Chemistry. — '-The Light O.rldation of Alcohol (III). The Phoio- 

 Catalytic Influence of some Series vf Ketones on the light 

 Oxidation of Ethyl Alcohol". By W. D. Cohen. (Communicated 

 by Prof. J. Böeseken). 



(GommuDicated at the meeting of May 26, 1923). 



Introduction. A first comnuiiiioation on this subject appeared 

 in these proceedings') already several years ago; a continuation of 

 this was published by Bökskken '). In this paper the theoretical 

 grounds on which these researches are f'oumied, are set fortli in 

 extenso'), and we may, tiierefore, refer to this treatise for a study 

 of them. 



It was now my purpose to examine what relation exists between 

 the configuration of a ketone and its plioto-catalytic influence on 

 the oxidation of a definite alcohol, and for this reason I studied the 

 infiuence of some series of ketones on the velocity of oxidation of 

 ethyl alcohol, to be able, if possible to arrive at a conclusion with 

 regard to the constitutive requirements which a ketone must satisfy 

 to be able to act as a photo-catalyst under the circumstances specified 

 later, which at the same time establishes its photo-chemical altackaliilily. 

 This question has, indeed, already been mentioned more than once 

 before'), but the comparatively small regularity in the observed 

 phenomena rendered an extension of the research in this direction 

 very desirable. 



The light-thermostat. In the reaction : 



Light-)- Ketone -|- Alcohol -|- Oxygen = Ketone -|- Aldehyde -|- Watei 



a certain quantity of oxygen disappears, and the rapidity with which 

 the oxygen is absorbed, is under for the rest fixed circumstances, 

 a measure for the photo-catalytic activity of the examined ketone. 

 The light thermostat (fig. 1) consists of a copper trough, provided 

 with two windows placed opposite each other in the longitudinal 

 walls, which make a continual observation of the reaction vessel 



1) Böeseken and Cohen, These Froc. XVlIi, p. 1640. 



«) Böeseken, Ree. 40, 433 (1921). 



') Ibid, 437. 



*) Cohen, Rec. 39. 258 (1920). Chem. Weekblad 13, 902 (1916). 



29 

 Proceedings Royal Acad. Amsterdam. Vol. XXVI. 



