COUMARIN. 377 



soluble in water, easily in alcohol. Chromic acid oxi- 

 dizes it, forming benzoic acid. 



Coumarin, C 9 II 6 2 . Occurs in Tonka beans (the 

 fruit of Dipterix odoratd), partially in the form of 

 crystals ; in Melilotus officinalis, Asperula odorata, and 

 Anthoxanthum odoratum ; and can be extracted by 

 means of alcohol. After distilling off the greater part 

 of the alcohol, the residue is mixed with boiling water 

 and filtered, when the greater part of the coumarin 

 separates. It is also formed by the action of acetic 

 anhydride on the sodium compound of salicylic alde- 

 hyde (p. 323). Colorless, lustrous prisms, of a pleasant 

 aromatic odor; but slightly soluble in cold water, 

 more readily in hot water; fuses at 67, and boils 

 without decomposition at 291. When its aqueous 

 solution is treated with sodium-amalgam, it is con- 

 verted into coumaric and melilotic acids (p. 353); if on 

 the other hand, sodium-amalgam is allowed to act on its 

 alcoholic solution, the principal product formed is the 

 sodium salt of hydrocoumaric acid, C 18 H 18 6 , which crys- 

 tallizes in fine needles, difficultly soluble in cold water. 

 This acid, when heated, is resolved into water and its 

 anhydride, hydrocoumarin, C 18 H 14 O (needles ; fusing 

 point, 222). 



Coumarin dichloride, C 9 II 6 C1 2 2 (syrupy mass), and 

 Coumarin dibromide, C 9 H 6 Br 2 2 (colorless prisms), 

 are formed by the action of chlorine or bromine on 

 solutions of coumarin in chloroform or carbon bisul- 

 phide. When treated with alcoholic potassa, they yield 

 substitution-products of coumarin. The latter are also 

 formed by the action of phosphorus chloride or of bro- 

 mine on coumarin at a slightly elevated temperature.. 

 When the sodium compound of chlor- or bromsalicylic 

 aldehyde is treated with acetic anhydride, substitution- 

 products of coumarin are obtained that are isomeric 

 with those formed by direct action of the reagents. 



Coumarin is probably the anhydride of coumaric 

 32* 



