AMMONIUM BED OTHER IMIDOSULPHITES. 1099 CXVIIL- Ammonium and other Imidosulphites. By EDWARD DIVERS and MASATAKA OGAWA. THE fact of the existence of ammonium imidosulphite as a product of the decomposition of the amidosulphite by very gentle heating, 2NH,*S0,*NH4 = NH, + NH(SO,NH,),, was brought before a meeting of the Society last session (Proc., 1900, 16, 113). Thepresent paper consists of a fuller account of this salt and other imidosulphites than could then be given. Ammonium amidosulphite, from which the imide salt is derived (Trans., 1900, 77, 327), is readily formed by the unioii of sulphur dioxide and ammonia, but is so unstable as to be largely decomposed by the unavoidable heating it suffers when these gases come together, unless cooled ether be used as their solvent.On keeping the dry salt a t a temperature of about 3 5 O , its decomposition goes on, and ammonia escapes for some hours. There is left a mottled orange mass of waxy consistence already described in the earlier paper (Zoc. cit., p. 333), which is difficult to attack with solvents other than water, because i t adheres very firmly to the vessel and must not be exposed to the air during treatment. By protracted digestion with successive portions of 9 0 per cent. spirit, aided by scraping with a pointed glass rod and vigorous shaking, it can, however, be nearly all dissolved up, although only very sparingly soluble. The first portions of the solution are coloured, and contain a salt, the presence of which interferes with the prepara- tion of the imidosulphite from them The later colourless extracts yield the imidosulphite when they are evaporated in the vacuum desic-1100 DIVERS AND OCtAWA: cator, but not quite pure.Much better results are got by beginning the treatment with warm 95 per cent. spirit, used in successive por- tions, until the residue is a colourlees powder: and only then resorting to the 90 per cent. spirit and carrying on the digestion at about 50'. The solution thus obtained deposits almost pure imidosulphite as it cools, and the mother liquor can be used with advantage again and again to dissolve out more of the salt, although in that case the crys- tals which separate are somewhat impure. These, can be purified by washing with absolute alcohol containing much ammonia to dissolve out the foreign salt (more soluble in presence of ammonia), and then dissolving up in warm 90 per cent. spirit and recrystallising.The original mother liquor yields more imidosulphite, but impure, when it is either artificially cooled (as by ice and salt) or is evaporated in the desiccator. This impure salt can be purified in the may just described. All the ammonium irnidosulphite is finally washed with ammoniacal alcohol, drained on a porous tile under close cover, and dried in a desiccator over potash. The quantity of pure salt actually obtained in this way approaches that of a fourth only of the weight of decomposed amidosulphite taken, but the total production of imidosulphite will no doubt prove to be very much greater. AnccZysis.-The salt,, 0.4240 gram, distilled with potash, yielded ammonia, 0.0817 gram, and then, after heating for some time in a tube with hydrochloric acid under pressure and again distilling with potash, 0.03755 gram more ammonia.Simple distillation with potash of 0.4912 gram of another portion of salt gave 0.0939 gram of am- monia, and then, after oxidation by means of bromine followed by hydrochloric acid and potassium chlorate, 1 *2886 grams of barium sulphate. The calculated and found percentages are : Ammonia Imide Total nitrogen. nitrogen. nitrogen. Sulphur. NH(S02NH,), ... 15.64 7.82 23.46 35.75 Found 7-29 23.15 - ............ 15.86 .............. 15.74 - - 36.02 It will be seen that the analysis establishes, not -only the composi- tion of the salt t o be 3NH3,2S0,, but also its imide constitution.Properties.-It occurs in minute, micaceous needles. Heated very slowly in a tube, it soon begins to decompose into volatile substances and a residue of sulphur, ammonium snlphate, aud the 9 normal ammonium imidosulphate, [NH(S03NH,),]. Even when the tempera- ture is raised t o 150°, no fusion takes place. The sublimates which form during the heating begin t o appear at about SOo, and consist apparently of ammonium pyrosulphite, [(NH,)2S,0,], and the unchangedAMMONIUM ANb OTHER IMIDOSULPHITES. 1101 imidosulphite, [(NH,)2S20,NH]. The salt is insoluble in alcohol, and in this respect is unlike ammonium amidosulphite, which is very soluble as ethyl ammoniumsulphite and ammonia. The salt is only moderately deliquescent and, freshly prepared, is neutral to litmus." It has a mild, unpleasant, sulphurous taste, which distinguishes it from the salt occurring with it, more freely soluble than it in 95 per cent.spirit, and already referred to. It is freely soluble in water, but slowly decomposes into thiosulphate and amidosulphate. This change beginning at once, the solution gives all the reactions of n thiosulphate. It goes on also in presence of hydrochloric acid, which when hot hastens its completion. Barium thiosulphate has been prepared from the solution, and amidosulphuric acid and ammonium amidosulphate also obtained from it. Quantita- tive determinations of the sulphur, sulphur dioxide, and amidosu1phat.e formed on boiling with hydrochloric acid gave results in agreement with the following equation : 2NH(SO,NH,), + 2HCl =fz 2NH,*S03NH,+2NH,C1 + SO, + 8 in which the SO, and S represent decomposed thiosulphuric anhydride.Potassium Imidosulp?