Arylazoglyoxalinecarboxylic acids / by Robert George Fargher.

  • Fargher, Robert George.
Date:
1921.]
    4:-ip-Bromobenzeneazo-2-methyIgIyoxaIine-o-carboxylic acid separ¬ ates from alcohol, in which it is somewhat sparingly soluble, in orange needles containing 4H20. It is very sparingly soluble in water, and dissolves in concentrated sulphuric acid with the pro¬ duction of an orange-red coloration. On heating, it darkens rapidly above 160° (Found: loss at 60° in a vacuum = 3-2. JH20 requires 2-8 per cent. In dried material, C = 43'0; H = 3‘2; N = 17*8; Br = 25-4. CuII902N4Br requires C = 42*7; H = 2-9; N = 18‘l; Br = 25'85 per cent.). Reduction.—On reduction, as described in the previous case, the evolution of carbon dioxide was again noticed. The insoluble stannichlorides, which accounted for almost the whole of the start¬ ing material, yielded 2-methvl-4-(2/-amino-5/-bromophenyl)-5- glyoxalone hydrochloride, which melted at 272° (corr.), the mix¬ ture with the reduction product of 4-p-bromobenzeneazo-2-methyl- glyoxaline melting at 272° in the same bath (Found: C = 39’2; 11 = 3-9; N = 13*7. C10H10ON3Br,HCl requires C = 39’4; H = 3*85; N = 13-8 per cent.). The identity was further confirmed by isolation of the base and picrate, and by comparison of the reactions of the bases from the two sources, both of which gave the reactions previously described (T., 1920, 117, 677). 2-^-Bromobenzeneazoglyoxaline-^: 5-dicarboxylic Acid. This was prepared in the manner already described. The pre¬ cipitate, which formed fairly rapidly, was collected after three hours. The filtrate, on acidification, gave a further quantity of the azo-compound admixed with the unchanged acid. The pre¬ cipitate was boiled with water containing a little sodium carbonate, leaving a dark brown residue insoluble in sodium carbonate or sodium hydroxide.* The extract, on acidification, gave an orange- red precipitate, which, after boiling with alcohol and drying, darkened above 200° and melted and effervesced at 250° (corr.). It dissolved but sparingly in alcohol, and separated in bunches of minute, red needles, wmch melted at the same temperature and contained 1C2HgO (Found, in air-dried material: C = 409; H = 3'7; N = 14*6; Br = 2F3; loss at 100° in a vacuum = 11*5. CnH704N4Br,C2Hf)0 requires C = 40”5; H = 3'4; N = 14*55; Br = 20’75; C2H0O = 12’0 per cent. In dried material: C = 39‘3; II = 2‘4. CnIl704N4Br requires C = 38-95; H = 2-l per cent.). Reduction.—The reduction was carried out as in the previous instances. The decolorised solution from 4 grams of the azo-deriv- * This is possibly 2:4: .Ytris-p-bromobonzeneazoglyoxaline.
    ative, on dilution with water, gave a precipitate amounting to 3 grams. This dissolved sparingly in water, dilute acids, and the usual organic solvents, but rather more readily in 50 per cent, acetic acid, from which it separated in clusters of minute needles. On heating, these darkened rapidly above 190° and effervesced at 203° (corr.) (Found: loss at 100° in a vacuum = 2*9. CnH904N4Br,JH20 requires H20 = 2'6 per cent. In dried material: C = 39:l, 39*0; H = 3*l, 3-0; 1ST = 16*2, 16*3; Br = 23*8. CnH904N4Br requires C = 38*7; H = 2*7; N = 16*4; Br = 23*4 per cent.). In aqueous solution, the following characteristic reactions w*ere observed : with warm dilute hydrogen peroxide, development of a reddish-brown coloration; with warm ferric chloride, a turbid, orange solution; with warm dilute nitric acid, a bright yellow coloration, whilst silver nitrate and Fehling’s solution were reduced on warming. The composition and properties therefore indicate that the sub¬ stance is 2-p-bromobenzenehydrazoglyoxaline-k'.'o-dicarboxylic acid. The solution remaining after precipitation of the above sub¬ stance was freed from tin and evaporated to dryness, leaving 07 gram of residue. From this, by suitable means, 0*35 gram of ^-bromoaniline was isolated and. identified, whilst the residual solution then developed a strong odour of ammonia on warming with alkali. Nitration of 2-Phenylglyoxaline-4:\'5-dicarboxylic Acid. A solution of 2 grams of the acid in a mixture of 4 c.c. of nitric acid (D 1*4) and 4 c.c.of sulphuric acid was heated for eight hours on the water-bath, then cooled, poured on ice, and the precipitated product crystallised from 120 parts of boiling water. It separates in small needles, very sparingly soluble in cold water or the usual organic solvents, but readily so in alkalis, with the production of a red coloration. On heating, the substance effervesces at 266° (corr.) (Found: C = 47*9; H = 2*6; N = 15*3. CnH706N3 requires C = 47*7 ; H = 2*5 ; N = 15*2 per cent.). The composition of the product therefore indicates that nitration has taken place only in the benzene nucleus, and that, as in the case of glyoxalinedicarboxylic acid and its 2-methyl homo- logue, there is no tendency for displacement of the carboxylic by the nitro-group. In view of the predominating negative character of the glyoxalinedicarboxylic acid substituent, the substance is in all probability 2-m-nitroyhenylglyoxaline-A : b-cli carboxylic acid. The corresponding amino-acid' was obtained by reduction with
    sodium hyposulphite in alkaline solution. It dissolves readily in dilute mineral acids, but very sparingly in the usual organic solvents, 50 per cent, acetic acid, or hot water, from which it separates in powdery crystals containing 2H20. After treatment with nitrous acid, it develops a deep red coloration on addi¬ tion to sodium /3-naphthoxide (Found: loss at 110° = 12'4. CnHf)04N3,2Ho0 requires II.20 = 12-7 per cent. In dried material: N = 16'2. CnII904N3 requires N = 16’2 per cent.). Wellcome Chemical Research Laboratories. [Received, January 14th, 1921.] PRINTED IN CHEAT BRITAIN BY THE CORNWALL PRESS, LTD., PARIS OARI'EN, STAMFORD STREET, LONDON, S.E. I.
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