32 
OO 
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 
There is another very powerful argument in support of this view of the 
nature of the product. 
There is no doubt whatever that when it is heated bromide of acetyl is 
evolved (see below). Now, that is exactly what might be expected to occur 
with the aceto-bromide. Thus— 
‘Br 
(CH)PC — (0,H,),PO + CH,—COBr. 
0:0C—CH, 
Action of Heat on the product of action of Bromacetic Acid on 
Triethyl-Phosphine. 
In some of his earlier experiments on the product of action of bromacetic 
acid on triethyl-phosphine, the author had observed that when it is heated a 
crystalline body volatilises. 
This fact seemed to be one of importance, and he therefore determined to 
obtain this crystalline body in quantity, and to examine its properties. 
6 grms. of triethyl-phosphine were mixed in the usual way with 7 grms. of 
bromacetic acid, without diluting the latter with ether. When the action was 
at an end the product was at once submitted to the action of heat. It fused at 
a low temperature ; a few cubic centimetres of gas were evolved, and later a 
small quantity of a pungent fuming liquid distilled. This fuming liquid on re- 
distillation passed over before 100° C. It had the odour of bromide of acetyle, 
and its properties agreed with those of that body. On mixing it with water 
much heat was evolved, and on distilling the mixture (previously diluted with 
a considerable quantity of water) acetic acid passed over, and was identified 
by its silver salt. The residue contained hydrobromic acid. Moreover, on 
mixing some of the fuming liquid with fused acetate of potash, the odour of 
acetic anhydride was at once apparent. There can be no question therefore 
that it consisted mainly of bromide of acetyle. 
After the fuming liquid had passed over the thermometer rose rapidly, 
and a crystalline solid began to appear in the tube used as condenser. The 
distillation was stopped when nothing but a black carbonaceous mass remained 
in the distilling flask. The crystalline solid amounted to about 7 grms. in 
weight. It was melted out of the condensing tube, transferred to a distilling 
flask, and heated. It fused, and at first a little hydrobromic acid was evolved. 
The thermometer then rose to 303° C., and remained stationary,* whilst a 
colourless liquid passed over, solidifying to a white crystalline mass on cooling. 
At the end of the distillation the thermometer stood at 305° C., and about 5 
erms. of the crystalline product were obtained. 
* The condensing tube was changed when the temperature became constant. 
5 
