Thioamides

General formula of thioamides. The radicals R ¹ to R ³ are hydrogen atoms or organyl radicals ( alkyl radicals, aryl radicals, alkylaryl radicals, etc.). The thioamide group is marked in blue .

Thioamides (also thioamides or thionamides) are derived from amides (more precisely: carboxamides ) whose carbonyl oxygen atom has been replaced by a sulfur atom. The thioamides are mesomeric stabilized .

synthesis

The most common method for the synthesis of thioamides is based on the addition of hydrogen sulfide to nitriles :

The synthesis also succeeds in the low pressure process in the presence of triethylamine . According to this method, however, only thioamides that have two hydrogen atoms on the nitrogen atom are available. The synthesis of more highly substituted thioamides starts with amides and reacts them with Lawesson's reagent or phosphorus pentasulfide in an inert solvent:

Reactivity

The most important preparative reaction of the thioamides consists in the synthesis of numerous heterocycles , e.g. B. of thiazoles .

Representative

Inhibitors of hormone production in the thyroid gland:

• Thiamazole
• Carbimazole
• Propylthiouracil

Herbicides:

• Chlorothiamide

Individual evidence

1. ↑ ^{a b c} Alfons Schöberl and Annemarie Wagner in Houben-Weyl Methods of Organic Chemistry , edited by Eugen Müller, Otto Bayer, Hans Meerweis and Karl Ziegler, Volume 9, sulfur, selenium and tellurium compounds , Thieme Verlag, Stuttgart, 1955 , there pp. 762-771.
2. ↑ Small synthesis corner. Accessed July 31, 2018 (German).