40 MELDOLA ON NITROSO-b-NAPETHOLSULPHONIC ACID. VI.-On Nitroso-P-Nuphtholsulphonic Acid. By RAPHAEL MELDOLA. THE ideas which have prompted the investigation which has led to the discovery of this nitroso-sulphonic acid are briefly as follow :-The colouring-mat,ters described in the preceding paper are as already stated of but little value as dye-stuffs and it therefore became of interest t o investigate the derivatives of these bodies containing acid radicles it being uow well known that the tinctorial value of t3he “diazo-colours” is greatly increased by the introduction of one OF more such radicles into one or both of the aromatic nuclei linked together by the diazo-group. As the “@-naphthol violet” did not appear to readily form a sulphonic acid by the direct action of sulphu-ric acid upon it I was led to iuvestigate the action of nitrous acid upon the sulphonic acids of the naphthols with a view to producing by this means the nitroso-sulphonic acids which would furnish MELDQLA ON NITROSO-P-NAPHTHOLSULPHONIC ACID.4 1 means of forming bodies of the type of the ‘‘@naphthol violet ” containing the group HSOs. When a solution of sodium nitrite is mixed with a solution of a salt of P-naphtholsulphonic acid the two salts being in exact mole-cular proportions on adding dilute HC1 to the well-cooled mixture a solution of a deep orange colour is formed and no trace of nitrous gas is evolved. These facts led me to believe that some definite reac-tion had taken place and on adding t o the orange solution a large excess of caustic soda a green colour was produced and on stand-iiig in the cold for some time minute green needles of the sodium salt of nitroso-P-naphtholsulphonic acid separated out.The extreme solubility of this sodium salt in water the readiness with which it decomposes on evaporating the solution on a water-bath and the difficulty of isolating in a state of purity a substance requiring excess of caustic soda for its precipitation led me to seek for some other method of obtaining a salt fit for analjbis. This process which will be described later on is based upou the insolubility of the Ba or Ca salt of the new acid. The p-naphtholsulphonic acid employed in these experiments was prepared from commercial @-naphthol purified by distillation and crystallisation from toluene till it possessed a melting point of 122”.This @-naphthol was mixed with about 2-43 times its weight of strong sulphuric acid and heated on a water-bath for about half a2u hour. As the free acid was not required the contents of the flask were poured into a large bulk of water neutralised with milk of lime boiled and filtered. The calcium salt was then converted into the ammonium salt by decomposition with ammonium carbonate and filtering off the calcium carbonate. The filtrate on cooling de-posits a certain amount of thc ammonium salt and a further quantity can be obtained by evaporating t,he mother liquor. The ammonium salt was chosen because of the readiness with which it crjstallises, and the ease with which it can thus be obtained in a state of perfect purity.Ananzonium P-.naphtholsu~TLoiiate crystallises in long flat transparent prisms with pointed extremities or when a large bulk of the solution is allowed to cool slowly in large plates sometimes half an inch i n length. Analysis showed it to possess the formula C,,H,.HO.NH,SO,. At 2 4 O 100 parts of water dissolve nearly 3 parts of the salt. The latter is very stable and can be boiled with dilute sulphuric or hydro-chloric acid without parting with its ammonium group. Barium Nitroso-/3-Naphtholsdph.onate. To prepare this salt 16-18 parts of distilled water are poured upon One part of the finely powdered ammonium salt and a standard solu 42 MELDOLA ON NITROSO-P-NAPHTHOLSULPHONIC ACID. tion of sodium nitrjte added in the proportion of one molecule of the latter