Cuprous mercaptide

Halothiophenes, which are not activated through the presence of —I—M-substituents, undergo substitution smoothly under more forcing conditions with copper salts in pyridine or quinoline. Hence 3-cyanothiophene and 5-methyl-2-cyanothiophene have been obtained from the corresponding bromo compounds. 2-Bromothiophene reacts readily with aliphatic cuprous mercaptides in quinoline at 200°C to give thioethers in high yields. The use of the copper-catalyzed Williamson synthesis of alkoxythiophenes from iodo- or bromo-thiophenes and alcoholate has been mentioned before. The reaction of 2-bromothiophene with acetanilide in nitrobenzene in... 

Aromatic chloro compounds cannot be used for reactions with aliphatic cuprous mercaptides. 

In early nutritional studies, cysteine was thought to be an essential amino acid. In 1937, Abraham White and E. F. Beach showed that cysteine could be removed from protein hydrolysates with cuprous mercaptide. Rats fed on such treated hydrolysates could grow, provided that sufficient methionine was supplied in the diet. 

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