Oxidative cleavage of secondary alcohols and ketones

Oxidative cleavage is clearer-cut when one of the carbon atoms in -position to the carbonyl group is that of a methyl group (see below) or carries no hydrogen (as in alkyl aryl ketones) the oxidant then attacks only at the side where the -methylene or methine group lies. Ditertiary ketones such as benzo-phenone are therefore almost completely stable against oxidation. 

Greater preparative importance attaches to oxidative ring opening of cycloalkanols and cycloalkanones, which then afford alkanedioic acids containing an unchanged number of carbon atoms. Thus, for instance, adipic acid is obtained in up to 90% yield from cyclohexanol or cyclohexanone by means of about 60% nitric acid containing vanadium and copper salts as catalyst 125 

Ammonium vanadate (0.32 part) and copper turnings (0.4 part) are warmed with 60% nitric acid (301 parts) at 55°, then cyclohexanol (100 parts) is added gradually at 55-60° 

The action of peroxyacids, such as Caro s acid, on cyclic ketones affords co-hydroxy carboxylic acids or their lactones, the latter being convertible into co-hydroxy carboxylic esters by the action of an alcohol and an acid cyclohexanone, for instance, gives a 6-hydroxyhexanoic ester in this way 126,127 

Frequent use is made in the laboratory of oxidative degradation of methyl ketones. With alkyl ketones the resistance of the methyl group to attack by the usual oxidants is so great that reaction occurs only at one point thus an unbranched alkyl methyl ketone, for instance, on oxidation by chromic and sulfuric acid in glacial acetic acid affords, besides acetic acid, the alkanoic acid containing two fewer carbon atoms than the ketone e.g., palmitic acid from 2-octadecanone 128 

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