Syntheses of cis‐ and trans‐7‐ and 8‐octadecenoic acids: Comparison of the properties of cis‐ and trans‐6‐, 7‐, 8‐, 9‐, and 11‐octadecenoic acids

Summary 1. The cis‐ and trans‐modifications of 7‐, 8‐, and 11‐octadecenoic acids were synthesized by methods which leave no doubt as to their structure. 2. Many new compounds have been reported including 7‐octadecynoic acid, 8‐octadecynoic acid. 7,8‐diketostearic acid, 8,9‐diketostearic acid, cis‐ and trans‐7‐octadecenoic acids and their 7,8‐dihydroxystearic acid derivatives, and cis‐ and trans‐8‐octadecenoic acid derivatives and their 8,9‐dihydroxystearic acid derivatives. 3. A new series of intermediate reaction products has been reported although these compounds were not fully characterized. These compounds include hexamethylene bromochloride, hexamethylene iodochloride, 1‐chloro‐6‐heptadecyne, and 1‐chloro‐7‐heptadecyne. 4. The extinction coefficients at 10.36 microns of the cis and trans‐6‐, 7‐, 8‐, 9‐, and 11‐octadecenoic acids have been calculated and compared. 5. The melting points of the cis‐ and trans‐octadecenoic acids and their dihydroxy derivatives were shown to exhibit alternating patterns.