N1 Diazobenzolimide, C. HN, is obtained according to the equation It forms a yellowish oil, which must be distilled in vacuo with the aid of a current of steam. Exposed by itself to a higher temperature, it decomposes with detonation. It is remarkable for its stupefying ammoniacalaromatic odour. H, Ethyldiazobenzolimide, CT, NN, is analogous in its properties, and is formed in a similar manner. Products of Decomposition of Diazobenzol Compounds. The transformations which the molecule of diazobenzol undergoes under the influence of various reagents are numerous. The products often represent some peculiar classes of entirely new compounds; more frequently, however, they belong to the phenyl- and benzol-group. I will describe a few of them somewhat more fully. It has already been mentioned that, on boiling with water, nitrate of diazobenzol is broken up into nitrogen, phenylic acid, and nitric acid. Hydrobromate of diazobenzol undergoes an analogous decomposition, viz., CH, N2 HBr+H2O=N2+C, H, O+HBr. 2 2 2 6 Treated with alcohol, nitrate of diazobenzol is decomposed in the following manner : 2(C ̧H ̧N2, NHO,)+C2H2O=C ̧¤ ̧+CH ̧(NO2),O+C2H ̧O+N ̧+H2O. Nitrate of diazo- Alcohol. Benzol. benzol. 6 Dinitrophenylic Aldehyde. On dissolving sulphate of diazobenzol in a small quantity of concentrated sulphuric acid, it gives rise to the formation of a new sulpho-acid which I propose to call disulphophenylenic acid, 4 2 The excess of sulphuric acid may be removed from the new acid by means of carbonate of barium. The new barium-salt crystallizes in beautiful prisms. Its composition must be expressed by the formula CHS, H, Ba, О.. The free acid obtained by the addition of sulphuric acid to the barium-salt is deposited in warty masses of radiating crystals which deliquesce in the air. Disulphophenylenic acid is four-basic, and is capable of forming four series of salts. The silver-salt forms, however, an exception, its composition being expressed by the formula C, H, S, Ag, 0,. Disulphophenylenic acid, like phosphoric acid, appears to be capable of existing in different modifications, possessing different powers of basicity. Diazobenzolimide in alcoholic solutions is decomposed by nascent hydrogen, generated with zinc and sulphuric acid in the following manner :— On adding to an aqueous solution of nitrate of diazobenzol levigated carbonate of barium, a feeble evolution of gas ensues, which lasts for several days, until the original compound has been completely decomposed. Two new substances are formed, which are very differently soluble in alcohol, and can thus readily be separated. The easily soluble compound, which I will call phenyldiazobenzol, crystallizes from alcohol in yellowish warty masses; from water (in which it dissolves very difficultly) in small rhombic prisms. The difficultly soluble one, which I propose to call phenyldidiazobenzol, crystallizes in reddish-yellow needles. The following equation expresses the formation of these two bodies: : I. 2(C H ̧ N2, NHO,)+H2O=С12 H2 N2O+N2+2NHO,. 6 4 Nitrate of diazobenzol. 2 12 10 Phenoldiazobenzol. II. 3(CH, N, NHO,)+H, O=C1, H1, N, O+N2+3NHO,. 4 18 14 4 Phenoldidiazo- On looking at these formulæ, it becomes evident at a glance that both compounds contain phenylic acid and diazobenzol; viz. Both compounds are weak acids; the first being capable of forming a well-characterized silver-salt, which is obtained in the form of a blood-red precipitate when an ammoniacal solution of phenoldiazobenzol is treated with nitrate of silver. On heating the platinum-salt of diazobenzol mixed with carbonate of sodium in a retort, chlorobenzol is obtained, the formation of which may be expressed as follows: : A similar decomposition ensues when the dibromide is heated with carbo nate of sodium, CH, N, HBr, C, H, Br+N2+ Br2. 2 Dibromide. Bromobenzol. The same change may also be effected by simply boiling an alcoholic solution of the dibromide. The peculiar and often remarkable properties of the diazobenzole-compounds have induced me to try whether analogous bodies could not be prepared also from bromaniline, nitraniline, dibromaniline, &c. Experiment has fully borne out theory. These analogous diazo-substitutions exhibit, however, so much resemblance to the normal diazobenzol compounds, that I should frequently have to repeat almost literally what has already been said of the latter, were I to describe these compounds in detail. I may be permitted, however, to mention a remarkable and interesting fact which their investigation prominently brought out. There are, as is well known, two isomeric nitranilines-the alphanitraniline of Arppe, and the betanitraniline of Hofmann and Muspratt. This isomerism, I found, extends itself to their respective nitrogen-substitution compounds, and even to their products of decomposition. On heating, ex. gr., the dibromide of alphadiazonitrobenzol with alcohol, the following change takes place : CH, (NO) N2 HBr, C, H, (NO2) Br+ N2+ Br2. a-dibromide. 