012 PROF. LETTS AND MR R. F. BLAKE ON 



Analysis. (The salt lost 7*43 per cent, on drying it at 110° C.) 

 0-10273 gave 0"0304 CuO = 00242 Cu = 25"26 per cent. 



Calculated for 



Obtained. C 7 H 7 P0 3 Cu (C 7 H 7 HP0 2 ) 2 Cu 



Copper, . . . 2526 27-03 1700 



The salt was probably impure benzyl phosphinate of copper, and not phosphinite at all. 

 The mother-liquors which had been filtered from it rapidly decomposed and a yellow to 

 red precipitate separated, having the appearance of cuprous oxide. On warming the 

 wash waters, especially if they contain excess of acetate of copper, the light green salt 

 is precipitated, but redissolves as the solution cools. It appears, therefore, that benzyl 

 phosphinite of copper, if it exists at all, is a very unstable substance, and rapidly oxidises 

 to phosphinate. The behaviour of a phosphinite with a copper salt affords an excellent 

 test for the acid. 



Action of Heat on Benzyl Phosphinous Acid. — A quantity of the acid was heated 

 in a small retort. It rapidly decomposed, and a liquid distilled, having the characteristic 

 odour of the primary phosphine, smoking on coming in contact with the air, and giving 

 a crystalline compound with hydriodic acid, which volatilised in that gas in the charac- 

 teristic manner of the phosphine hydrioclate. The reaction probably proceeds according 



to the equation — 



3(C 7 H 7 )H 2 P0 2 = 2(C 7 H 7 )H 2 P0 3 + (C 7 H 7 )H 2 P , 



giving the primary phosphine and benzyl phosphinic acid, and is analogous to the decom- 

 position which phenyl phosphinous acid suffers when heated.* 



(2) Benzyl Phosphinic Acid, (C 7 H 7 )H 2 P0 3 . 



This acid is produced along with the benzyl phosphinous acid in the three reactions we 

 have mentioned above, but it is only formed in very small quantity during the oxidation of 

 the primary phosphine, benzyl phosphinous acid being, as we have mentioned, by far the 

 chief product. A similar remark applies to the reaction occurring between oxide of zinc, 

 benzyl chloride, and phosphonium iodide, only very small quantities of the benzyl phos- 

 phinic acid being found among the products. The only satisfactory method for obtain- 

 ing it is by the third process we have mentioned, i.e., the action of benzyl alcohol on a 

 mixture of phosphorus and phosphorus iodide, when it is produced in large quantities, and 

 is easily separated from the other products of the reaction. 



The following are the details of the process : — 5 5 '5 grms. of phosphorus are dissolved 

 in an equal weight of bisulphide of carbon in a flask about 1 litre in capacity, and 9 4 '5 

 grms. of iodine are gradually added. The bisulphide is then distilled off and the last 

 traces removed by a current of dry carbonic anhydride. An upright condenser is now 

 fitted to the flask (which must be filled with dry carbonic anhydride) and 159 grms. 

 of benzyl alcohol cautiously added through the condenser from a tap funnel. As soon as 



* Michaelis and Ananoff, Ber., vii. 1688 ; and Kohler and Michaelis, Ber., x. 807. 



