Oxidation of alcohols PCC is used as an
oxidant. In particular, it has proven to be highly effective in
oxidizing primary and secondary alcohols to
aldehydes and
ketones, respectively. The reagent is more selective than the related
Jones' Reagent, so there is little chance of over-oxidation to form
carboxylic acids if acidified
potassium permanganate is used as long as water is not present in the reaction mixture. A typical PCC oxidation involves addition of an alcohol to a suspension of PCC in
dichloromethane. The general reaction is: :2 [C5H5NH][CrO3Cl] + 3 R2CHOH → 2 [C5H5NH]Cl + Cr2O3 + 3 R2C=O + 3 H2O For example, the
triterpene lupeol was oxidized to
lupenone: :
Babler oxidation With tertiary alcohols, the
chromate ester formed from PCC can isomerize
via a sigmatropic reaction|[3,3]-sigmatropic reaction and following oxidation yield an enone, in a reaction known as the Babler oxidation: This type of oxidative transposition reaction has been synthetically utilized,
e.g. for the synthesis of
morphine. Using other common oxidants in the place of PCC usually leads to dehydration, because such alcohols cannot be oxidized directly.
Other reactions PCC also converts suitable unsaturated alcohols and aldehydes to
cyclohexenones. This pathway, an oxidative
cationic cyclization, is illustrated by the conversion of (−)-
citronellol to (−)-
pulegone. PCC also effects
allylic oxidations, for example, in conversion of
dihydrofurans to
furanones. ==Related reagents==