The SN mechanism in aromatic compounds. Part XL. Activating effects of groups attached to the ring by a sulphur atom
Abstract
Kinetic data are presented for the alkaline methanolysis of a series of 4-substituted fluorobenzenes, in which the substituents are joined to the ring through sulphur, viz. SMe, SPh, SCF3, SOMe, SO2Me, SO2Ph, and SO2CF3. The Hammett substituent constants (σ–) estimated at 100° are: 0.27; 0.36; 0.66; 0.77; 1.00; 1.04: 1.40. These are compared with values for COMe, NO, and NO2groups. It is suggested that in the sequence of saturated groups SCH3to SCF3, a small conjugative effect becomes evident. The possibility of a favourable polarizability effect is also considered. The ability of SR groups to activate both SE and SNAr reactions is discussed and brief comparison made with OR groups.
Please wait while we load your content...
