Chromium 11 perchlorate

Group 6 (VIB) Perchlorates. Both divalent and trivalent chromium perchlorate compounds [13931 -95-8 13527-21 -9] have been reported. Anhydrous chromyl perchlorate [60499-74-3] has been prepared ia the cold ... 

Chromium Perchlorate.—By dissolving chromium hydroxide in perchloric acid, and subsequent cautious evaporation, short green deliquescent needles of chromium perchlorate, soluble in alcohol, arc obtained. Two bluish-green perchlorates, probably derivatives of the hex-aquo base, [Cr(H20)e](0104)3 and [Cr(H20)6](C104)3.3lI 0, liave been described. ... 

Chromium contributes to organic transformations as reagents. Some examples include chromic acid Qones reagent), chromium acetate for the reduction of carbon-halogen bonds and conversion of ketoximes to ketones, chromyl acetate, chromium perchlorate, chromium sulfate (reduction of allq nes to alkenes), and Jacob s reagent (Cr02Cl2). The catalytic... 

On an alternative pathway, internal Cannizzaro reactions afford mandelic acid-type compounds from phenylglyoxal derivatives [152-156]. Copper complexes [153, 154], chromium perchlorate [154], cobalt Schiff s bases [155] and yttrium chloride [156] have been applied as catalysts. An asymmetric version [Eq. (7)] has been developed using phenylglyoxal (14) as substrate and a combination of Cu(OTf)2 and (S,S)-Ph-box 16 as the chiral catalyst [154]. After 24 h at room temperature isopropyl man-delate (15) was obtained with an enantioselectivity of 28% ee. 

Acetic acid Chromium(VI) oxide, chlorosulfonic acid, ethylene glycol, ethyleneimine, hydroxyl compounds, nitric acid, oleum, perchloric acid, peroxides, permanganates, potasssium r rf-butoxide, PCI3... 

Ammonia, anhydrous Mercury, halogens, hypochlorites, chlorites, chlorine(I) oxide, hydrofluoric acid (anhydrous), hydrogen peroxide, chromium(VI) oxide, nitrogen dioxide, chromyl(VI) chloride, sulflnyl chloride, magnesium perchlorate, peroxodisul-fates, phosphorus pentoxide, acetaldehyde, ethylene oxide, acrolein, gold(III) chloride... 

Ethyl ether Eiquid air, chlorine, chromium(VI) oxide, lithium aluminum hydride, ozone, perchloric acid, peroxides... 

Glycerol Acetic anhydride, hypochlorites, chromium(VI) oxide, perchlorates, alkali peroxides, sodium hydride... 

Pyridine Chlorosulfonic acid, chromium trioxide, formamide, maleic anhydride, nitric acid, oleum, perchromates, silver perchlorate, sulfuric acid... 

By monitoring the intensity of the carbonyl absorption it was observed that oxidation of methyl 4,6-0-benzylidene-2-deoxy-a-D-Zt/ ro-hexopyrano-side with chromium trioxide-pyridine at room temperature gave initially the hexopyranosid-3-ulose (2) in low concentration, but attempts to increase this yield resulted in elimination of methanol to give compound 3. However, when methyl 4,6-0-benzylidene-2-deoxy-a-D-Zt/ ro-hexo-pyranoside is oxidized by ruthenium tetroxide in either carbon tetrachloride or methylene dichloride it affords compound 2 without concomitant elimination. When compound 2 was heated for 30 minutes in pyridine which was 0.1 M in either perchloric acid or hydrochloric acid it afforded compound 3, but in pyridine alone it was recoverable unchanged (2). Another example of this type of elimination, leading to the introduction of unsaturation into a glycopyranoid ring, was observed... 

Large amounts of chloride, cobalt(II), and chromium(III) do not interfere iron(III), nickel, molybdenum)VI), tungsten(VI), and uranium(VI) are innocuous nitrate, sulphate, and perchlorate ions are harmless. Large quantities of magnesium, cadmium, and aluminium yield precipitates which may co-precipitate manganese and should therefore be absent. Vanadium causes difficulties only... 

