FARGHER ARYLAZOGLYOXALINECARBOXYLIC ACIDS. 159 tion one of the carboxylic acid groups being displaced by the arylazo-group. The same product namely 4-p-bromobenzeneazo-2-phenylglyozaline-5-carboxyl.ic acid is obtaingd when the mono-carboxylic acid is substituted for the dicarboxylic acid in the reaction. Similar results are obtained with 2-methylglyoxaline-4 5-dicarb-oxylic acid although in this case the reaction appears to proceed rather more slowly. It had been anticipated that as the possibilities of benzidine formation had been very largely excluded the reduction of these compounds with cold stannous chloride solution would lead to the corresponding amino-acids and that although subsequent trans-formation into the glyoxalone might be anticipated in the oase of the 2-methyl derivative unless indeed the presence of the adjacent carboxylic grouping proved inhibitive in that of the 2-phenyl derivative stability might reasonably be anticipated as it had already been ascertained that the reduction of 4-p-bromobenzene-azo-2-phenylglyoxaline led to a substance which almost certainly possessed the constitution 5 -amino-4-( 2/-amino-5’-bromophenyl)-2-phenylglyoxaline.The reaction follows a somewhat novel and unexpected course the second carb-oxylio grouping being eliminated during the process of benzidine formation the acids yielding the same products as the correspond-ing non-carboxylated glyoxalines. I n view of these results it appeared to be of interest to examine the reduction of 2-p-bromo benze~neazoglyoxaline-4 5-dicarboxylic acid under similar conditions.The tendency towards benzidine formation is here sufficiently less pronounced to permit of the isolation as main product of 2-p- brornobenzenehydrazoglyoxaline-4 5-dicarboxylic acid. It has already been shown that glyoxalinedicarboxylic aoid and its %methyl homologue are not acted on by a warm mixture of nitric and sulphuric acids (T. 11319 115 217). 2-Phenylgly-oxaline-4 5-dicarboxylic acid reacts under these conditions but as the composition of the product indicated that substitution had taken place only in the benzene nucleus its further examination has been omitted. This has however proved not to be the case. E x P E R I Y E. N T A L. 4-p-Bromo benzeneazo-2-phenylglyoxaline-5-car boxylic A cid. A .solution of 6.8 grams of p-bromoaniline in 130 C.C.of 10 per cent. hydrochloric acid was diazotised with 2.88 grams of sodium 6 160 PARGHER ARYLAZOGLYOXALINECJARBOXYLIC ACIDS. nitrite and added to an ice-cold1 solution of 9'23 grams of 2-phenyl-glyoxaline-4 5dicarboxylic acid in 400 C.C. of water containing 67.2 grams of sodiym carbonate crystals when gradual separation of a deep orange preoipitate took place. After five hours this was collected. It consisted of the sodium salt of 4-p-bromo bertzene-azo-2-phenylglyoxaline-5-car boxylic acid admixed with that of the unchanged acid. Separation was readily effected by crystallisation from water containing a little sodium carbonate the former dis-solving very sparingly in cold water. The corresponding acid was readily obtained on acidification and was further purified by crystallisation from aloohol.4-p- Bromo benz eneazo-2 -phenylgEyoxaline-5-car boxylic acid is in-soluble in water and only very sparingly so in alcohol from which i t separates in glistening red needles which darken on heating above 160° and effervesce and decompose a t 210° (corr.). It dis-solves in sulphuric acid with the production of an eosin-red color-ation (Found C= 51.6 ; H = 3.3 ; N = 14-8. C,6H,,0,N,Br requires C=51*6; H=3.0; N=15*1 per cent.). The sodium salt separates from water as a felted mass of orange needles containing 3H20 (Found loss a t 60° in a vacuum =12*0. C16Hl,0,N,BrNa,3H20 requires B20 =11*8 per cent. In dried material Na =5*6. C,,H,,O,N,BrNa requires Na = 5.8 per cent.).The same product was obtained1 when 2-phenylglyoxaline-4-carb-oxylic acid was substituted for the dicarboxylic acid. Reduction.