334 PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 
of the product obtained by the action of heat on bromacetic acid and triethyl- 
phosphine, but was rather softer and more buttery. 
Determination of the bromine it contained gave the following numbers :— 
(1) 07472 required 29'8cc decinormal AgNO, = 31:9 per cent. Bromine. 
(GORGE ee ee LPEIEE ; 
(3) 0°5665 ss, 230, ” » = 32°5 ” 
These numbers are somewhat higher than those obtained with the product 
of action of heat on bromacetic acid and triethyl-phosphine, but agree with those 
which Crarts and Sitva found in the product of action of hydrobromic acid on 
the phosphine oxide, before it had been re-distilled. 
Although the author feels convinced that all three products have a similar 
composition, he is unable at present to account for the slight differences 
observed in the amount of bromine which they contain. 
The experiment on the action of bromide of acetyl on oxide of triethyl-phos- 
phine may be considered as confirming the view that the author has already 
advanced concerning the nature of the product formed by the action of brom- 
acetic acid on triethyl-phosphine. 
The experiments just described show that the action of bromacetic action on 
triethyl-phosphine varies with the conditions in a very interesting and remark- 
able manner. 
The author thinks that he has proved that, at low temperatures, the two 
substances react so as to produce about equal quantities of hydrobromate of 
triethyl-phosphorus betaine and aceto-bromide of triethyl-phosphine, or a mix- 
ture of the latter with bromacetate of triethyl-phosphine. 
At intermediate temperatures very little of the hydrobromate is formed, and 
the product consists of the bromacetate and aceto-bromide ; whilst at higher 
temperatures the aceto-bromide is almost the sole product. 
Considering the very powerful affinity of phosphorus for bromine, the trans- 
formation of 
H 
(C#H)s=PC 
OOC—CH,Br 
into 
Br 
(CoH) =P 
OOC—OCH,, 
is readily intelligible, and there can be little doubt that bromacetate of triethyl- 
phosphine is a very unstable body. 
