XC.—The residual affinity of coumarin as shown by the formation of oxonium salts
Journal of the Chemical Society Transactions
COUYARIN, which is only sparingly soluble in cold water, readily dissolves in concentrated hydrochloric or hydrobromic acid, and from the latter solvent Ebert long ago isolated an extremely unstable hydrobromide which could only be kept at low temperatures and dissociated into its generators before it could be analysed (Annalen, 1884, 226, The authors, on adding a strong solution of chloroplatinic acid to the coumarin dissolved in concentrated hydrochloric acid, have obtained a well-defined,
... a well-defined, crystalline substance, which has the composition of a coumarin platinichloride, 4CSH,0"H,PtCI"4H20. This compound, which separates in yellow needles, is quite stable when dried at the ordinary temperature, but is dissociated into its generators by water ; it can be recrystallised from concentrated hydrochloric acid, but only in the presence of excess of chloroplatinic acid. The substance was prepared for analysis by washing with cold concentrated hydrochloric acid and drying in a desiccator over quicklime until it ceased to evolve hydrogen chloride or water. 0.2938 gave 0.4304 CO, and 0.0911 H,O. C = 39-96 ; H = 3.44. 0.2880 " 0.6240 CO, " 0.0850 H20. C=40*15 ; H = 3.28. 0.2568 " 0.2094 AgCl. C1= 20.17. 0.2004 " 0.0367 Pt. Pt = 18.32. 0.3274 " 0.0597 Pt. Pt = 18.23. 347). C"H"0"H2PtC1"4H,0 requires C = 40.52 ; H = 3.19 ; Cl= 20.00 ; Pt = 18.30 per cent.