Drushel and Hill — Esters of Halogen Substituted Acids. 77 



latter by the former. In the same way we determined tlie 

 coetficient for N/20 hydrochloric acid for the temperature 

 change from 25° to 35° and found it to be 2-0. For N/20 

 hydrobromic acid it has been found to be 1'7. For the range 

 25° to 40° hydrochloric has a coefficient of 3*0. These coeffici- 

 ents have been used in calculating some of the results for 

 Table I. 



On inspection of this table it will be seen that the rate of 

 hydrolysis is lowered to a. marked extent by the introduction of 

 one atom of halogen, the chlorine substituted esters having the 

 lowest rate. The contents of the acetates, chloracetates and 

 bromacetates are to each other as 33 : 21 : 25. 



Apparently the most favorable conditions for hydrolysis 

 exist when both base and acid are weak.* In the hydrolysis 

 bf the acetic esters we have such conditions, for the alcohols are 

 weak bases and acetic acid is a weak acid, giving a relatively 

 large constant. Chloracetic acid is a stronger acid and the 

 rate of hydrolysis is correspondingly lower. Bromacetic acid 

 is not so strong as chloracetic but much stronger than acetic 

 acidf and its esters are found to have constants slightly larger 

 than those of the chloracetic esters but smaller than those of 

 the acetic esters. The nature of the alcohol seems to have little 

 effect on the rate of hydrolysis. 



Table I. 



Methyl Acetate Methyl Chloracetate 

 lO'^xK 10= xK 



25° and -OSN HCl 25° and -OGN HCl 



Methyl Bromacetate 



WxK 



25° and -OSN HBr 



I II 



33-8 



25-8 



29-5 



37-0 



33-5 



25-2 



33-5 



27-0 



33-2 





350 





Mean 33-0 



Mean 26-3 



26-4 

 26-6 

 26-2 

 25-5 



26-0 



-Mean- 



24-7 

 25-3 

 24-6 



24-8 



Ethyl Acetate 

 I II Ethyl Chloracetate 



25° and 40° and 25° and 



•05N HCl •123N HCl •094N HCl 



Ethyl Bromacetate 

 25° and •05N HBr 

 I II 



30-1 



248- 



39-8 



24-4 23-6 



28-0 



324- 



35-0 



231 24-6 



30-3 



272- 



36-2 



23-8 23-3 



31-5 



229- 



40-8 





29-3 





38-9 





29-8— Mean- 



-243- 



Mean 38-9 



23-8— Meaa— 23-8 



*Nemst, Theoretical Chemistry, p. 521. 



f By inversion of cane sugar Ostwald found acetic acid has value of '004 

 and chloracetic acid '048 that of hydrochloric acid. From determinations 

 of affinity constants he found that chloracetic and bromacetic acids have 

 values near to each other, viz., 0"155 and 0"138. See Jour, pi-akt. Chem. (2), 

 xxix, 385, 1884. Also Zeitschr. phys. Chem., iii, 418. 



