Oxidation of Primary Alcohols to Esters

In acidic oxidations of primary alcohols, esterification of the alcohol by the acid produced by its oxidation sometimes takes place. Thus the oxidation of ethanol with potassium peroxymonosulfate (Oxone) in the presence of concentrated sulfuric acid at 70 °C gives a quantitative yield of ethyl acetate [205]. 

Butyl alcohol treated with sodium dichromate and sulfuric acid at 

20-35 °C furnishes a 41-47% yield of butyl butyrate [640]. Butyl butyrate is also obtained in 82% yield by oxidation of butanol by bromine and potassium bromate in 40% hydrobromic acid [742] (equation 237). 

The oxidation of aliphatic alcohols in benzene or petroleum ether with /ert-butyl chromate at 1-2 °C for 6 h leads to mixtures of aldehydes, acids, and their esters. Butanol gives 30% of butanal, 27% of butyric acid, and 36% of butyl butyrate [677], Also, electrolysis of aliphatic alcohols on platinum or carbon electrodes in aqueous potassium iodide at room temperature results in 80-83% yields of the corresponding esters [121]. 

Ester formation is especially easy in oxidations of diols (with at least one primary hydroxyl group) that can cyclize to five- or six-membered lactones after partial oxidation [355, 1035] see equations 292-295). 

---

Potassium bromate, KBrOa, and hydrobromic acid are used in the in situ generation of bromine for the oxidation of primary alcohols to esters [742]. 

---