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COUMARIN, C9H602
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See also:COUMARIN, C9H602 , a substance which occurs naturally in sweet woodruff (Asperula odorata), in the tonka See also:bean and in yellow melilot (Melilotus off cinalis). It can be obtained from the tonka bean by extraction with See also:alcohol. It is prepared artificially by See also:heating aceto-ortho-coumaric See also:acid (which is formed from See also:sodium salicyl aldehyde) or from the See also:action of acetic anhydride and sodium acetate on salicyl aldehyde (See also:Sir W. H. See also:Perkin, Berichte, 1875, 8, p. 1599). It can also be prepared by heating a mixture of phenol and malic acid with sulphuric acid, or by passing See also:bromine vapour at ro7° C. over the anhydride of melilotic acid. It forms rhombic crystals (from See also:ether) melting at 67°'C. and boiling at 290° C., which are readily soluble in alcohol, and moderately soluble in hot See also:water. It is applied in See also:perfumery for the preparation of the Asperula essence. On boiling with concentrated See also:caustic potash it yields the See also:potassium See also:salt of coumaric acid, whilst when fused with potash it is completely decomposed into salicylic and acetic acids. Sodium See also:amalgam reduces it, in aqueous See also:solution, to melilotic acid. It forms addition products with bromine and hydrobromic acid. By the' action of See also:phosphorus pentasulphide it is converted into thiocoumarin, which melts at See also:roe C.; and in alcoholic solution, on the addition of See also:hydroxylamine hydrochloride and soda, it yields coumarin oxime. Ortho-coumaric acid (o-oxycinnamic acid) is obtained from coumarin as shown above, or by boiling coumarin for some See also:time with sodium ethylate. It melts at 208° C. and is easily soluble in hot water and in alcohol. It cannot be converted into coumarin by heating alone, but it is readily transformed on heating with acetic anhydride or acetyl chloride. By the action of sodium amalgam it is readily converted into melilotic acid, which melts at 81° C., and on See also:distillation furnishes its lactone, hydrocoumarin, melting at 25° C. For the relations of coumaric and coumarinic acid see Annalen, 254, p. 181. The homologues of coumarin may be obtained by the action of sulphuric acid on phenol and the higher fatty acids (propionic, butyric and isovaleric anhydrides), substitution taking See also:place at the See also:carbon See also:atom in the a position to the —CO— See also:group, whilst by the condensation of acetoacetic ester and phenols with sulphuric acid the j3 substituted coumarins are obtained. Umbelliferone or 4-oxycoumarin, occurs in the bark of See also:Daphne mezereum and may be obtained by distilling such resins as See also:galbanum or asafoetida. It may be synthesized from See also:resorcin and malic anhydride or from 5 resorcyl aldehyde, acetic anhydride and sodium acetate. Daphnetin and Aesculetin are dioxycoumarins. The structural formulae of coumarin and the related substances are: CHy CH 'CHy NCH I I 0,CO HO See also:NCO 0 Melitotic add. HYdrocoomarin. Umb, liferone CH:CH.CO, H OH Ontwcoumaric add. Coumann. Additional information and CommentsThere are no comments yet for this article.
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