13095-66-4 13095-73-3 4-03-00-00777 (Beilstein Handbook Reference) 4-Mercaptobutyric acid BRN 0773863 BUTYRIC ACID, 4-MERCAPTO- Butanoic acid, 4-mercapto- EINECS 236-013-5 GMBA gamma-Mercaptobutyric acid