10.22376/ijpbs.2019.10.1.p1-12 Volume 1 Issue 1 2010 (January - March) Novel O-ethyl O-heteroaryl 2-chloroethyl phosphonates have been prepared by condensing 2-chloroethyl phosphonyl dichloride by the sequential addition of ethanol and –OH and –SH carrying heteroaryls. Attempts of the above reaction with –NH carrying heteroaryl (benzimidazole) furnished a different product than the expected one by different reaction path. Atulya Kumar Panda 1-Methyl benzimidazole, 3-Hydroxy 5-phenyl isoxazole, O-Methyl O-(5-phenyl isoxazol-3-yl) 2-chloroethyl phosphonate, O-Ethyl O-(5-phenyl isoxazol-3-yl) 2-chloroethyl phosphonate, O-Ethyl O-(quinolin-8-yl) 2-chloroethyl phosphonate, O-Ethyl S-(benzimidazol-2-yl) 2-chloroethyl phosphonate, O-Ethyl S-(benzothiazol-2-yl) 2-chloroethyl phosphonate -