Ortho-para-isomerism in the preparataion of diaminodiphenylmethane / by Harold King.

  • King, Harold
Date:
1920.]
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Licence: Public Domain Mark

Credit: Ortho-para-isomerism in the preparataion of diaminodiphenylmethane / by Harold King. Source: Wellcome Collection.

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    at 218°. The author has only once succeeded in reproducing the needle form, by inoculating a hot saturated solution of the anilide with the powdered, re-solidified material melting at 224°. Both forms separated simultaneously, the needle form in much the smaller proportion. The identity of the 2:4/-diacetylaminodiphenylmethane was proved by direct comparison with a sample prepared by StaedeTs method (Annulen, 1894, 283, 162) from 2:4/-dinitrodiphenyl- methane. Both showed the characteristic double melting point, and a mixture of the two showed no depression (Found: N = 10'l. Calc.: N = 10-l per cent.). 2 :4/-Diaminodiphenylmethane is readily soluble in hot benzene, but crystallises well from the cold solution in pearly leaflets. It melts at 88—89° (corr.) and boils at 222°/9 mm. The dibenzylidene derivative is readily soluble in ether, and is precipitated on addition of light petroleum as an oil. 4 :4/-Diaminodiphenylmethane, free from the isomeride, is best prepared through the intermediary of the dibenzylidene derivative. It crystallises well from benzene in clusters of rectangular plates melting at 92—93° (corr.) and boiling at 232°/9 mm. 4 : i'-Di-ami/no-Z : 21 -azoxydiph eny Ira ethane. Pure 2 : 2/-dinitro-4 :4/-diaminodiphenylmethane (1 gram) was suspended in 20 c.c. of alcohol, and 4 grams of crystalline, hydrated sodium sulphide, dissolved in 4 c.c. of water, were added. The solution was boiled for half an hour, and, when cold, the product, which separated in glistening, orange needles, was collected. The yield was 0'45 gram. 4 :4/-Diamino-2 : 2/-azoxydiphenylmethane melts and decomposes at 265° (corr.) (Duval, Compt. rend., 1905, 141, 198, gives 272°). The only solvent at all suitable for its recrystallisation is pyridine (Found: C = 64‘9; H = 53. Calc.: C = 65’0; H = 5'0 per cent.). It forms a stable dihydrochloride crystallising in microscopic, six-sided leaflets, which are readily soluble in water without separation of the base. It has no definite melting point (Found: H20 = 8-6; Cl = 208. C13H]20N4,2HC1,HH20 requires H20 = 7 3; Cl = 20-8 per cent.). The author desires to thank Dr. H. H. Dale, F.R.S., for per¬ mission to complete these results in the Biochemical and Pharmaco¬ logical Laboratories of the Medical Research Council, Hampstead. The Wellcome Chemical Research Laboratories, London, E.C. [Received June 3rd, 1920.]