Chemistry. — "Action of Solai^ Light on Cumarin". By A. W. 

 K. DE Jong. (Communicated by Prof. P. van Romburgh). 



(Communicated in the meeting of Nov. 24, 1917). 



GiACOMO CiAMiciAN and Silber ') have communicated that cumarin 

 in solid state and also in aqueous and alcoholic solution changes 

 by solar light into hydrodicumarin, which substance was synthetically 

 obtained by Fittig and Dyson "), starting from salicylaldehyde and 

 succinic acid. According to the last investigators the formula of the 

 hydrodicumarin was the following: 



- CO CO — \ 

 C.H^ I I >C\H, 



^CH = C — CH — CH/ 



Ciamician and Silber write, that wiien we do not wish to assume 

 a tetramethylene ring in the polymerised cumarin, the following 

 formula is to be preferred in their opinion to that given by Fittig 

 and Dyson : 



— CO CO — V 

 C.H,< 1 I )>C,H, 



^CH, — C = C — CH/ 



This formula, however, does not take the properties of hydrodi- 

 cumarin into account. According to Fittig and Dyson this substance 

 is namely converted into hydrodicumaric acid, a mono-basic acid, 

 by long boiling with "ziemlich concentrirten freien Alkaliën". 



The cumarin ring is diflicult to open by boiling with alkalis, so that 

 this property of the hydrodicumarin is in perfect agreement with 

 the formula given to it by the two investigators. A substance that 

 should possess the formula given to hydrodicumarin by Ciamician 

 and Silber, should easily give a di-basic acid on being heated with 

 alkalis, as there are here no cumarin rings, but hydro-cumarin rings 

 present, which are easily opened when the substance is heated 

 with alkalis. 



In connection with the possible stucture of the truxillic acids, two 

 of which arise by the action of light from the normai cinnamic 



1) Ber. 35, 4130 (1902); Ber. 47, 642 (1914). 



2) Ann. 255, 280 (1889). 