-Four grams of the acid were triturated with 25 C.C. of concentrated hydrochloric acid and gradually treated with 14 O.C. of stannous chloride solution,* the trituration being con-tinued until the completion of the experiment. Evolution of carbon dioxide quickly became evident. The insoluble stanni-chloride was collected freed from tin by means of hydrogen sulphide and the resulting solution evaporated to low bulk under diminished pressure when separation of a crystalline hydrochloride took place. This was purified by recrystallisation from water con-taining a little hydrochloric acid and formed colourless needles melting a t 255O (corr.).This was fully identified by analysis (Found C ~ 4 5 . 1 ; H=4*0; N=13.6. Calo. C=44*8; H,=3*8; N = 13.8 per cent.) by the preparation of the triacetyl derivative (Found N=12*2. Calc. N=12-3 per cent.) and by its reactions (T. 1919 115 257) as 5-amino-4-(2/-amino-5'-bromophenyl)-2-phenylglyoxaline (T. 1920 1\17 671). In an attempt to characterise and compare the two products more completely it was found that sodium acetate yielded a grey precipi-tate which redissolved on adding a little acetic acid and warming, * Prepared as described in the earlier communications F'ARGHER ARYLAZOGLYOXALINECARBOXYLIC ACIDS. 161 and separated in clusters of minute needles melting a t 1 6 1 O (corr.). This proved to be the monoacetate of the base (Found C'=52*1; H =4*8 ; N = 14.1.C,,Hl3N,Br,C2R,O2 requires C = 52.4 ; H =4*4 ; N = 14-4 per cent.). Ammonium oxalate yielded a grey precipitate, which darkened rapidly on warming the solution. Addition of excess of sulphuric acid to the concentrated solution of the hydro-chloride caused on stirring the separation of a sparingly soluble sulphate which crystallised in minute flattened prisms. Ammoniacal silver nitrate was reduced in the cold. After separation of the above hydrochloride no further orystal-line material was obtained as the solution decomposedl rapidly on exposure. The residue after removal of tin from the soluble stanni-chlorides amounted to only 0.5 gram and consisted mainly of ammonium chloride although a little p-bromoaniline (0.07 gram) was isolated and identified by means of the acetyl derivative.Reduction with sodium hyposulphite in alkaline solution gave p-bromoaniline in a yield amounting to 52 per cent. of the theoretical but no other pure substance was isolated. The form-ation of small quantities of a blue dye similar t o that obtained by the reduction of nitroglyoxaline was observed. 4-pBromo b enxeneaz o-2-methylglyoxaline-5 -car boxylic A cid, This substance was prepared in a similar manner to the 2-phenyl homologue. Starting with 7.52 grams of 2-methylglyoxaline-4 5-dicarboxylic aoid the precipitate which formed was collected ( A ) and the filtrate acidified with hydrochloric acid when 2 grams of pale orange crystals were obtained. These dissolved somewhat sparingly in alcohol and separated in glistening orange needles.The precipitate ( A ) was suspended in water and acidified with hydrochloric acid when it gave 7 grams of an orange powder con-sisting of a mixture of the azo-compound and the unchanged acid. Separation was effected by extraction with and crystallisation from alcohol in which the original acid is practically insoluble, when 5.4 grams of 2-methylglyoxalinedicarboxylic acid were recovered unchanged. I n a later experiment the reaction was allowed to proceed for several hours but although the yield of the product was larger it was much darker in oolour and more dificult to purify. The ultimate filtrates from the