The absorption spectra of some substituted pyrazines and their salts / by Frank Tutin and Frederic W. Caton.

  • Tutin, Frank.
Date:
[1910?]
Catalogue details

Licence: In copyright

Credit: The absorption spectra of some substituted pyrazines and their salts / by Frank Tutin and Frederic W. Caton. Source: Wellcome Collection.

    10/16 (page 2531)
    0'2417 gave 0'2570 BaS04. H2S04 = 44*7. C16H12N2,2H2S04 requires H2S04 = 45'8 per cent. Although the result of this analysis is not in very close agreement with the theoretical figures, owing to the readiness with which the salt dissociates, it nevertheless proves conclusively that the salt has the formula indicated above. Salts of 2 : §-Diphenylpyrazine.—The monohydrochloride of this base is described in the preceding paper (p. 2501). It is a prac¬ tically colourless, crystalline solid. The monohydrobromide, how¬ ever, is pale yellow, whilst the mono sulphate is quite colourless. The dihydrochloride and disulphate were obtained in the form of solutions, both of which were yellow, but no positive indication of the formation of a dihydrobromide could be obtained. 2 : Q-Diphenylpyrazine monohydrobromide, C4H2N2(C6H5)2,HBr, separated in pale yellow needles on passing hydrogen bromide into a solution of the respective base in a mixture of ethyl acetate and alcohol. Like the previously described salts, it readily dissociated : 0T408 gave 0'0840 AgBr. HBr = 25'7. C16H12N2,PIBr requires HBr = 25’9 per cent. 2 : ^o-Diph enylpyrazine monosulphate, C4H2N2(C6IT5)2,H2S04, crystallised in quite colourless needles on adding concentrated sulphuric acid to a solution of 2: 6-diphenylpyrazine in glacial acetic acid: 0*1316 gave 0'0934 BaS04. H2S04 = 29*8. C16H12No,H2S04 requires H2S04 = 29‘7 per cent. Salts of pp’-Dimethoxy-2 : b-diphenylpyrazine.—The monohydro¬ chloride, monohydrobromide, and monosulphate of ^7-dimethoxy- 2 : 5-diphenylpyrazine crystallised readily, and the disulphate was also obtained in crystals, although it was very unstable. A solution of the dihydrobromide was obtained as a deep violet-coloured liquid by saturating a solution of £>jf-dimethoxy-2 : 5-diphenylpyrazine in glacial acetic acid with hydrogen bromide; and this salt also appeared to be formed on passing dry hydrogen bromide over the solid base. No positive evidence of the formation of a dihydro¬ chloride could be obtained. pp'-Dim ethoxy-2 : b-diph enylpyrazine monohydrochloride, C4H2N2(C6H4-OMe)2,HCl, was formed by saturating a warm solution of the pyrazine derivative in glacial acetic acid with hydrogen chloride. On cooling, the salt separated in bright yellow needles: 0-3191 vave 0*1374 AgCl. HC1 = 10*9. CVH4602N2,HC1 requires HCl = il*l per cent. Phis sail dissociated much more readily than the corresponding