lewis acid, forming adducts with pyridine and methylamine. It is used in chemistry as a catalyst for the epoxidation of allylic alcohols by tert-butyl hydroperoxide. The VO2–TBHP system exclusively epoxidizes geraniol at the allylic alcohol position, by comparison, m-CPBA, another epoxidizing agent, reacts with both alkenes, creating the products in a two to one ratio favoring reaction at the alkene away from the hydroxyl group. TBHP oxidizes VO2 to a species which coordinates the alcohol of the substrate.
Vanadyl exhibits insulin mimetic properties, in that in can stimulate the phosphorylation of protein kinase B and glycogen synthase kinase 3
International Standard Book Number
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, 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 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
Vanadium dioxide is an inorganic compound with the formula VO2. Vanadium dioxide is amphoteric, dissolving in non-oxidising acids to give the blue vanadyl ion, 2+ and in alkali to give the brown 2− ion, VO2 has a phase transition very close to room temperature. Electrical resistivity, etc, can change up several orders, due to these properties, it has been widely used in surface coating and imaging. Potential applications include use in memory devices, at temperatures below Tc=340 K, VO2 has a monoclinic crystal structure. Above Tc, the structure is tetragonal, like rutile TiO2, in the monoclinic phase, the V4+ ions form pairs along the c axis, leading to alternate short and long V-V distances of 2.65 Å and 3.12 Å. In comparison, in the phase the V4+ ions are separated by a fixed distance of 2.96 Å. As a result, the number of V4+ ions in the unit cell doubles from the rutile to the monoclinic phase. The equilibrium morphology of rutile VO2 particles is acicular, laterally confined by surfaces, the surface tends to be oxidized with respect to the stoichiometric composition, with the oxygen adsorbed on the surface forming vanadyl species.
The presence of V5+ ions at the surface of VO2 films has been observed by x-ray photoelectron spectroscopy measurements, the optical band gap of VO2 in the low-temperature monoclinic phase is about 0.7 eV. The thermal conductivity that could be attributed to electron movement was 10% of the amount predicted by the Wiedemann-Franz Law, the reason for this appears to be the fluidic way that the electrons move through the material, reducing the typical random electron motion. Potential applications include converting waste heat engines and appliances into electricity. Thermal conductivity varied when VO2 was mixed with other materials, at a low temperature it could act as an insulator, while conducting heat at a higher temperature. The origin of this insulator to metal transition remains controversial and is of interest in condensed matter physics, VO2 expresses temperature-dependent reflective properties. When heated from room temperature to 80 °C, the thermal radiation rises normally until 74 °C.
At room temperature VO2 is almost transparent to infrared light, as its temperature rises it gradually changes to reflective. At intermediate temperatures it behaves as a highly absorbing dielectric, a thin film of vanadium oxide on a highly reflecting substrate such as sapphire is either absorbing or reflecting, dependent on temperature. Its emissivity varies considerably with temperature, when the vanadium oxide transitions with increased temperature, the structure undergoes a sudden decrease in emissivity – looking colder to infrared cameras than it really is. Nanoscale structures that appear naturally in the transition region can suppress thermal radiation as the temperature rises
Halite, commonly known as rock salt, is a type of salt, the mineral form of sodium chloride. The mineral is colorless or white, but may be light blue, dark blue, pink, orange, yellow or gray depending on the amount. It commonly occurs with other evaporite minerals such as several of the sulfates, halides. Halite occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes, salt beds may be hundreds of meters thick and underlie broad areas. In the United States and Canada extensive underground beds extend from the Appalachian basin of western New York through parts of Ontario, other deposits are in Ohio, New Mexico, Nova Scotia and Saskatchewan. The Khewra salt mine is a deposit of halite near Islamabad. In the United Kingdom there are three mines, the largest of these is at Winsford in Cheshire producing on average a million tonnes per year. Salt domes are vertical diapirs or pipe-like masses of salt that have been squeezed up from underlying salt beds by mobilization due to the weight of overlying rock.
