The structures of the hydrogen halide salts of succinonitrile and related compounds

The constitutions of the hydrogen halide salts of succinonitrile are shown to be 2-amino-5,5-dihalo-1-pyrrolinium halides (II) and are thus the next lower homologs of the corresponding salts of glutaronitrile.¹ On the other hand the homologous 2,3-diphenyl-succinonitrile when treated with hydrogen bromide leads to 5-amino-2-bromo-3,4-diphenyl-3H-pyrrole hydrobromide (IX) which is tautomerically different from the analogous salt obtained previously from 2,5-diphenylglutaronitrile. The hydrolysis of IX has been examined and the products completely characterized. 2,2,3,3-Tetramethylsuccinonitrile in ether affords 5-imino-3,3,4,4-tetramethyl-2-pyrrolidone hydrobromide when treated with anhydrous hydrogen bromide whereas 1,1′-dicyano-1,1′-bicyclohexyl is unreactive towards this gas, in aprotic solvents.