296 M. Wurtz on Propyle-glycol. 



by repeated rectification ; the fraction boiling between 140° and 

 145° C. is pure bromide of propylene. 



320 grms. of acetate of silver were treated with 192 grms. 

 bromide of propylene, as much glacial acetic acid added as made 

 the whole of a pasty consistence, and the mixture heated for four 

 days in the water- bath. ^Ether was then added, the mixture 

 filtered, and the liquid fractionally distilled, — that portion boil- 

 ing between 180° — 190° being acetate of propyle-glycol. Its 



Q6JJ6 -| 



composition is C* H'^ 0^-= ,^^ ^13 qons rO'* > ai^'l its formation 

 may be thus expressed : — 



C6 H« Br^ + 2^' ^^^'1 0^= (g fp 02)2} 0^ + 2Ag Br. 



Bromide of Acetate of silver. Acetate of propj le- Bromide of 

 propylene. glycol. silver. 



Acetate of propyle-glycol is a colourless neutral liquid, insoluble 

 in water, and with an odour somewhat resembling acetic acid. 

 It boils at 186° C, and has the specific gravity 1*109. 



Propyle-glycol was obtained by treating pure acetate with hy- 

 drate of potash and distilling the mixture. This distillate was 

 rendered slightly alkaline with a small quantity of potash, di- 

 stilled again, that portion collected which boiled above 180°, 

 and this again rectified. The reaction is thus expressed : — 



Acetate of propyle- Propyle-glycol. Acetate of potash, 



glycol. 



"When pure it is a colourless oily liquid with a sweetish taste. 

 It boils at 188° C, thus exhibiting the strange anomaly that its 

 boiling-point is lower than that of its lower homologue, glycol. 

 When treated with even very dilute nitric acid it is decomposed, 

 hydrogen and carbon being eliminated, and glycolic acid, the 

 oxidation product of glycol, being obtained. But by inducing a 

 slow oxidation by means of platinum-black, a different result is 

 obtained. On the flat bottom of a flask, 70 grms. of a mixture of 

 platinum-black and spongy platinum wore placed, and after filling 

 the flask with carbonic acid, 6 grms. of propyle-glycol dissolved 

 in 10 grms. water were added. The flask was left unclosed for 

 eight days, so that tlie air could gradually penetrate. At the expi- 

 ration of that time the liquid had become strongly acid, and after 

 purification it was found to consist of lactic acid containing a 

 small quantity of glycolic acid. Hence, by the slow oxidation of 

 propyle-glycol, lactic acid is formed : 



C« W » + " = H2 02 -f C^ 116 06. 

 Propyle-glycol. Lactic acid. 



And il is worthy of notice, that the starting-point for the pre- 



