THE ROYAL SOCIETY OF CANADA 



EXPERIMENTAL. 



The Glycol and the Fat acids employed were Kahlbaum's purest 

 preparations and were tested before use. The Glycol boiled at 194 • 6°C. 

 and the acids after a preliminary recrystallization from warm 

 alcohol gave the following melting points : Palmitic melted at 62 • 5°C., 

 the Stearic at 69-2°C., The Oleic Acid fused at 14°C. The Margaric 

 acid was prepared by one of us^ by an adaptation of the Grignard 

 reaction and was especially purified, it melted at 59-7°C. 



Wiirtz^ synthesized the di-stearate by the action of ethylene brom- 

 ide on the silver salt of stearic acid. C2 H4 Br2+2Ag C is H35 02 = 

 2Ag Br+C2 H4 (C18 H35 02)2- Two of the esters were prepared by 

 this method viz., the di-stearate and the di-palmitate. 



The silver sa,lts employed were obtained in a crystalline form 

 from the corresponding ammonium soaps in alcoholic solution. The 

 ammonium salt of the fatty acid was made by nearly saturating an 

 alcoholic solution of the acid with dry ammonia. This solution was 

 then mixed with an equivalent proportion of an alcoholic solution of 

 silver nitrate, and the excess of ammonia distilled off with a little 

 of the alcohol. On cooling and standing the silver salt crystallized out 

 in fine feathery needles and was filtered off and washed. On account of 

 the comparatively low solubility of the ammonium salt as well as of the 

 silver nitrate, in alcohol near the room temperature, the solutions 

 were bulky and the preparations somewhat tedious. 



In preparing the ester, the dry silver salt in fine crystals was 

 added in small portions to an excess of ethylene bromide in a small 

 flask fitted with an air cooled return condenser, and heated in a paraffin 

 bath to about the boiling point of ethylene bromide 131°C. The re- 

 action proceeded slowly requiring 2-4 hours. The excess of ethylene 

 bromide was then distilled off and the ester separated from the silver 

 bromide and any remaining silver salt by extracting with boiling ether 

 and filtering the warm solution. The rapid filtering of a hot ether solu- 

 tion of fats, an operation of frequent occurrence in these preparations, 

 was found to be conveniently effected by the application of a small 

 air pressure over the filtering solution in a warm Buchner filter, by the 

 use of an inverted glass funnel with a rubber contact and the stem 

 connected to a foot bellows. The ether was then distilled off and the 

 residue crystallized from hot, nearly anhydrous alcohol. 



The solubility in alcohol of each of these esters decreases rapidly as 

 the temperature falls and with increasing water content in the alcohol ; 

 the di-esters readily forming two liquid layers with 60-70% alcohol 



1 Ruttan, Trans. International Chem. Congress, 1912, vol. XXV, p. 431. 



2 Wurtz, Ann. de chem. et phys. (3) 55,436. 



