Ethylene adduct of conjugated octadecadienoic acids: II. Ozonization products

Methyl 8‐(4‐n‐hexylcyclohex‐2‐enyl) octanoate obtained by esterifying the adduct of ethylene andtrans,trans‐9,11‐octadecadienoic acid was ozonized in methanol as a participating solvent. The resultant cyclic methoxyhemiperacetal was reduced with powdered zinc to the dialdehyde, methyl 9,12‐diformylstearate, which was isolated as the tetramethyldiacetal. This dialdehyde readily air‐oxidizes to give methyl 9,12‐dicarboxystearate. Heating the cyclic methoxyhemiperacetal slowly from 25 to 100 C in vacuo results in an unusual decomposition reaction which gives hydrogen and methyl 9 (12)‐carbomethoxy‐12(9)‐carboxystearate as the primary products and methyl 9 (12)‐carbomethoxystearate as the major by‐product. Treatment of the cyclic hemiperacetal with hydrogen peroxide in formic acid gave unexpectedly dihydroxystearic acid as one of the products.