2 Bromonitrobenzol. The bromonitrobenzol thus obtained is identical with that prepared by Cooper from benzol derived from coal-tar. It crystallizes in the same form, and fuses, like the latter, at 126° C.; sulphide of ammonium converts it into bromaniline, which crystallizes in octahedra, and is identical with the bromaniline of Hofmann obtained from bromisatine. Bromonitrobenzol, prepared in a perfectly similar manner by the decomposition of the dibromide of betadiazonitrobenzol, possesses, however, widely different properties. The a-bromonitrobenzol just described crystallizes in long needles, whilst the new benzol-derivative, which I will designate by the name of 3-bromonitrobenzol, forms well-developed prisms, the fusing-point of which lies at 56°C. Sulphide of ammonium converts it likewise into bromaniline; but this base differs in its physical properties entirely from the bromaniline obtained by Hofmann. It forms a colourless oil, which combines with acids, and gives rise to a series of beautiful salts, which in their turn differ greatly from the ordinary bromaniline salts in their physical properties. I will distinguish this bromaniline by calling it ẞ-bromaniline from that obtained. by Hofmann, which I will call a-bromaniline. It deserves to be mentioned briefly that there exist likewise two isomeric chloronitrobenzols (alpha and beta) obtained by heating the platinum-salts of the respective diazonitrobenzole with carbonate of sodium, €, H, (NO) N2, HCl, PtCl=C, H ̧ (NO2) C1+N2+PtCl2. 8 3 2 Alpha-nitrochlorobenzol furnishes, when reduced by means of sulphide of ammonium, the ordinary (alpha-) chloraniline; beta-chloronitrobenzol yielding a new base of like composition (beta-chloraniline), distinguished from the former by its oily nature. Corresponding diazo-compounds can readily be prepared from the homologues of aniline and other analogous bases by submitting them to a treatment exactly similar to that which in case of aniline yielded diazobenzol. Thus I have obtained the diazo-compounds from toluidine, naphthalidine, and nitranisidine, C, H, (NO). I have abstained from entering more fully into a description of their physical and chemical habitus, as well as the respective products of decomposition to which they give rise, since they offer nothing characteristically new*. All compounds already described have been derivations from monoatomic amido-bases. I have on a former occasion † had an opportunity of pointing out that the action of nitrous acid upon diatomic bases, such as nitrate of benzidine, is perfectly analogous to that which gives rise to the formation of nitrate of diazobenzol from nitrate of aniline. Whilst, however, in the last-mentioned reaction only one atom of nitrous acid exchanges its nitrogen for three atoms of hydrogen of the original compound, six atoms of hydrogen are exchanged for two atoms of nitrogen when nitrous acid reacts upon nitrate of benzidine. Respecting these compounds I shall only briefly describe a few general properties and a few products of decomposition. 12 Sulphate of Tetrazodiphenyl, 2€12 H ̧ Ñ, зSH ̧ O̟, crystallizes in white or slightly yellowish-coloured needles, which are very soluble in water, and almost insoluble in strong alcohol and ether. On boiling the alcoholic solution, the following decomposition takes place : I have already had occasion to describe diphenylenic acid (diphenylenealcohol) obtained by decomposition, analogous to that of nitrate of tetrazodiphenyl with water, and I have therefore only to refer to what has been stated on that occasion. The decomposition which tetrazodiphenyl undergoes on boiling with * In a former notice (Proceedings, Jan. 22, 1863) I briefly described the formation of nitrate of naphthol, which by its decomposition with water gave rise to the long-soughtfor naphthyl-alcohol, E1 H, O. † Proceedings, Jan. 22, 1863. alcohol differs from the previous one, and takes place according to the equation 2 C1, H. N1, 3S H2O1+4C, H, O=2C12 H10 +4C, H ̧O+3S H2O,+8N. 12 6 12 10 Sulphate of tetrazodiphenyl. Alcohol. Diphenyl. Aldehyde. The diphenyl which results from this reaction is identical with the compounds obtained by Fittig from bromobenzol. A comparative examination of the two demonstrates this most unmistakeably. The transformation which sulphate of tetrazodiphenyl undergoes when it is heated with a small quantity of strong sulphuric acid is likewise of great interest. Two new sulpho-acids are formed, which I shall call The following equation explains tetra- and tri-sulphodiphenylenic acid. €12 H, N1+4S H ̧ O ̧=С12 H ̧, § ̧ H ̧ →1+N1 6 2 12 16 12 The separation of these two acids is based upon the unequal solubility of their barium-salts. The process is, however, somewhat complicated, and I therefore abstain from describing it. Both acids are capable of combining with bases in various proportions. Tetrasulphodiphenylenic acid is octobasic. The lead-salt crystallizes in beautiful needles, and has the composition C1, H., S, Pb, O. Trisulphodiphenylenic acid appears to be hexabasic. I have as yet only prepared the former acid in a free state. It crystallizes in white needles, which are readily soluble in water and alcohol. 12 16 Tetrabromide of the Tetrazodiphenyl, C12 H ̧ N, 2HBr, Br ̧. 12 This compound forms crystals of an orange colour with curved faces. On heating with alcohol, it splits up according to the equation C12 H. N1, H2 Br=C12 H. Br2+N1+Br ̧. 6 8 Tetrabromide. Bromodiphenyl. Bromodiphenyl crystallizes from alcohol and ether (in which it is rather difficultly soluble) in beautiful prisms which fuse at 164° C. This substance can be distilled without undergoing decomposition. Bromodiphenyl has also been obtained by Fittig (according to a private communication) by the action of bromine upon diphenyl. 12 The platinum-salt of tetrazodiphenyl, C, H, N., H, Cl, (PtCl,),, forms small yellow plates, which furnish, when heated with carbonate of sodium, chlorodiphenyl closely resembling the analogous bromine-compound. |