(R,S)-5-Ethyl-5-(1-ethylbutyl)barbitursaeure 5-Ethyl-5-(1-ethylbutyl)barbituric acid 76-23-3 Butysedol EINECS 200-946-6 IL 991 Tetrabarbital Tetrabarbital [DCF:INN] Tetrabarbitalum [INN-Latin]