The Hydrolysis of p-Substituted Styrene Oxides 77
Answer to the Question
Additional evidence in favor of the intermediacy of a carbocation in the acid solvolysis of styrene oxides could be obtained from a trapping experiment. In order
to increase the lifetime of the carbocation, it would be convenient to use a p-MeOsustituted styrene oxide as substrate and very little nucleophilic solvent. The trapping agent should be very reactive and much more nucleophile than the solvent, to
avoid any undesirable competition reaction between both species. The highly nucleophile azide ion could be suitable to trap the intermediate which has sufficiently long lifetimes in aqueous solutions to be trapped by the reagent (Scheme
11.8).
O
Ar
H
O
Ar
H
H
CH 2 OH
Ar
H
H +
ArCH CH 2 OH
N 3
1
NaN 3
Ar = p-MeOC 6 H 4
Scheme 11.8
Additional Comments
This problem is based on the work by Blumenstein JJ, Ukachukwu VC, Mohan
RS, Whalen DL (1993) J. Org. Chem. 58:924-932.
Subjects of Revision
Catalysis, types and mechanisms. Hammett U and V constants. S N 1 versus S N 2 reactions. Carbocations.