Detailed studies on the products of the alcoholysis of cyclohexylphosphonyl dichloride(Ⅰ) with 2-ethyl hexanol are described.It was found that the reaction proceeded incompletely when Ⅰ was reacted with calculated amount of alcohol in the presence of pyridine.Four fractions were obtained from the reaction product by distillation.The first fraction,as identified by gas chromatography,was unreacted 2-ethyl hexanol.The second fraction,as proved by hydrolysis to mono-2-ethylhexyl cydohexylphosphonate(Ⅳ) and by reaction with cyclohexylamine to form N-cyclohexyl 2-ethylhexyl cyclohexylphos-phonamidate(V),was shown to be 2-ethylhexyl cyclohexylphosphonochloridate(Ⅲ).The normal product of the alcoholysis reaction,di-2-ethylhexyl cyclohexylphosphonate,appeared in the third fraction only in 27.5% yield.The residue of the distillation was a neutral,yellow viscous liquid.On hydrolysis it yielded cyclohexylphosphonic acid(Ⅵ) and IV in the mole ratio of 1:14-19.