BENZYL PHOSPHINES AND THEIR DERIVATIVES. 605 



As the percentages both of calcium and barium in the respective salts analysed 

 indicated that they did not consist of the pure phosphinites, but contained some hypo- 

 phosphite, it was determined to obtain the zinc salt, which is deposited in a very character- 

 istic way on boiling a weak solution of the phosphinous acid with acetate of zinc. 

 Accordingly, the remainder of the barium salt was exactly decomposed with sulphuric 

 acid, the solution filtered from the precipitated sulphate of barium and diluted. Acetate 

 of zinc was then added (to the boiling solution), when it became turbid, and deposited a 

 small quantity of a resinous salt. This was filtered off and excess of acetate of zinc, 

 added, when a salt was precipitated (when the solution had been boiled for some time) in 

 the characteristic form of the phosphinite, viz., minute droplets, with crystalline points 

 projecting in all directions. A determination of zinc proved it to be the pure 

 substance. 



Analysis. 



0-3044 gave 00670 ZnO=00537 Zn=l7-64 per cent. 



Obtained. Calculated for { (C 7 H 7 )P0 2 H } 2 Zn 



Zinc 17-64 17-33 



The results of these experiments show that in the reaction occurring between benzyl 

 alcohol and the phosphorus mixture all the possible products of the oxidation of the 

 three benzyl phosphines are produced, while in addition, in the experiment last described, 

 iodide of tetrabenzyl phosphonium was also formed. In this experiment the conditions 

 were slightly different from those of the preceding, for an excess of the phosphorus mixture 

 was employed, but whether this influenced the course of the reaction or not we have not 

 had the opportunity to decide. 



When we come to inquire into the mechanism (so to speak) of the reaction by which 

 these different substances are formed, our attention is first arrested by the fact that 

 two series of phosphorised derivatives are produced by the action of benzyl alcohol 

 on the mixture of phosphorus and its iodide. One of these (excluding toluol) is 

 represented by a solitary substance, viz., iodide of tetrabenzyl phosphonium, which 

 contains less oxygen than the alcohol. The other includes all the possible products of 

 the oxidation of benzyl phosphines, and, with the exception of oxide of tribenzyl phos- 

 phine, contains more oxygen than benzyl alcohol. To a certain extent, therefore, the 

 reaction is analogous to that which occurs between water and the phosphorus mixture, in 

 which phosphonium iodide is a product of reduction, while phosphorous and phos- 

 phoric acids are products of oxidation. To account for this double set of 

 actions in the case of benzyl alcohol {i.e., reduction and oxidation) is not 

 difficult. The primary reducing agents are phosphorus and its iodide, while in the later 

 stages of the reaction there is hydriodic acid also. As to the oxidising agent, iodine is 

 visibly liberated in the first phases of the reaction, and probably water also, so that we 

 think it probable that it is by their interaction that some of the oxidised products are 



