Abstract
β-Mercaptocinnamamides were prepared as strong chelating agents. Phenylpropioloyl chloride was converted into alkyl- or arylamides, and thiourea was reacted in the presence of p-toluenesulfonic acid to obtain corresponding isothiuronium salts. β-Mercaptocinnamamides were obtained by the hydrolyses of the isothiuronium salts. Thioxo-thioenol tautomerism in the β-mercaptocinnamamides was investigated by infrared and nuclear magnetic resonance spectroscopy. It was found that cis-thioenol form is predominant in these amides but some differences were observed between alkylamides and arylamides. The arylamides were considered to have stronger chelating abilities than the alkylamides judging from their chemical properties, and this difference would be attributed to the difference in thioxo-thioenol tautomerism.
