325 



TABLE I. Without coal. 



TABLE II. mth coal. 



expected, we Hieii have lound and accelleratioi» of the reaction. We 

 repeated these experiments in a 'COj-atmosphere and in the daik 

 room to avoid complications. The lesult was almost the same: 

 without coal we found k = 0.000123 and when coal was added 

 k = 0.000149. 



The place of the polar groups in dibromo-propionic acid is however 

 not symmetric; the possibility remains that the COOH-group exerts 

 a more vigorous orientating influence than the Br groups and con- 

 sequently the latter will not be in a most favourable condition. A 

 better result could be expectod therefore in the case of the reaction 

 of dibromo-succinic acid and KJ. A comparison between the 

 formulae 



HC— CH— COH en HOC— CH— CH— COH 

 Br Br Ö Ö Br Br Ö 



will elucidate this immediately. Moreover, the stereochemical confi- 

 guration suggests a still better arrangement in the case of the 

 mesoform than in that of the racemic. In the tables III and IV we 

 give the results obtained with the racemic, in the tables V and VI 



TABLE III. 

 Racem ic-acid without coal. 



TABLE IV. 

 Racem ic-acid with coal. 



k mean 0.000115 

 Proceedings Royal Acad. Amsterdam. Vol. XXV. 



k mean 0.000408 

 21 



