almecillin almecillin almecillin (inn), also known as penicillin o, is a penicillin that is similar in antibiotic action to penicillin g. it is obtained by isolation from penicillium chrysogenum. almecillinclinical dataother namespenicillinatc codenoneidentifierscas number87-09-2pubchem cid71365chemspider64462unii6246wh0s1ochebichebi:51207chemblchembl2105909comptox dashboard (epa)dtxsid50236034 chemical and physical dataformulac13h16n2o4s2molar mass328.40 g·mol−13d model (jsmol)interactive image smiles cc1(c)s2(nc(=o)cscc=c)c(=o)n21c(=o)o inchi inchi=1s/c13h18n2o4s2/c1-4-5-20-6-7(16)14-8-10(17)15-9(12(18)19)13(2,3)21-11(8)15/h4,8-9,11h,1,5-6h2,2-3h3,(h,14,16)(h,18,19)/t8-,9+,11-/m1/s1key:qulkgelypojslp-wcabbairsa-n