2-Mercaptothiazole, tautomerism

In the first chapter, devoted to thiazole itself, specific emphasis has been given to the structure and mechanistic aspects of the reactivity of the molecule most of the theoretical methods and physical techniques available to date have been applied in the study of thiazole and its derivatives, and the results are discussed in detail The chapter devoted to methods of synthesis is especially detailed and traces the way for the preparation of any monocyclic thiazole derivative. Three chapters concern the non-tautomeric functional derivatives, and two are devoted to amino-, hydroxy- and mercaptothiazoles these chapters constitute the core of the book. All discussion of chemical properties is complemented by tables in which all the known derivatives are inventoried and characterized by their usual physical properties. This information should be of particular value to organic chemists in identifying natural or Synthetic thiazoles. Two brief chapters concern mesoionic thiazoles and selenazoles. Finally, an important chapter is devoted to cyanine dyes derived from thiazolium salts, completing some classical reviews on the subject and discussing recent developments in the studies of the reaction mechanisms involved in their synthesis. 

The same tautomerism as that described for hydroxythiazoles is observed for mercap-tothiazoles (see Sections 4.19.2.3.5(i) and (ii)). 2-Mercaptothiazole exists predominantly in the A4-thiazoline-2-thione form (213) whereas 2-phenylthiazole-5-thiol exists in the thiol form (214). 

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