ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 32, Number 3
JKCSEZ 32(3)
June 20, 1988 

The rate constants for the nucleophilic addition reactions of thioglycolic acid and cysteine to β, β-dichlorostyrene derivatives(p-H, p-Cl, p-CH3, and p-OCH3) were photochemically determined at various pH and a rate equation which can be applied over a wide pH range was obtained. On the bases of rate equation, general base catalysis and substituent effect, the plausible addition reaction mechanism was proposed: Above pH 9.0, the reaction was initiated by the addition of sulfide anion, and in the range of pH 7.0 to 9.0, the neutral molecules and it's anions attacked to the double bond, competitively. However, below pH 7.0, only the neutral molecules of thioglycolic acid or cysteine added to the carbon-carbon double bond.