Studies of pyrazines. Part 8. Pyrolysis of 2-alkoxypyrazines; substituent effects and stereospecificity

Abstract

Twelve 2-alkoxypyrazines (R = Prⁱ, Bu^s, 1,2-dimethylpropyl, 1,2,2-trimethylpropyl, t-butyl, t-pentyl, 1,1,2-trimethylpropyl, 1,1,2,2-tetramethylpropyl, octyl, neopentyl, ±-erythro- and ±-threo-2-deuterio-1,2-diphenylethyl) have been pyrolysed to elucidate the substituent effects on the rate and stereospecificity of the reaction. Activation parameters (log A and E_a) for the first eight compounds listed were determined. The reaction was accelerated by α-substitution; this was a combination of both polar and steric effects. The stereospecificity of the reaction was high.