4-04-00-03524 (Beilstein Handbook Reference) 7305-61-5 BRN 1749049 Ethylphosphonic acid ethyl ester O-ETHYL ETHYLPHOSPHONATE O-Ethyl ethanephosphonic acid O-Ethyl hydrogen ethylphosphonate Phosphonic acid, ethyl-, ethyl ester Phosphonic acid, ethyl-, monoethyl ester