IN-SITU C-13 NMR-STUDY OF TERT-BUTANOL INTERACTION WITH MODERATELY CONCENTRATED SULFURIC-ACID

An in situ NMR study of tert-butanol dehydration in 95 and 85% sulfuri c acid did not indicate the formation of tert-butyl cations as active reaction intermediates. Instead, only NMR lines from oxonium ions unde r the condition of fast exchange with water and the acid were observed . It is most likely that, in the concentrated acid, the active interme diates of this reaction are represented by tert-butyl sulfuric ester w hich probably is a precursor of invisible tert-butyl carbenium ions re presenting short-lived excited or transition states.