cefonicid cefonicid cefonicide (or cefonicid) is a cephalosporin antibiotic. cefonicidclinical dataahfs/drugs.commicromedex detailed consumer informationmedlineplusa601206atc codej01dc06 (who) identifiers iupac name (6r,7r)-7--8-oxo-3--5-thia-1-azabicyclooct-2-ene-2-carboxylic acid cas number61270-58-4pubchem cid43594chemspider39734 yunii6532b86wfgkeggd07644 ychebichebi:3491 ychemblchembl1601 ycomptox dashboard (epa)dtxsid7022758 chemical and physical dataformulac18h18n6o8s3molar mass542.56 g·mol−13d model (jsmol)interactive image smiles o=c2n1/c(=c(\cs12nc(=o)(o)c3ccccc3)csc4nnnn4cs(=o)(=o)o)c(=o)o inchi inchi=1s/c18h18n6o8s3/c25-13(9-4-2-1-3-5-9)14(26)19-11-15(27)24-12(17(28)29)10(6-33-16(11)24)7-34-18-20-21-22-23(18)8-35(30,31)32/h1-5,11,13,16,25h,6-8h2,(h,19,26)(h,28,29)(h,30,31,32)/t11-,13-,16-/m1/s1 ykey:dyaiahuqipbdip-axapsjfssa-n y (verify) it has a density of 1.92g/cm3. synthesis injectable semi-synthetic cephalosporin antibiotic related to cefamandole, q.v. cefonicid synthesis: cefonicid is synthesized conveniently by nucleophilic displacement of the 3-acetoxy moiety of 1 with the appropriately substituted tetrazole thiole 2. the mandelic acid amide c-7 side chain is reminiscent of cefamandole.