The O,O'-dialkyl phosphoryl cyanides(Ⅱ) were prepared in good yields by the reaction of sodium cyanide with dialkylphosphonates (Ⅰ) in the presence of carbon tetrachloride under appropriate conditions.The reaction mechanism was briefly discussed.In the above reaction,the order of the relative reactivities of dialkylphosphonates is as follows:
dimethyl > diethyl > di-n-propy > di-iso-butyl.
In the course of the preparation,side reactions were found,in which by-products such as tetraalkylpyrophosphates (Ⅲ,R=Me,Et,n-Pr,and i-Bu) were obtained.However,under suitable conditions.these side reactions can be almost completely suppressed.A detailed procedure is given.