Kinetics of reactions in heterocycles. Part XI. Reactions of 2-, 6-, and 8-chloro-7-methylpurines and 2-, 6-, and 8-methylsulphonyl-7(and 9)-methylpurines with hydroxide ions

Abstract

Kinetics have been measured for the reactions of 6- and 8-chloro-7-methylpurine and 2-, 6-, and 8-methylsulphonyl-7(and 9)-methylpurine with hydroxide ions. Generally, at 20°, the 7-methylpurines were more reactive than their 9-methyl isomers, but 2-methylsulphonyl-9-methylpurine was 3· times more reactive than its 7-methyl isomer. Relative reactivities of the 2-, 6-, and 8-methylsulphonyl-7-methylpurines were 1 : 840 : 29,000, and for the 9-methyl series 1 : 110 : 830. Preparations of 2-, 6-, and 8-methylsulphonyl-7-methylpurine are described. Ionisation constants and u.v. and ¹H n.m.r. spectra are recorded and discussed.