546 



Chemistry. — ''The catalyse'. By Prof. J. Böeseken. (Coramuni- 

 cated by Prof. A. F. Holleman). 



(Communicated in the meeting of June 27, 1914). 



1. It appears to me that, a summary having been given from 

 various quarters on catalytic phenomena, the time has arrived to 

 sliow briefly how the development of my ideas on this subject has 

 advanced and how the insight thus gained has been supported by a 

 deduction of one of my students. 



I do this in the first place because in that historical account the 

 gradual elucidation of the phenomena is exposed, but also because 

 I imagine that a poini has now been reached where the co-operation 

 of many is necessary in order to assist in completing the edifice of 

 the catalysis. 



2. When working at my dissertation (1895 — 1897), when a large 

 number of fatty-ai'omatic ketones was prepared according to the 

 reaction of Friedel and Crafts, it struck me that when to a cooled 

 mixture of acid chloride and benzene finely powdered aluminium 

 chloride was added, this certainly dissolved rapidly, but that an 

 evolution of hydrogen chloride only took place slowlv on warming^). 



As aluminium chloride did not perceptibly dissolve in benzene, 

 I was then convinced that not the benzene but the acid chloride 

 might be the point of attack of the catalyst. 



This question was afterwards taken up by me and solved in so 

 far that the synthesis of the aromatic ketones could be divided into 

 two stages: (a) The catalyst combines with the acid chloride: (b) 

 this compound is attacked by the aromatic hydrocarbon (Rec. 19 

 19 (1900) 20 102 (1901). 



Although the course of the reaction was indicated therewith. I 

 was soon aware, however, that the catalytic action of aluminium 

 chloride remained in complete obscurity ""). 



In this I was corroborated by the observation that chloroform 

 and benzyl chloride suffered the reaction with benzene still far 

 better and more vigorously, whilst these substances did not combine 



1) Afterwards I modified the preparation by taking the AICI3 in excess and then 

 adding drop by drop the mixture of acid chloride and benzene, because the reaction 

 then proceeded very regularly. By the research of Olivier (Dissertation, Delft 1912) 

 it has been shown that the cause of this favourable result must be attributed to 

 the presence of free AIGI3 (see later). 



2) Perkier who had noticed this reaction course previously (These, Caen 1893) 

 was of opinion that this explained the catalytic action of aluminium chloride. 



