A study of the OH- -induced beta-elimination reactions of 2-(4-chloroethyl)pyridine, 2-(2-chloroethyl)pyridine, 1-methyl-2-(4-chloroethyl)pyridinium iodide and 1-methyl-2-(2-chloroethyl)pyridinium iodide in acetonitrile/water.
Second-order rate constants have been determined for the title reactions in OH(-)/H(2)O and in OH(-)/ (CH(3)CN/H(2)O) [30/70, 60/40, and 85/15 (v/v) mixtures]. A relatively small increase in reactivity is observed for the four substrates upon increasing the percentage of CH(3)CN in the solvent mixture. The methyl activating factors (/) are also slightly affected by the solvent composition. On the other hand, the high acceleration of the reaction by methylation of the pyridine ring amounts to 10(4)-10(6) according to an E1cb mechanism.
Alunni
Sergio
S
Dipartimento di Chimica, Università degli Studi Perugia, Via Elce di Sotto 8, 06123 Perugia Italy. alunnis@unipg.it
Del Giacco
Tiziana
T
De Maria
Paolo
P
Fontana
Antonella
A
Gasbarri
Carla
C
Ottavi
Laura
L