Mechanism of oxidation R一C-O-H+H-O 0H→ RC—O— OH H,O H alcohol chromic acid chromate ester The alcohol and chromic acid produce a chromate ester,which then reductively eliminates the Cr species. The Cr is reduced (VI->IV),the alcohol is oxidized. R R R- Cr-OH R-C=0: Ci-OH H,O:H .0.4 HO+ 0 Cr(VI) Cr(IV) Oxidation of Primary Alcohols Primary alcohols are easily oxidized just like secondary alcohols,but the product of oxidation is an aldehyde RY十HOLRH回 OH 0 0 R--OH primary aldehyde acid alcohol However,the aldehyde can also be easily oxidized to an acid,and this 'over-oxidation'is a practical problem. ChlI Reacns of Alcohols (landscape) Page 3Ch11 Reacns of Alcohols (landscape) Page 3 Mechanism of oxidation The alcohol and chromic acid produce a chromate ester, which then reductively eliminates the Cr species. The Cr is reduced (VI IV), the alcohol is oxidized. Oxidation of Primary Alcohols Primary alcohols are easily oxidized just like secondary alcohols, but the product of oxidation is an aldehyde. However, the aldehyde can also be easily oxidized to an acid, and this ‘over-oxidation’ is a practical problem. R OH H H R O H R O OH primary alcohol aldehyde acid [O] [O]