Abstract
Esters of β-mercaptothiocinnamic acid were prepared as strong chelating agents. Phenylpropioloyl chloride was converted into alkyl or aryl phenylthiopropiolate and thiourea was reacted in the presence of p-toluenesulfonic acid to obtain corresponding isothiuronium salts. Esters of β-mercaptothiocinnamic acid were obtained by the hydrolyses of the isothiuronium salts. Thioxo-thioenol tautomerism in the esters of β-mercaptothiocinnamic acid was investigated by infrared and nuclear magnetic resonance spectroscopy. It was found that cis-thioenol form is predominant and hence the mercapto group and the carbonyl group are markedly hydrogen-bonded.
