1,1-Dimethyl-2-acetylhydrazine 6233-04-1 Acetic acid N',N'-dimethylhydrazide Acetic acid dimethyl hydrazide Acetic acid, 2,2-dimethylhydrazide EINECS 228-344-9 N',N'-Dimethylacetohydrazide N,N-Dimethylacetohydrazide NSC 42453