ethinylestradiol benzoate ethinylestradiol benzoate ethinylestradiol benzoate, or 17α-ethynylestradiol 3-benzoate, is a synthetic estrogen and estrogen ester – specifically, the c3 benzoate ester of ethinylestradiol – which was first described in the late 1930s and was never marketed. ethinylestradiol benzoateclinical dataother names17α-ethynylestradiol 3-benzoatedrug classestrogen; estrogen esteridentifiers iupac name phenanthren-3-yl] benzoate pubchem cid13591267chemical and physical dataformulac27h28o3molar mass400.518 g·mol−13d model (jsmol)interactive image smiles c12cc3(1cc2(c#c)o)ccc4=c3c=cc(=c4)oc(=o)c5=cc=cc=c5 inchi inchi=1s/c27h28o3/c1-3-27(29)16-14-24-23-11-9-19-17-20(30-25(28)18-7-5-4-6-8-18)10-12-21(19)22(23)13-15-26(24,27)2/h1,4-8,10,12,17,22-24,29h,9,11,13-16h2,2h3/t22-,23-,24+,26+,27+/m1/s1key:pqpdfkstdgkonx-iujpgnivsa-n