ORIENTATION OF OLEFIN-FORMING ELIMINATION IN REACTIONS OF 2-SUBSTITUTED HEXANES WITH POTASSIUM T-BUTOXIDE-T-BUTYL ALCOHOL AND SODIUM METHOXIDE-METHANOL

Reactions of 13 2-substituted hexanes with t-BuO K+-t-BuOH and of 10 of the same substrates with NaOCH3-CH3OH are studied. Compositions of the olefin mixtures formed under conditions in which olefin isomerization is negligible are determined. In t-BuO“K+-t-BuOH, three 2-hexyl arenesulfonates, 2-hexyl 2,4,6-trimethylbenzoate, 2-hexyl phenyl sulfone, and 2-hexyl diphenyl phosphate give more cis- than trans-2-hexene, but all substrates studied give more trans- than cis-2-hexene in NaOCH3-CH3OH. Hofmann orientation predominates with all substrates in t-BuO-K+-t-BuOH, and is more accentuated from the 2-hexyl halides than from the 2-butyl halides in the same base-solvent system. Most of the observations of both positional and geometrical orientation are in accord with the theory of the variable E2 transition state, but the preferential formation of cis- over zrans-2-hexene from certain substrates is thought to be of steric origin. © 1969, American Chemical Society. All rights reserved.