ABSTRACT
Epoxidation of 2-cyclohexen-1-ol with a 20 wr'lo Ti02 - 80 wr'lo Si02 aerogel and tert-butylhydroperoxide was studied. Rapid consumption of2-cyclohexen-lol was due to acid-catalyzed, non-oxidative side reactions of the ally tic alcohol, the epoxide representing a product in only low amount. Epoxide selectivities related to allylic alcohol, Scme. could be improved remarkably and acid-catalyzed side reactions suppressed by addition of amines. The best modifier was tritylamine (Ph3CNHv; 1 mol% amine (related to allylic alcohol) improved the epoxide selectivity Se=c from 22 % to 81 %, while maintaining the high rate of epoxide formation. It was found that amine additives have a much stronger positive effect on selectivities than application of lower reaction temperature and the use of a weakly basic solvent. The method of amine addition was also applied to the epoxidation of the bishomoallylic alcohol 3-cyclohexen-l-methanol.
