monalazone monalazone monalazone, used as monalazone disodium (inn; the disodium salt) and sold under the brand names naclobenz-natrium, spergisin, and speton, is a vaginal disinfectant or antiseptic and spermicidal contraceptive. it is a sulfonylbenzoic acid derivative and is closely related structurally to halazone. the compound was synthesized in 1937. a vaginal tablet combination of 0.125 mg estradiol benzoate and 10 mg monalazone was previously marketed under the brand name malun 25. monalazoneclinical datatrade namesnaclobenz-natrium, spergisin, spetonother namesp-(chlorosulfamoyl)benzoic acidroutes ofadministrationvaginaldrug classdisinfectantatc codenoneidentifiers iupac name 4-(chlorosulfamoyl)benzoic acid cas number106145-03-3 61477-95-0 (disodium)pubchem cid68809chemspider62045unii2up9f49n8hchemblchembl2110958comptox dashboard (epa)dtxsid70147532 chemical and physical dataformulac7h6clno4smolar mass235.64 g·mol−13d model (jsmol)interactive image smiles c1=cc(=cc=c1c(=o)o)s(=o)(=o)ncl inchi inchi=1s/c7h6clno4s/c8-9-14(12,13)6-3-1-5(2-4-6)7(10)11/h1-4,9h,(h,10,11)key:wghswnhofpgmkj-uhfffaoysa-n