а 3:5-Dimethyl-1: 2: 4-triazole, CH ̧· NH N N>C•CH2. Dimethyltriazole Nitrate, CH,N,HNO3.-To prepare this substance, 5 per cent. solution of dimethyldihydrotetrazine is saturated at 0° with nitric oxides, and the resulting yellowish solution, after standing for a few hours, evaporated to dryness on the water-bath. The nitrate separates as a colourless, acid, very deliquescent, crystalline mass. It crystallises from water, in which it is very soluble, in colourless needles, and from absolute alcohol, in which it is less soluble, in shining leaflets, melts at 125°, and decomposes explosively on heating. Found N = 35.22. CH2ON, requires N = 35.00 per cent. 8 3 Dimethyltriazole Hydrochloride, CH,N,,HCl, is readily obtained from the nitrate as follows. A concentrated solution is treated with excess of sodium ethoxide, filtered from the precipitated sodium nitrate, the excess of sodium ethoxide removed with excess of alcoholic hydrochloric acid, and the resulting solution evaporated to the crystallising point. On recrystallisation from a mixture of absolute alcohol and chloroform, the hydrochloride separates in indistinct needles or leaflets and melts at 1990. Traces of moisture lower its melting point in a very marked degree. The salt has an acid reaction, is exceedingly soluble in water and very hygroscopic. It was analysed with the following results: Found N31·01; Cl=26·12. CH.N.Cl requires N=31-48; Cl=26 54 per cent. Dimethyl-1: 2: 4-triazole is obtained when the aqueous solution of the hydrochloride is treated with a slight excess of moist silver oxide and the solution evaporated in a vacuum. Evaporation on the waterbath brings about considerable loss owing to the volatility of the base. It is very soluble in water or absolute alcohol, less so in benzene or chloroform, from which it separates in colourless, prismatic needles, or shining leaflets, melting at 142° and boiling undecomposed at 258° under 752 mm. pressure. Found, C=49·70; H=7·41; N=43·08 and 43·18. CH,N, requires C 49-48; H=7-22; N=43.30 per cent. The formation of this substance by the method indicated is probably preceded by the production of dinitrosodimethyldihydrotetrazine, CH, CNN (NOC.CH,, indicated by the transient yellow coloraN(NO)·Ñ2 tion. This rapidly undergoes decomposition in the presence of water with the evolution of nitrogen and formation of the nitrate, thus: Any doubt concerning the constitution of this body is removed by its synthesis from acetamide and acetylhydrazine, which condense on heating, as shown by the following equation: NH2+ CH, CNE H,NNH >C•CH2 =CH ̧·C< N.NH C.CH,+2H2O. When a mixture of acetamide and acetylhydrazine in molecular proportion, after heating to 220° for 4 hours, is subjected to distillation, dimethyl-1: 2: 4-triazole passes over to the extent of 90 per cent. of the theoretical between 255° and 260° under 754 mm. pressure. The product was identified by analysis (N = 43.32 per cent.), melting point (142°), and analysis of its nitrate (N=35-18 per cent.), which melted at 125°. Silver Dimethyltriazole, C,H,N,Ag, is obtained as a white precipitate on adding silver nitrate to a mixture of ammonia and the base in molecular proportion. It is soluble in ammonia, nitric acid, or acetic acid, is fairly stable on exposure to light, and decomposes with evolution of cyanogen on heating.. Found, N = 20·41. CH,N,Ag requires N = 20·62 per cent. 6 In all probability, this salt is a mixture of 4-silver-3: 5-dimethyl1:2:4-triazadien (1:2) and 1-silver-3: 5-dimethyl-1: 2: 4-triazadien (2:4), as will be shown in a later communication. This substance was obtained by Pinner (Ber., 1894, 27, 1006) by the action of hydrochloric acid on 3: 6-diphenyl-1 : 2-dihydro-1 : 2 : 4:5 tetrazine, CH, CNCC,H,, and was termed diphenylisodi >C·CH ̧, hydrotetrazine by him. It is formed in small quantity, together with benzonitrile, diphenyltriazole, and diphenyldiazoxole (dibenzenylisoazoxime), which are the chief products, when benzoylhydrazine is heated at 260° for several hours. The production of the last two compounds appears to be due to the intermediate formation of aẞ-dibenzoylhydrazine, and may be expressed as follows: To the liberation of oxygen the production of benzonitrile is evidently due, thus: 2CH,C<NHANH, + O2 = 2CH, CN + 3H2O. N N (ii). CH, C ¤•NH>C•C2H ̧ = C ̧H ̧•C2 C.C2H2+H2O. Diphenyldiazoxole. The isolation of the products was conducted as follows. Fifty grams of benzoylhydrazine were plunged into an air-bath at 260° and maintained at that temperature during several hours; if raised gradually to 260°, no diphenyldihydrotetrazine is produced. During this process, benzonitrile, together with traces of benzoic acid, distilled off, and was identified in the usual manner. Isolation of sym-3: 6-Diphenyldihydrotetrazine.