Chromium in steel Discussion. The chromium in the steel is oxidised by perchloric acid to the dichromate ion, the colour of which is intensified by iron (III) perchlorate which is itself colourless. The coloured solution is compared with a blank in which the dichromate is reduced with ammonium iron(II) sulphate. The method is not subject to interference by iron or by moderate amounts of alloying elements usually present in steel. 

Standardisation may be carried out by the use of solutions prepared from a chromium-free standard steel and standard potassium dichromate solution. After dissolution of the standard steel, the solution is boiled with perchloric... 

The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

The kinetics of the oxidation of chromium(II) by vanadium(ni) in acid perchlorate media have been studied spectrophotometrically between 0.2° and 35.0 °C over a range of 0.027-0.500 M HC104 . The oxygen-sensitivity of both reactants meant that the air had to be excluded in all kinetic runs. Also, since V(III) slowly reduces perchlorate ion, fresh solutions of V(III) were required for each experiment. In terms of stoichiometry the reaction conforms accurately to... 

The stoichiometric equation for oxidation of vanadium(IV) by chromium(Vl) in acid perchlorate solutions is essentially... 

To decide whether the reaction involves 1- or 2-electron transfers, i.e. chromium-(rv) or chromium(V) is formed first, the induced oxidation of manganese(II) was investigated. When sodium perchlorate was used to maintain a constant ionic strength, the rate of oxidation of benzaldehyde dropped to one-half of the original rate in the presence of manganese(II) ions. On the contrary, when magnesium perchlorate was used as the neutral salt, the rate was reduced to of its original value. This peculiar observation, however, has not been interpreted. 

Redox titrants (mainly in acetic acid) are bromine, iodine monochloride, chlorine dioxide, iodine (for Karl Fischer reagent based on a methanolic solution of iodine and S02 with pyridine, and the alternatives, methyl-Cellosolve instead of methanol, or sodium acetate instead of pyridine (see pp. 204-205), and other oxidants, mostly compounds of metals of high valency such as potassium permanganate, chromic acid, lead(IV) or mercury(II) acetate or cerium(IV) salts reductants include sodium dithionate, pyrocatechol and oxalic acid, and compounds of metals at low valency such as iron(II) perchlorate, tin(II) chloride, vanadyl acetate, arsenic(IV) or titanium(III) chloride and chromium(II) chloride. 

See Barium perchlorate Alcohols Bromine Alcohols Chlorine Methanol Chromium trioxide Alcohols... 

See Chromium(III) perchlorate. 6 dimethyl sulfoxide Magnesium perchlorate Dimethyl sulfoxide Mercury(II) perchlorate. 6(or 4)dimethyl sulfoxide Silver perchlorate Dimethyl sulfoxide See Perchloric acid Sulfoxides... 

A wet-ashing technique used for dissolution of graphite in perchloric acid involved boiling a mixture of 70% perchloric acid and 1% of chromium trioxide as an aqueous solution. This method was later applied to 6-14 mesh charcoal, and after boiling for 30 min the reaction rate increased (foaming) and accelerated to explosion. The charcoal contained traces of extractable tar. 

Hydroxylamine is a powerful reducant, particularly when anhydrous, and if exposed to air on a fibrous extended surface (filter paper) it rapidly heats by aerobic oxidation. It explodes in contact with air above 70°C [1]. Barium peroxide will ignite aqueous hydroxylamine, while the solid ignites in dry contact with barium oxide, barium peroxide, lead dioxide and potassium permanganate, but with chlorates, bromates and perchlorates only when moistened with sulfuric acid. Contact of the anhydrous base with potassium dichromate or sodium dichromate is violently explosive, but less so with ammonium dichromate or chromium trioxide. Ignition occurs in gaseous chlorine, and vigorous oxidation occurs with hypochlorites. 

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