Nitro-, arylazo-, and amino-glyoxalines / by Robert George Fargher and Frank Lee Pyman.

  • Fargher, Robert George.
Date:
[1919?]
Catalogue details

Licence: In copyright

Credit: Nitro-, arylazo-, and amino-glyoxalines / by Robert George Fargher and Frank Lee Pyman. Source: Wellcome Collection.

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    glyoxaline is small, so for the preparation of this substance the reduction of an arylazoglyoxaline containing a substituent in the para-position of the benzene nucleus was undertaken. 2-g-Bromobenzeneazoglyoxaline is the main product of the inter¬ action of ^-bromobenzenediazonium chloride and glyoxaline in aqueous sodium carbonate, only a very small proportion of ^-g-bromobenzeneazo glyoxaline being formed. The reduction of 2-p-bromobenzeneazoglyoxaline with stannous chloride gave 2-aminoglyoxaline in a yield of 56 per cent, of the theoretical, together with aniline, guanidine, some 2-amino-4-^-aminophenyl- glyoxaline, and a small quantity of a base, C9H9N4Br, which is probably 2-5'-b?'omo-2f-aminoamlinoglyoxaline (compare p. 246). 2-Aminoglyoxaline is a monacidic base yielding crystalline salts, but the free base has not been obtained in a crystalline form. CH- ■W (XII.) CH-NH CH-NH >c:nh (XIII.) For this compound, the tautomeric formulae (XII) and (XIII) are possible. The first is supported by the production of a red colour when the substance is mixed with sodium diazobenzene-p- sulphonate, and by the fact that, after treatment with nitrous acid, it couples with phenols. An indication that it can also react according to the formula (XIII)—which represents an unsaturated compound no longer containing the glyoxaline ring—is given by its behaviour towards permanganate, for 2-aminoglyoxaline and all the substituted 2-aminoglyoxalines described in this paper reduce cold aqueous acid potassium permanganate, and in this respect resemble the 2-thiolglyoxalines (compare T., 1911,99, 2173), whereas glyoxaline and its homologues are stable to this reagent, although they reduce alkaline permanganate, giving green solutions. 2-Aminoglyoxaline yields a monoacetyl and a monobenzoyl deriv¬ ative, which are stable to cold aqueous acid permanganate. 2-Aminoglyoxaline does not combine with benzaldehyde in acetic acid solution. Moreover, 2-amino-5-^-aminophenyl-4-methyl- glyoxaline (XVII) yields only a monobenzylidene compound under these conditions, doubtless 2-amino-5-p-benzylideneaminophenyl-4- methylglyoxaline. This behaviour, therefore, serves to differentiate between 2-aminoglyoxalines and homologues of aniline, and is employed later in the determination of constitution. The action of benzenediazonium chloride on 4-methylglyoxaline proceeded quite differently from its action on glyoxaline. Instead of the 2-substituted arylazo-compound being formed predominantly,
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