Chemistry. — ''On the Saponi/icatioii of Fats". I. By Dr. J. P. Treub. 

 (Communicated by Prof. P. Zeeman). 



(Communicated in the meeting of December 21, 1916). 



Introduction. 



^ 1. The saponification of esters of glycerine has been first expe- 

 rimentally studied by Geitel. ') He determined the velocity of sapo- 

 nification of the three acetines in diluted acid solution, by titration 

 of the split off acetic acid, and came to the result, that the ratio 

 of the velocity constants of the reactions: triacetine ^ diacetine —> 

 monoacetine -» glycerine is as 3:2:1, from whicli follows that the 

 estergroups are all saponified with the same velocity, and that the 

 velocity of saponification of a certain estergroup is independent of 

 a neighbouring group being saponified or not. 



Abel ^) advanced against this that good constants are likewise 

 found when it is assumed that the saponification leads directly from 

 triglyceride to glycerine, and that therefore Geitel's measurements 

 of velocity do not prove anything. 



This is clear, as we arrive at the same equations of velocity in 

 the two different cases as Abel ^) has proved in another paper for 

 the general case of a reaction in n stages. 



However with his measurements of velocity Geitel has not proved 

 that the saponification of triacetine proceeds in stages, but only that 

 if it proceeds in stages the velocity constants of the three stages 

 must be in the ratio of 3:2: 1.^) This result on the contrary shows 

 the impossibility to decide whet[)er the process goes by stages or 

 not from measurements of the velocity of the splitting off of fatty 

 acid alone. ^) 



Geitel proved that the acid saponification of glycerine esters actually 

 takes place in stages by demonstrating that rancid fats contain more 



1) Z. f. pr. Ghem. (2) 55 429 (1897), 57 113 (1898). 



2) Ulzer u. Klimont, Chemie der Fette 244 (1906). 



3) Z. f. phys. Ghem. 56 558 (1906). 



*) J. Meyer has proved (Z. f. Electrochem. 13 485 (1907)), that this ratio 

 only holds in approximation. For 18° G. the following ratio seems to hold more 

 accurately: 3.10 : 2.00 : 1.14, for 25° G. : 8.06 : 2.00 : 1.25. 



5) Gf. also § 12. 



3* 



