Section III, 1918 [13] Trans. R.S.C. 



Stearic and Palmitic Esters of the Isomeric Propylene Glycols. 

 By L. Isabel Howe. 

 Presented by Dr. R. F. Ruttan. 



(Read May Meeting, 1918.) 



Historical. — The fat acid esters of ethylene glycol were prepared 

 by Ruttan and Roebuck^ in 1915, and their physical and chemical 

 constants were described. It was found that they could best be 

 prepared by the direct union of the acid with the glycol at a com- 

 paratively high temperature, with constant stirring, and that the 

 separation of the mono and di-derivatives could only be effected by 

 prolonged fractional crystallization. 



Previous to this only one glycol ester had been prepared namely, 

 the distearate of ethylene glycol in 1895 by Wiirtz. He used the 

 silver salt of the acid with ethylene bromide, but this gave only the 

 di-compound, and although many attempts were made by Ruttan 

 and Roebuck it was found quite impossible to obtain any trace of 

 the mono derivative. To prepare the silver salt of the fat acid, a 

 solution of the acid in alcohol was saturated with dry ammonia, and 

 an equivalent proportion of an alcoholic solution of silver nitrate 

 added. After the ammonia and some of the alcohol had been distilled, 

 the salt precipitated out in fine needles. However, this process is very 

 tedious and has now been replaced by the direct esterification 

 method. 



In this paper are described the preparation and properties of the 

 fat acid esters of the two isomeric propylene glycols, namely, 1. 2. 

 di hydroxy propane, and 1. 3. di hydroxy propane or trimethylene 

 glycol, and their chemistry compared with that of the ethylene glycol 

 esters. 



Experimental. — Only the very purest materials were employed 

 in the following experiments, and these were carefully tested before 

 use. The charge, consisting of the glycol with the fat acid, was 

 esterified at a constant temperature for several hours in the electric 

 oven, the mixture being constantly agitated by a platinum stirrer, 

 which was run by a small electric motor. At the comparatively high 

 temperature employed the water formed during the reaction was 

 driven off. A hard cake of fat was obtained, which was melted 



^Trans. Royal Society of Canada — 1915 — Vol. IX. Series 3. 



