See also:alcohol . It is prepared artificially by
See also:heating aceto-ortho-coumaric acid (which is formed from sodium salicyl aldehyde) or from the
See also:action of acetic anhydride and sodium acetate on salicyl aldehyde (
See also:Sir W . H . 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 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 perfumery for the preparation of the Asperula essence . On boiling with concentrated
See also:caustic potash it yields the 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 solution, to melilotic acid . It forms addition products with bromine and hydrobromic acid .
By the' action ofphosphorus pentasulphide it is converted into thiocoumarin, which melts at roe C.; and in alcoholic solution, on the addition of
See also:hydroxylamine hydrochloride and soda, it yields
See also: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 place at the
See also:carbon 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 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 .
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