Reactions of organic peroxides. Part XV. Conversion of cyclohexanone into hexan-6-olide

Methods for the conversion of cyclohexanone into hexan-6-olide in high yield have been studied. A process involving the use of peroxymaleic acid is described, in which the formation of cyclohexanone peroxides is avoided. By treatment with formic acid all the cyclohexanone peroxides were converted into 6-formyloxyhexanoic acid, from which caprolactone was obtained by a catalysed thermal reaction. The preformed cyclohexanone peroxides for this reaction could be replaced by cyclohexanol autoxidate or by the product obtained by treatment of cyclohexanone with photo-oxidised propan-2-ol.