salt to one of the sulphonate.Dilute hydrochloric acid is then gradually poured into the well-cooled solution till it shows a strongly acid reaction and all the ammonium salt has dissolved. The deep orange solution is then made alkaline with ammonia and barium chloride fiolution added as long as a precipitate forms. The latter is collected on a filter where it remains as a bright green paste which is well washed first with cold and finally with boiling water till a few drops of the filtrate no longer give a crimson colour on the addition of dilute hydrochloric or sulphuric acid. Tho green paste is then transferred to a flask and agitated with dilute hydrochloric acid, which changes its colonr to orange and on standing for some time a heavy crystalline deposit settles down which is collected and washed with cold water.Both the green paste and orange crystals are barium salts of nitroso-P-naphtholsnlphonic acid and will be desig-nated by their respective colours. The orange salt may be purified by two or three crystallisatioiis from boiling water or in cases where there is much associated impurity the hot aqueous solution may be precipitated by ammonia and the green salt collected washed and again converted into the orange salt by dilute hydrochloric acid and recrystallised. Analyses of Orange Ba salt. I. 0.4944 gram dissolved in hot water and decomposed by K,SO* gave 0.1742 gram BaS04. 11. 0.5914 gram gave 0.2097 gram BaS04. 111. 0.3309 , 0.1168 7 9 IT;. 0.8440 gram fused with RHO and KNO gave 0.5852 gram BaS04.V. 0.36'75 gram fused as above gave 0.2670 gram RaS04. VI. 0.2951 gram dried at loo" burnt with lead chromate gave 0.0632 gram H,O (1 mol. of water of cryatallisation sub-tracted) and 0.3930 gram CO,. Water of Crystallisation,. VII. 0.7153 gram dried at loo" and heated in an air-bath t o 140-150° till the weight was constant lost 0.017 I gram H,O. VIII. 0,6453 gram treated as above lost 0.0168 gram HzO MELDOLA ON NITROSO-/3-NAPHTHOLSULPHOXIC ACID. 4 3 Theory. Found (mean). C Z 0 . . . . . . . . . . 240 36.41 36.32 H, . . . . . . . . 12 1.82 2-37 N,. 4.25 - . . . . . . . . . 28 Ole . . . . . . . . 160 24.30 S,. . . . . . . . . . 64 9.71 9.74 Ba . . . . . . . . 137 20- 78 20.76 H,O . . . . . . . . 18 2.73 2.49 659 100~00 --These results show tJhat the orange salt has the formula :-ClOH,.HO.NO. so3 >Ra H,O, C,,H,.HO .NO. SO A determination of Ba in a specimen of the anhydrous salt dried at 140-150" gave 21.33 per cent. ; theory requiring 21.37. The orange salt crystallises in large tufts of flattened needles with a golden lustre crystals nearly three-quarters of an inch long having sometimes been obt,ained by the slow crystallisation of a large bulk of the solution. It is but very sparingly soluble in cold water; a t 30" 100 parts of water dissolve about. two parts of the salt. The green Ba salt was prepared for ana,lysis by dissolving the orange salt in a considerable quantity of hot water and adding ammonia. The bright green bulky precipitate thus obtained wa,s seen under the microscope to consist of minute needle-shaped crystals.Analysis showed it to possess the formula :-C1,H5.NO< S03>Ba,2H20. 0 The action of. an alkali upon the orange salt is therefore represented by the equation :-(ClOH,.NO.HO.SOJ),Ba + NH4H0 = CloH5.NO<S03>Ba 0 + C1oH,.NO.HO.NH*SO3 + HZO. The ammonium nitroso-$naphtholsulphonate formed in this reaction is most obstinately retained by the green Ba salt so that for the purposes of analysis it was found necessary t o add sufficient BaCl to the ammoniacal iolution to decompose the whole of the ammonium salt present. The green salt is then collected and well washed with boiling water in which it is practically insoluble. Analysis of CSreen Ba Salt. I. 0.370 gram (di-ied a t looo) gave on decomposition with dilute H,SO1 0.2039 gram BaSO, 44 MELDOLA ON NITROSO-P-NAPHTHOLSULPHONIC ACID.11. 