876 



acids, it seemed not impossible to me that there occurred a tetra- 

 methylene ring in the product of illumination of cumarin. If this were 

 the case, however, the substance would have to yield not a mono- 

 basic, but a di-basic acid on treatment with alkalis, and the product 

 of illumination of cumarin would not be identical with the hjdrodi- 

 cumarin of Fittig and Dvson. 



The possibility of this was not excluded, as Ciamician and Silber 

 give 262° as melting point of their product, Fittig and Dyson 

 having found 256° for the hydrodicumarin. 



I have prepared the product of illumination of cumarin by 

 illumination of an aqueous solution that was not covered by glass, 

 while the hydro-diciimarin was made according to the directions 

 of Fittig and Dyson. The melting-points of the substances agreed 

 with those given by the investigators. A mixture of the two substances 

 melted, however, already at 225°. This proves that the substances 

 differ. 



This may be confiimed by what follows. The product of illumi- 

 nation of cumarin crystallizes from chloroform in microscopic plates, 

 which often look like rectangles ; hydrodicumarin separates out of 

 the solvent mentioned in microscopic needles joined to sheaves. 



The product of illumination of cumarin dissolves in sodium hydroxide 

 of about 80 °/o in a few minutes at the ordinary temperature. 

 Through hydrochloric acid it is precipitated from this solution 

 unchanged. When the alcalic solution is boiled for an hour with an 

 ascending still-head, then on addition of hydrochloric acid to the 

 cooled solution a di-basic acid se[)arates, which first crystallizes in 

 fine microscopic needles, which, however, are soon transformed to 

 thicker needles that join to stars and crosses. The acid melts at 

 245°; the melt smells strongly of cumarin, and easily dissolves in 

 alcohol at the ordinary temperature. Also in a sodium-carbonate 

 solution the melt is readily soluble. 



As has already been communicated by Fittig and Dyson, the 

 hydrodicumarin gave after being heated for a long time with alkalis, 

 a mono-basic acid, the hydrodicumaric acid, which when heated to 

 the melting point, was again converted to hydrodicumarin, which is 

 insoluble in alcohol, and also in a sodium-carbonate solution. 



It appears, therefore, clearly from this that the product of illumi- 

 nation of cumarin is no hydrodicumarin. 



I hope shortly to give a fuller discussion of the structure of the 

 product of illumination of cumarin. 



Buitenzorg, July 1917. 



