"(a) Diacylated and polyacylated amines, such as N,N,N',N'-tetraacetylmethylenediamine, N,N,N',N'-tetracetylethylenediamine, N,N-diacetylaniline and N,N-diacetyl-p-toluidine; 1,3-diacylated hydantoins such as, for example," . . . .