Chromium acetylacetonate carbonyl

Under the same conditions, cobalt acetylacetonate afforded a mixture of four products the mono-, di-, and triacetylated chelates (XVII, XVIII, and XIX), along with the starting material. In contrast to the chromium chelates, the mixture of cobalt complexes was cleanly separated by chromatography. The identity of each of these products was established by an NMR spectrum. The presence of uncoordinated carbonyl groups was revealed by infrared absorption at 1675 cm.-1... 

Chromium hexacarbonyl is extremely photolabile (equation 6) therefore photochemical substitution is an efficient means of preparing derivatives. Oxidation of the Cr center requires nitric or sulfuric acid, or chlorine. Alternatively, some hgands induce complete carbonyl dissociation with concomitant oxidation, for example, acetylacetonate. Chemical reduction with alkali or alkaline-earth metals or electrochemical reduction proceeds in two-electron steps with loss of two CO molecules to first give [Cr2(CO)io]" and then [Cr(CO)s]. Nucleophilic attack at CO generates a number of stable (Nu = R) and unstable (Nu = N3, OH, H, NEt2) products. The stable [(OC)5CrCOR] ion is a carbene precursor. 

Although the chromium hexacarbonyl necessary for this preparation may be obtained by the method described in an earlier synthesis, several improved procedures have been developed recently. Of these, the carbonylation of a mixture of chromium (III) acetylacetonate [2,4-pentanedionato-chromium(III)], magnesium, and pyridine in the presence of catalytic quantities of iodine, or the carbonylation of a mixture of chromium(III) chloride, aluminum chloride,... 

Secondary alcohols are oxidized by H5IO6 in the presence of various chromium catalysts to ketones [1321-1325], while primary alcohols can be oxidized to aldehydes or to carboxylic acids depending on the catalyst. Primary alcohols in the presence of pyridinium chlorochromate (PCC)[1322] or chromium (III) acetylacetonate, Cr(acac)3 [1321] are oxidized to aldehydes or ketones in excellent yields, while the use of CrOj [1326,1327] or pyridinium fluorochromate [1323] as catalysts results in the oxidation to carboxylic acids. The periodic acid promoted oxidation of primary and secondary alcohols to carbonyl compounds can also be catalyzed by Cu(II) derivatives [1328,1329], by bromide anion [1330] and by TEMPO [1331]. 

Oxalic acid Oxalic acid dihydrate catalyst, nylon Manganese acetate (ous) catalyst, olefin isomerization Iron pentacarbonyl catalyst, olefin polymerization Acetylacetone Ammonium lactate Chromium carbonyl Chromium chloride (ic) Ethylacetoacetate... 

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