Kinetics of piperidino- and benzenethiolate-dehalogenation of some 4-substituted 2,3-dihalogeno-5-nitrothiophens in methanol
Abstract
The reactivity of 2,3-dihalogeno-4-R-5-nitrothiophens [R = H (I) and Me (II); halogen = Cl (b) and I (c)] with piperidine and sodium benzenethiolate has been studied in methanol at various temperatures. The results obtained together with previous data concerning 2,3-dibromo-4-R-5-nitrothiophens [R = H (I) and Me (II)] and 2-halogeno-5-nitrothiophens [(IV); halogen = Br (a), Cl (b), and I (c)] have shown that the activating effect of the 3-halogen substituent is largely affected by the nature of both halogen and nucleophile, and furnished further examples of weak activation by a meta-methyl group.