Chromium compounds ketones

Chromium compounds decompose primary and secondary hydroperoxides to the corresponding carbonyl compounds, both homogeneously and heterogeneously (187—191). The mechanism of chromium catalyst interaction with hydroperoxides may involve generation of hexavalent chromium in the form of an alkyl chromate, which decomposes heterolyticaHy to give ketone (192). The oxidation of alcohol intermediates may also proceed through chromate ester intermediates (193). Therefore, chromium catalysis tends to increase the ketone alcohol ratio in the product (194,195). 

Chromium compounds used in catalytic amounts for the oxidation of alcohols to aldehydes and ketones include ... 

Chromium speciation has also been successfully achieved by using SFC [99]. Two p-ketonate chromium compounds and an organochromium dimer were separated initially, using C02 as the mobile phase. However, as a result of an isobaric interference at m/z 52 (the major chromium isotope) from the formation of 40Ar12C+, nitrous oxide was used instead. 

Alkenes can be oxidized to ketones of the same chain length by using salts of copper, palladium, and mercury as catalysts and air, electrolysis [120], hydrogen peroxide, or chromium compounds as oxidants [60, 65, 140, 565] (equation 90). 

If the oxidation of the boranes is carried out by hexavalent chromium compounds, the products are aldehydes (equation 602) [611] or ketones (equation 603) [646]. 

AMINOETHYLETHANDIAMINE (111-40-0) Combustible liquid (flash point 208°F/ 98°C oc). An organic base. Ignites spontaneously with cellulose nitrate, and possibly other nitrogen compounds. Silver, cobalt, or chromium compounds may cause explosions. Contact with nitromethane forms a heat-, friction-, and shock-sensitive explosive. Incompatible with acids, acrylates, aldehydes, alcohols, alkylene oxides, caprolactam solution, cresols, organic anhydrides, substituted allyls, epichlorohydrin, glycols, halogenated compounds, isocyanates, ketones, mercury, phenols, strong oxidizers, vinyl acetate. Attacks aluminum, copper, cobalt, lead, tin, zinc, and their alloys. 

This reaction was initially reported by Etard in 1880. It is the oxidation of hydrocarbons by hexavalent chromium compounds (chromyl chloride, i.e., chromatic acid chloride) to form a mixture of alcohol, carbonyl compounds (aldehyde or ketones), chloro-ketones, or aldehydes and the starting material. Therefore, this reaction is generally known as the Etard... 

Dipyridiue-chromium(VI) oxide2 was introduced as an oxidant for the conversion of acid-sensitive alcohols to carbonyl compounds by Poos, Arth, Beyler, and Sarett.3 The complex, dispersed in pyridine, smoothly converts secondary alcohols to ketones, but oxidations of primary alcohols to aldehydes are capricious.4 In 1968, Collins, Hess, and Frank found that anhydrous dipyridine-chromium(VI) oxide is moderately soluble in chlorinated hydrocarbons and chose dichloro-methane as the solvent.5 By this modification, primary and secondary alcohols were oxidized to aldehydes and ketones in yields of 87-98%. Subsequently Dauben, Lorber, and Fullerton showed that dichloro-methane solutions of the complex are also useful for accomplishing allylic oxidations.6... 

Dermal Effects. Skin irritation was noted in wildlife officers at the RMA after they handled sick or dead ducks without gloves (NIOSH 1981). Although the investigators concluded that diisopropyl methylphosphonate contributed to the local effects, a number of other compounds were present. Analysis of the pond water indicated the presence of a number of organic and inorganic contaminants, including diisopropyl methylphosphonate (11.3 ppm) aldrin (0.368 ppm) dieldrin (0.0744 ppm) dicyclo-pentadiene, bicycloheptadiene, diethyl benzene, dimethyl disulfide, methyl acetate, methyl isobutyl ketone, toluene, and sodium (49,500 ppm) chloride (52,000 ppm) arsenic (1,470 ppm) potassium (180 ppm) fluoride (63 ppm) copper (2.4 ppm) and chromium (0.27 ppm). Because of the presence of numerous compounds, it is unclear whether diisopropyl methylphosphonate was related to the irritation. 

Oxidation of that compound with chromium trioxide in sulfuric acid leads cleanly to the desired ketone (67). Treatment with hydrobromic acid serves to demethylate the phenolic ether function (68). Direct... 

Hydrogen transfer reactions from an alcohol to a ketone (typically acetone) to produce a carbonyl compound (the so-caUed Oppenauer-type oxidation ) can be performed under mild and low-toxicity conditions, and with high selectivity when compared to conventional methods for oxidation using chromium and manganese reagents. While the traditional Oppenauer oxidation using aluminum alkoxide is accompanied by various side reactions, several transition-metal-catalyzed Oppenauer-type oxidations have been reported recently [27-29]. However, most of these are limited to the oxidation of secondary alcohols to ketones. 

Catalysts suitable specifically for reduction of carbon-oxygen bonds are based on oxides of copper, zinc and chromium Adkins catalysts). The so-called copper chromite (which is not necessarily a stoichiometric compound) is prepared by thermal decomposition of ammonium chromate and copper nitrate [50]. Its activity and stability is improved if barium nitrate is added before the thermal decomposition [57]. Similarly prepared zinc chromite is suitable for reductions of unsaturated acids and esters to unsaturated alcohols [52]. These catalysts are used specifically for reduction of carbonyl- and carboxyl-containing compounds to alcohols. Aldehydes and ketones are reduced at 150-200° and 100-150 atm, whereas esters and acids require temperatures up to 300° and pressures up to 350 atm. Because such conditions require special equipment and because all reductions achievable with copper chromite catalysts can be accomplished by hydrides and complex hydrides the use of Adkins catalyst in the laboratory is very limited. 

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