Photohydrolysis of a Halophenol in Sunlight: Critical Influence of Substitution Pattern

Abstract

While the herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) is comparatively stable in sunlight, its positional isomer, 3,5-dibromo-2-hydroxybenzonitrile, degrades rapidly via a highly selective photoaromatic substitution reaction, illustrating a critical influence of substitution pattern on electronic absorption properties and photochemical behaviour.