Salt domes contain anhydrite and native sulfur, in addition to halite and sylvite and they are common along the Gulf coasts of Texas and Louisiana and are often associated with petroleum deposits. Germany, the Netherlands and Iran have salt domes, salt glaciers exist in arid Iran where the salt has broken through the surface at high elevation and flows downhill. In all of these cases, halite is said to be behaving in the manner of a rheid, purple, fibrous vein filling halite is found in France and a few other localities. Halite crystals termed hopper crystals appear to be skeletons of the cubes, with the edges present and stairstep depressions on, or rather in. In a rapidly crystallizing environment, the edges of the cubes simply grow faster than the centers, halite crystals form very quickly in some rapidly evaporating lakes resulting in modern artifacts with a coating or encrustation of halite crystals. Halite flowers are rare stalactites of curling fibers of halite that are found in certain arid caves of Australias Nullarbor Plain, halite stalactites and encrustations are reported in the Quincy native copper mine of Hancock, Michigan.
Halite is often used both residentially and municipally for managing ice, because brine has a lower freezing point than pure water, putting salt or saltwater on ice that is near 0 °C will cause it to melt. It is common for homeowners in cold climates to spread salt on their sidewalks and driveways after a snow storm to melt the ice. It is not necessary to use so much salt that the ice is melted, rather. Also, many cities will spread a mixture of sand and salt on roads during, in addition to de-icing, rock salt is occasionally used in agriculture
Vanadyl sulfate, VOSO4, is a inorganic compound of vanadium. This very hygroscopic blue solid is one of the most common sources of vanadium in the laboratory and it features the vanadyl ion, VO2+, which has been called the most stable diatomic ion. Vanadyl sulfate is an intermediate in the extraction of vanadium from petroleum residues, vanadyl sulfate is a component of some food supplements and experimental drugs. Viewed as a complex, the ion is octahedral, with oxo, four equatorial water ligands. The V=O bond distance is 160 pm in length, about 50 pm shorter than the V–OH2 bonds, in solution, the sulfate ion dissociates rapidly. Reduction, e. g. by zinc, gives vanadium and vanadium derivatives, like most water-soluble sulfates, vanadyl sulfate is only rarely found in nature. Anhydrous form is pauflerite, a mineral of fumarolic origin, hydrated forms, include hexahydrate and trihydrate -. Treatment with vanadium often results in gastrointestinal side-effects, primarily diarrhea, vanadyl sulfate is marketed as a health supplement, often for body-building.
Since vanadium has no function in mammals this is a relatively controversial practice. Its effectiveness for body building has not been proven, some evidence suggests that athletes who take it are merely experiencing a placebo effect
Cobalt oxide is an inorganic compound with the formula Co3O4. It is one of two well characterized cobalt oxides and it is a black antiferromagnetic solid. As a mixed valence compound, its formula is written as CoIICoIII2O4. Co3O4 adopts the normal structure, with Co2+ ions in tetrahedral interstices. Cobalt oxide, CoO, converts to Co3O4 upon heating at around 600-700 °C in air, above 900 °C, CoO is stable. These reaction are described by the equilibrium,2 Co3O4 ⇌6 CoO + O2 Cobalt compounds are potentially poisonous in large amounts
Vanadium trichloride is the inorganic compound with the formula VCl3. This purple salt is a precursor to other vanadium complexes. VCl3 has the common BiI3 structure, a motif that features hexagonally closest-packed chloride framework with vanadium ions occupying the octahedral holes, vBr3 and VI3 adopt the same structure, but VF3 features a structure more closely related to ReO3. VCl3 is paramagnetic and has two unpaired electrons, VCl3 is prepared by heating VCl4 at 160–170 °C under a flowing stream of inert gas, which sweeps out the Cl2. The bright red liquid converts to a crusty purple solid, further heating of VCl3 decomposes with volatilization of VCl4, leaving VCl2. Upon heating under H2 at 675 °C, VCl3 reduces to greenish VCl2, VCl3 dissolves in water to give the hexahydrate, but the formula is deceptive. The salt is described by the formula Cl. 2H2O, in other words, two of the water molecules are not bound to the vanadium, whose structure resembles the corresponding Fe derivative. Removal of the two chloride ligands from + in aqueous solution gives the green ion 3+.
With tetrahydrofuran, VCl3 forms the red/pink adduct VCl33, with acetonitrile, one obtains the green adduct VCl33. When treated with KCN, VCl3 converts to 4− and it is common for early metals to adopt high coordination numbers with compact ligands. Complementarily, larger metals can form complexes with rather bulky ligands and this aspect is illustrated by the isolation of VCl32, containing two bulky NMe3 ligands. The reactive species V3 forms from VCl3, VCl33 +3 LiC6H2-2,4, 6-Me3 → V3 +3 LiCl This species binds CO and, under appropriate conditions, N2