Experiments on the formation of 4 (or 5)-beta-aminoethylglyoxalinne from histidine / by Arthur James Ewins and Frank Lee Pyman.

  • Ewins, Arthur James.
Date:
[1911?]
Catalogue details

Licence: Public Domain Mark

Credit: Experiments on the formation of 4 (or 5)-beta-aminoethylglyoxalinne from histidine / by Arthur James Ewins and Frank Lee Pyman. Source: Wellcome Collection.

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    Experimental. The Action of Concentrated Hydrochloric Acid on Histidine. One gram of histidine hydrochloride was heated in a sealed tube with 2 c.c. of concentrated hydrochloric acid to 270° for three hours. The solution was concentrated and neutralised. To the boiling solution was added an excess of solid picric acid. On cooling, a crystalline precipitate separated, which was collected and freed from picric acid by extraction with ether. The residue, when recrystallised from water, gave 0*2 gram of 4(or 5)-/3-aminoethyl- glyoxaline dipicrate, melting at 233—235°. The Action of Dilute Sulphuric Acid. (a) At 265—270°.—Two grams of histidine monohydrochloride were heated in a sealed tube to 265—270° for three hours with 4 c.c. of a 20 per cent, aqueous solution of sulphuric acid. The reaction product (a dark brown liquid) was treated with sodium carbonate solution until no further precipitate separated, filtered, and the filtrate neutralised and concentrated to about 15 c.c. An equal volume of cold saturated aqueous solution of picric acid was added, and the amorphous precipitate quickly collected. To the filtrate was added 1*5 grams of picric acid in hot saturated aqueous solution. A little resinous precipitate was removed from the hot solution, and the crystalline precipitate, which separated on cooling, was recrystallised from hot water. There w’as thus obtained 0'85 gram of a picrate (m. p. 228—229°), which crystallised in bunched, slightly curved, pointed needles. Repeated recrystallisation did not raise the melting point above 233—234°, and analysis showed the salt to be the hitherto undescribed 4(or 5)-$-aminoethylglyoxaline monopicrate: 0-0978 gave 02L396 C02 and 0 0282 H20. C = 3S’S; H = 3*2. CnH1207N6 requires C = 38’8; H = 3*5 per cent. The monopicrate, on recrystallisation from a large excess of picric- acid solution, readily yielded the dipicrate corresponding in all respects with that described by Windaus and Vogt (loc. cit.). 4(or 5)-/3-Aminoethylglyoxaline Dihydrobromide. The dihydrobromide was prepared by thoroughly shaking the finely powdered dipicrate with ether and a slight excess of dilute hydrobromic acid until all tho dipicrate had disappeared. The aqueous solution of the hydrobromide thus obtained was then freed from picric acid by means of ether, digested with a little animal charcoal, filtered, and evaporated to dryness in a vacuum. The