&e, --It has already been stated when detailing the analysis of the ammonium salt, that that salt yields just two- thirds of its nitrogen as ammonia when boiled with potassium hydr- oxide in aqueous solution. I n accordance with this fact, it has been found that potassium imidosulphite is obtained when, to the ammoniuni salt dissolved in 70 per cent. spirit, alcoholic potash is added until the solution just renders red litmus paper permanently blue on exposure to air. The salt soon separates as minute, micaceous crystals firmly adherent to the glass. After repeated mashing with-absolute alcohol, the salt has been found to remain alkaline to litmus, quite possibly, however, because of the presence of a trace of tripotassium salt, as happens in the case of imidosulphates. The imidosulphite unlike the corresponding potassium imidosulphate, NH(SO,IC),, is very soluble in water, and its solution gives the imidosulphite reactions of the ammonium salt.It has, too, the sulphurous taste of tbat salt'. I n the analysis, nitrogen was determined by the combustion method, sulphur by oxidation, as in the analysis of the ammonium salt, and potassium by ignition with sulphuric acid, with the following results : * As first obtained by us last year and then described, the salt had an acid re- action and was exceediugly deliquescent ; but as it showed a deficiency in ammonia (22.2 instead of 23.5 per cent.), and as its potassium derivative was not acid, we indicated our expectation that when obtained in a purer state the salt would prove to differ somewhat in properties from what we had then found' VOL, LXXIX 4 F1102 AMMONIUM AND OTHER IMIDOSULPHITES+ Potassium.Nitrogen. Sulphur. NH(SO,K), .............. 35.29 6-33 28.96 Found ..................... 35.17 6.74 28.88 - 6.93 - ,, ..................... Barium Ammonium 1midosulphite.-When the orange mass of de- composed amidosulphite is dissolved in water and mixed with baryta water in such quantity as to leave undecomposed some of the ammon- ium imidosulphite it contains, the filtered solution when concentrated in the desiccator deposits the double salt in minute, micaceous crystals. Only barium and sulphur were determined.The results agree with those calculated for Ba(S02NHS02NH,),. Barium. Sulphur. BaN4H1,S40, ........................... 29.85 2’7.89 Found .................................... 29.94 26.90 In the Proceedings (1900, 16, 104), the existence of this salt was indicated, but by mistake it had been taken to be a salt of the acid N2H,S20,, and was accordingly formulated as Ba(N,H3S,0,),,2H,0. It is soluble in water, and its solution behaves as that of an imido- sulphite, being precipitable by baryta (N,H,S,O, salts are not), and besides at once gives off ammonia when moistened with potassium or barium hydroxide solution. The treatment of the orange mass of decomposed ammonium amido- sulphite with 95 per cent. spirit as a preliminary to dissolving out the main quantity of imidosulphite with 90 per cent.spirit, yields yellow, alcoholic solutions, which on evaporation in the desiccator deposit crys- tals which are short, thick prisms almost cubicalin appearance and about 2 mm. across. They are thus quite unlike the minube, micaceous needles of ammonium imidosulphite. They are yellow, but the colour is adven- titious. They can be purified and rendered white by putting them into 95 per cent. spirit and then almost saturating this with ammonia, while the containing flask is kept immersed in cold water. I n this alcoholic ammonia, they are very sensibly soluble. The solution is decanted, and the treatment repeated until only a small quantity of white, powdery salt remains, principally imidosulphite. The solutions left for a while in open flasks, and then exposed in the desiccator over sulphuric acid, lose most of the ammonia, and the crystals reform from the solution.Washed with alcohol, they are left quite colourlessI The mother liquors evaporated in the desiccator yield crude, yellow crystals again, which can be recrystnllised from alcoholic ammonia as before. These crystals are recrystallisable without change, and have alsoMcCRAE : ETHYL SEC.OCTYL TARTRATE. 1103 been prepared by us in two successive winters, yet they give analytical results which are closely concordant with the remarkable empirical formula 4NH,,580, or N,H,,S,O,,. Nitrogen. Sulphur. N,H12S,0,0 .............................. 14.43 41.24 Found in 1900 ........................... 14.11 41-14 . . . . . . . . . . .. . . . . . . . . . . . . . . 14.36 40.02 ,, in 1901 ........................... 14.02 41.02 ........................... 14.40 These crystals are neutral and have a bitter taste, not a sulphurous one. They are freely soluble in water, and very deliquescent. The solution is unstable, and in some of its reactions greatly resembles that of ammonium imidosulphite. With potassium hydroxide, the salt evolves ammonia a t once, but analyses of potassium salts pre- pared from it in 70 per cent. alcoholic solution have given discordant results. A striking difference from an imidosulphite is that its fresh solution gives no barium precipitate, even in presence of ammonia, Also that in freshly prepared solution, i t does not decolorise iodine solution, and only slowly decolorises cold acid permanganate. It also does not give the ferric chloride coloration of a thiosulphate, which the imidosulphite does give. I t s solution becomes very acid after n time, and then smells much more strongly of suphur dioxide than a similar solution of imidosulphite. The crystalline matter having nearly the composition expressed by 9NH38SO,, mentioned in our paper on ammonium amidosulphite (Trans., 1900, 77, 334) we believe t o have been the present salt mixed with imidosulphite and amido- sulphate. On a future occasion, me hope to be in a position to report upon the constitution of the substance me have here described. ? I 9 , 29 - 7 )