378 COUMARIC ACID, ETC. 



acid, and constituted according to the formula 



*? 

 CH:CH. 



When sodium-salicylic aldehyde is heated with 

 butyric and valeric anhydrides, compounds homologous 

 with coumarin are formed : butyric coumarin, C n H 10 2 

 (needles; fusing point, 70-71; boiling point, 296- 

 297) and valeric coumarin, C 12 H 12 2 (long prisms; 

 fusing point, 54 ; boiling point, 301). 



Coumaric acid, C 9 H 8 3 = C 6 H 4 j cH-CH.CO.OH. 



Is contained in Melilotus offidnalis and in the leaves of 

 Faham. Is formed from coumarin by boiling with very 

 concentrated potassa-ley. Colorless, lustrous prisms; 

 easily soluble in hot water and in alcohol ; fuses at 

 195 ; not volatile without decomposition. Fused with 

 potassa, it yields potassium salicylate and acetate. 

 The solutions of its alkaline salts are markedly 

 fluorescent. 



Paracoumaric acid, C 9 H 8 3 = 



{OTT 

 CH-CHCOOH ^ s P r d uce( l ^7 boiling an 



aqueous solution of aloes, to which has been added 

 sulphuric acid; and, after filtering, it can be extracted 

 from the solution by means of ether. Colorless, lus- 

 trous, brittle needles. But slightly soluble in cold water, 

 easily soluble in hot water and in alcohol; fuses at 179- 

 180. Fused with potassium hydroxide, it is converted 

 into paraoxybenzoie acid. It combines with nascent 

 hydrogen, forming hydroparacoumaric acid (p. 354). 

 When boiled with fuming nitric acid, it yields picric 

 acid, 



Caffeic acid, C 9 IFO = C 8 H 5 a Is formed, 



together with sugar, by boiling caffetannic acid (or 

 extract of coffee) with potassa-ley ; and separates from 