recrystallisation from alcohol yielded a small proportion of a product approximating in composition to 4 5-bis-pbromobenzeneazo-2-methylglyoxaline but owing t o the ease with which resinification took place it was not obtained pure 4-p-Bromobenzeneazo-2-methylglyoxaline-5-c~r boxylic acid separ-ates from alcohol in which i t is somewhat sparingly soluble in orange needles containing 4R20.It is very sparingly soluble in water and dissolves in concentrated sulphuric aoid with the pro-duction of an orange-red coloration. On heating i t darkens rapidly above 160° (Found loss a t 60° in a vacuum=3.2. $H,O requires 2.8 per cent. I n dried material C=43.0; H=3.2; N= 17.8 ; Br = 25.4. C,,H,O,N,Br requires C = 42.7 ; I3 = 2.9 ; N = 18- 1 ; Br = 25.8'5 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-me thy1 -4 - ( 2 '-amino-5 '-bromo phen yl) -5 -glyoxalone hydroohloride which melted a t 2 7 2 O (corr .) the mix-ture with the reduction product of 4-p-bromobenzeneazo-2-methyl-glyoxaline melting a t 272O in the same bath (Found C=39*2; H = 3.9 ; N = 13.7.C,,H,,ON,Br,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-p-Bromobenzenenzo~lyoxal~ne-4 5-dicar boxylic A cid. 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 a t 250° (corr.). It dissolved but sparingly in alcohol and separated in bunches of minute red needles which melted a t the same temperature and contained lC,H,O (Found in air-dried material C = 40.9 ; H = 3.7 ; N = 14.6; Br = 21.3; loss a t looo in a vacuum = 11.5. C,,H,O,N,Br,C,H,O requires C = 40.5 ; H = 3.4 ; N = 14.55 ; Br = 20.75 ; C2H,0 = 12.0 per cent.I n dried material C = 39.3 ; H=2*4. Reduction.-The reduction was carried out as in the previous instances. The decolorised solution from 4 grams of the azo-deriv-C,,TI,O,N,Br requires CL=38.95; H=2.1 per cent.). * This is possibly 2 4 5-tris-p-bromobenzeneazoglyoxaline 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 a t 203O (corr.) (Found loss a t looo in a vacuum = 2.9. C,,H,O,N,Br,~H,O requires H,O = 2.6 per cent. I n dried material C=39-1 39-0; H=3-1 3.0; N=16*2 16.3; Br=23*8.CIIH,O,N,Br requires C'= 38.7 ; H= 2.7 ; N = 16.4 ; Br = 23.4 per cent .). In aqueous solution the following characteristic reactions were 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 oomposition and properties therefore indicate that the sub-stance is 2-p-bromobenzenehydrazoglyoxaline-4 5-dicar boxylic acid. The solution remaining after precipitation of the above sub-stance was freed from tin and evaporated to dryness leaving 0.7 gram of residue. From this by suitable means 0.35 gram of p-bromoaniline was isolated and identified whilst the residual solution then developed a strong odour of ammonia on warming with alkali.Nitration of 2-Phenylglpoxaline-4 5-dicarboxylic A cid. 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 oooled 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 a t 266O (corr.) (Found C = 47.9 ; I3 = 2.6 ; N = 15.3. Cl,H70,N requires ( 2 ~ 4 7 . 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. I n view of the predominating negative character of the glyoxalinedicarboxylic acid substituent the substance is in all probability 2-rn-nitrophenylglyoxaline-4 5-dicarboxylic acid. The corresponding amino-acid was obtained by reduction wit 164 NTERENSTETN THE CONSTJTUTTON OF CATECHTN. PART TTI. 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 i t separates in powdery crystals containing 2H,O. After treatment with nitrous acid i t develops a deep red coloration on addi-tion to sodium P-naphthoxide (Found loss a t 1100= 12.4. C,,H,04N,,2H,0 requires H,O = 12.7 per cent. I n dried material : N = 16.2. C,1H,04N requires N = 16.2 per cent .). WELLCOME CHEMICAL RESEARCH LABORATORIES. [Receiucd January 14th 1921.