—The non-volatile residue was finely powdered and extracted with warm 20 per cent. hydrochloric acid so long as anything dissolved. The solution was neutralised with ammonia, filtered, and the precipitate washed with ether and repeatedly crystallised from absolute alcohol. means, shining leaflets (0.5 gram) melting at 263° were obtained, which proved on analysis to be diphenyldihydrotetrazine. Found C-71.03. H=5·29; N = 23·86. By this C14H12N4 requires C-71.19; H=5·08; N=23.73 per cent. Isolation of 3:5-Diphenyl-1: 2: 4-triazole, CH, C NH-The residue was well washed with ether to remove traces of benzoic acid, and then extracted with fairly dilute caustic soda solution so long as anything dissolved. The solution was then treated with a slight excess of dilute sulphuric acid, the precipitate washed with ether, and repeatedly crystallised from alcohol. By these means, flat, prismatic crystals melting at 188° were obtained, which proved on analysis to be hydrated diphenyltriazole. The yield amounted to 18 grams. The substance lost 7.84 per cent. H2O at 100°. C14H1N,HO requires H2O=7·53 per cent. The anhydrous product melted at 192°, and on analysis gave the following results: Found C 75.88; H=5.32; N = 18.75. C14H1N requires C=76·01; H-4·98; N=19.00 per cent. Isolation of Diphenyldiazoxole, CH.C<NNC.CH.-The re 5 sidue, after extraction with caustic soda, was repeatedly crystallised from absolute alcohol, whereby feathery needles melting at 140° were obtained, which, on analysis, proved to be diphenyldiazoxole; the yield amounted to 7.5 grams. Found, C75-49; H=4.80; N = 12.48. C14H10ON2 requires C=75 68; H=4·50; N= 12.61 per cent. Diphenyldiazoxole sublimes on heating in beautiful, fern-like, branching needles. Synthesis of sym-3: 6-Diphenyldihydrotetrazine.-This substance may be obtained in theoretical quantity by heating benzoylhydrazine (3 parts) at 230° under such conditions that the formation of dibenzoylhydrazine cannot occur, namely, in the presence of excess of hydrazine hydrate (1 part). C2H·C<NH•NH2 + H2N HN = + 2H2O. The product, a colourless, crystalline mass, is freed from mother liquor and crystallised from absolute alcohol, from which it separates in colourless, nacreous leaflets, and melts at 260° (Pinner gives 258°). The yield amounts to 96-97 per cent. of the theoretical: Found, N = 23.70. C14H12N4 requires N = 23·73 per cent. The aqueous mother liquor was found to contain ammonia, benzoic acid, and hydrazine hydrate, corresponding to 40 per cent. of that used. Action of Heat on aa-Benzoylphenylhydrazine. The effect of heat on aa-benzoylphenylhydrazine was studied with a view to the production of sym-1:3:4:6-tetraphenyldihydrotetr azine; the desired condensation, however, did not occur. One hundred grams of aa-benzoyl phenylhydrazine were heated at 260° in an air-bath for 6 hours, during which operation ammonia was evolved and a faintly coloured, crystalline substance distilled over which proved to be a mixture of benzoic acid and benzophenone. The dark coloured non-volatile product was digested with benzene, the solution filtered from a black, insoluble residue, heated to boiling, treated with about twice its volume of boiling petroleum (b. p. 140-150°), and filtered while hot from a black, resinous substance. On cooling, a semi-crystalline, resinous mass separated; this was recrys tallised from chloroform, dissolved in alcohol, and boiling water added to the solution, which was then filtered from a dark, resinous precipitate and allowed to cool until the substance which was separat ing was almost white and possessed a crystalline structure; the liquid was then rapidly filtered. The solution, now almost colourless, was heated to boiling, hot water added until a slight permanent cloudiness existed, and then allowed to cool, when an almost colourless, crystalline compound melting at 154° separated. This was freed from mother liquor and recrystallised three or four times from absolute alcohol, then from benzene till its melting point rose to about 160°, and finally sublimed between watch glasses, whereby colourless, shining needles melting at 162° were obtained. These on analysis proved to be benzoylanilide, and not the desired tetraphenylhydrotetrazine. Found, C79-34; H=5.80; N=7·23. C13H11ON requires C=79·19; H=5·58; N=7·11 per cent. The identity of this substance was further established by boiling it with hydrochloric acid, whereby it underwent hydrolysis with production of benzoic acid and aniline, which were identified in the usual manner. An endeavour to produce tetraphenyldihydrotetrazine on lines analogous to those so successful in the case of diphenyldihydrotetrazine, namely, by heating aa-benzoylphenylhydrazine with phenylhydrazine, led to the same result. No traces of a body corresponding in any way to a tetraphenyldihydrotetrazine could be detected. Mixtures of equal parts of aa-benzoylphenylhydrazine and phenylhydrazine heated at temperatures below 230° still contained unaltered benzoylphenylhydrazine, whilst at higher temperatures the decomposition products of the phenylhydrazine rendered the isolation of any compound even more tedious than that just described. In conclusion, I wish to express my thanks to the Government Grant Committee of the Royal Society for pecuniary assistance, and to the Committee of the Davy-Faraday Laboratory of the Royal Institution for allowing me the use of the laboratory. DAVY-FARADAY LABORATORY, CXI.-Isomeric Dibenzyl Ketone Benzalanilines and Deoxybenzoin Benzalanilines. Part II. By FRANCIS E. FRANCIS, Ph.D., B.Sc., Lecturer in Chemistry, University College, Bristol. In a previous paper (Trans., 1899, 75, 865), three isomeric additive products of benzalaniline and each of the two ketones, dibenzyl ketone |