GB608539A - A process for the oxidation of cyclic ethers - Google Patents

Abstract

Aliphatic lactones are produced by oxidising cyclic ethers containing one oxygen atom and four or five carbon atoms in the ring, the groups adjacent to the oxygen atom being methylene groups, in the liquid phase at elevated temperature by means of a gas containing free oxygen. Suitable temperatures are 70 DEG -200 DEG C. and increased pressures, e.g. up to 10 atmospheres gauge may be employed. Oxidation catalysts comprising metal compounds or organic compounds may be used, e.g. compounds of cobalt, manganese, iron, cerium lead, copper and chromium; organic acid salts of the metals, e.g. the salts of mono-carboxylic acids, such as the stearates, linoleates, naphenates and acetates and particularly cobalt stearate. Benzoyl peroxide is also suitable. An inert solvent may be used, e.g. acetic acid or benzene. In examples: (1) tetrahydrofuran and cobalt naphthenate are heated under pressure, the product is distilled to give a -butyrolactone; (2) tetrahydropyran, cobalt naphthenate and cyclohexane are heated in an autoclave and a stream of air passed through the mixture. Distillation of the product yields a -valerolactone and some formic acid; (3) a -butyrolactone is obtained as in (1), but without the use of a catalyst. 2,5-Dihydrofuran is also specified and yields the lactone of a -hydroxy crotonic acid.