378 DriLshel and Bancroft — Esters Derived from the 



from the esters, or the halogen substituted alcohols resulting 

 from the hydrolysis of the esters, titratious were made with 

 decinormal silver nitrate at the time when the equilibrium 

 was reached in the titration of the acid with decinormal sodium 

 hydroxide. 



At 25° and 35° there was no splitting out of halogen in the 

 case of the yS-chlor-ethyl acetate, and none from the y8-brom- 

 ester at 25°. At 35° and 45°, however, the /S-brom-ethyl ace- 

 tate was found to decompose slightly in this way, and at 45° a 

 slight decomposition was indicated in the case of the /S-chlor- 

 ethyl acetate, whicli was so small as to be negligible. The 

 necessary correction for the formation of halogen acid was 

 applied to the titrations made at 35° and 45° in the hydrolysis 

 of the /3-brom-ethyl acetate, where as much as 4 per cent to 

 4*5 per cent of the halogen was found to be set free as halogen 

 acid. 



From the titrations made as described above the velocity- 

 constants recorded in Table I were calculated by using the 

 titration formula for monomolecular reactions : 



K = ^ 



f [log (T. - T.) - log (T. - T„)]^ 



where Tq is the initial titration, T^ the final titration, and Tn 

 an intermediate titration all expressed in cubic centimeters of 

 decinormal sodium hydroxide, and t represents the time inter- 

 val in minutes between the initial titration To and that repre- 

 sented by Tn. 



On referring to Table 11 it is seen that the substitution of 

 chlorine, of hydroxyl, and of ethoxyl groups in the beta posi- 

 tion produces practically the same retardation of the rate of 

 hydrolysis in each case. The substitution of bromine in the 

 beta position produces a retardation of the hydrolysis which is 

 considerably less than that produced by the chlorine substitu- 

 tion. The ethoxyl group produces a slightly greater retarda- 

 tion than the methoxyl group. 



The temperature coethcients are found to vary from 2-2 to 

 2'5 for an increase of ten degrees. The substitution of bro- 

 mine in the beta position has a lowering eifect upon the tem- 

 perature coefficient. In the case of other esters of this series 

 the coefficients were found to be practically constant, having 

 the values of 2*5 for the range from 25°-35° and 2*3 to 2*4 for 

 the increase from 35°-45°. 



Summary. 



1. The /3-hydroxy-etlnl acetate may be prepared by reflux- 

 ing equimolecular quantities of ethylene glycol and glacial 

 acetic acid for eight hours over twice the theoretical quantity 

 of anhydrous copper sulphate. 



2. By heating equimolecular quantities of ethylene dibro- 

 mide and freshly fused potassium acetate on a water bath for 



