thiobarbital thiobarbital thiobarbital is a drug which is a barbiturate derivative. it is the thiobarbiturate analogue of barbital. thiobarbitalidentifiers iupac name 5,5-diethyl-2-thioxodihydropyrimidine-4,6(1h,5h)-dione cas number77-32-7 npubchem cid667509chemspider580885 yuniih4fnf051kscomptox dashboard (epa)dtxsid40227810 echa infocard100.000.929 chemical and physical dataformulac8h12n2o2smolar mass200.259 g·mol−13d model (jsmol)interactive image smiles o=c1nc(=s)nc(=o)c1(cc)cc inchi inchi=1s/c8h12n2o2s/c1-3-8(4-2)5(11)9-7(13)10-6(8)12/h3-4h2,1-2h3,(h2,9,10,11,12,13) ykey:qgvnjrroslygkf-uhfffaoysa-n y ny (what is this?) (verify) synthesis thiobarbital synthesis: it is of note that although the drug can be prepared by the above route (cf e.g. thialbarbital), reaction of barbital with phosphorus pentasulfide constitutes an alternative route to thiobarbital.