0.6156 gram fused with KHO and RNO gave 0.3396 gram 111. 0.3029 gram (dried a t 100') burnt wit,h lead chromate gave 0.3153 gram COz and 0.0422 gram H,O (water of crystal-lisation subtracted). BEI SOa. Water of Crystnllisution. IV. 0.5198 gram dried at loo" and in an air-bath to 240-250" till the weight was constant lost 0,0438 gram H20. V. 0.4056 gram treated as above lost 0.0354 gram H,O. Theory. Found. C1" 120 28.30 28.31, H5 . . . . . . . . 5 1.1 7 1.54 N 14 3.30 0,. . 80 18.88 S 32 7.55 7.3 7 Ba 137 32.31 32.37 2H2O . . . . . . 36 8-49 8.57 (mean) ---424 100.00 The wat,er of crystallisation is not given off completely till the salt is heated to the temperature mentioned above (240-250") when partial decomposition takes place but the weight remains constant a>s long as this temperature is not exceeded.Nitroso-P-naphtholsnlphonic acid thus forms two classes of salts represented by the green and orange Ba salts. In cases where large quantities of a salt of this acid are required calcium chloride can be used for precipitating the ammoniacal solntion of the acid after its first formation from ammonium P-naphtholsulphonate by the action of nitrous acid (NaNO and HCI). By decomposing a solution of the Ba salt with an equivalent quantity of €€,SO4 and evaporating the solution in a vacuum the free acid was obtained in microscopic orange nodular crystals extremely soluble in water and decomposed by heating to a very moderate temperature in a dry tube so that its melting point could not be determioed.Of the other salts of nitroso-6-naphtholsulphonic acid I hare pre-pared the following :-Silver anzrrionium (double) salt formed by adding AgNOa to a solution of the ammonium salt of nitroso-P-naphtholsulphonic acid in the presence of an excess of ammonia. Dull olive-green microscopic needles decomposed by boiling water. Analysis gave the formula :-CloH,.NO.NHaO.AgS03 + CloH,.NO.NH4O.NHISO + HZO MELDOLA ON NITROSO-P-NAPHTHOLSULPHONIC ACID. 45 Found 15-87' per cent. Ag 9.69 per cent. S ; theory 15.83 par cent. Ag 9-58 per cent. S. Magnesium salt formed by decomposing the orange Ba salt with an equivalent (2 mols.) of MgS04 and adding ammonia to filtrate.Dull orange needles moderately soluble in cold readily soluble in boiling, water. Analysis gave the formula :-Found 7.27 per cent. Mq 16.70 per cent. H,O; theory 7-29 per cent. Mg -16.41 per cent. H20. Water of crystallisation not given off till 250". Large scaly crystals doll green by reflected light orange by transmitted light. Modcmtely soluble i n cold water more readily soluble iu hot water. Analysis gave the formula :-Zinc salt formed i n the same manner as the Ng salt. Found 17.81 per cent. Zn 8.86 per cent. S. and 1462 per cent,. H,O ; theory 17.56 per cent. Zn 8.64 per cent. S 14.59 per cent. H,O. Water of crystallisation only given off completely at 280" with partial decomposition of the salt. Lead salt preeipitated on adding a solution of lead acetate to a solution of the sodium or ammonium salt of nitroso-6-naphtholsulphonic acid acidulated with acetic acid.Minute ochreous needles insoluble in boiling water. Analysis gave the formula :-C10H5.XO< gO,>Pb,H,O. Found 43.60 per cent. P b ; theory 43.48 per cent. Pb. No loss of water at 250". Copper 8aZts.-On adding a solution of CuSO4 to a solution of the free nitroso-sulphonic acid containing an excess of H2S04 a bulky brown gelatinous precipitate almost insoluble in boiling water, separates out. On suspending this gelatinous salt in cold water and adding ammonia a double copper-ammonium salt settles down aftor some hours in the form of small brown glistening scales. The consti-tution of this salt has not been determined. Analysis gave 17.92 per cent.Cu and 8.55 per cent. S. An attempt was made to prepare an acetyl derivative of nitroso-/3-naphtholsulphonic acid by acting upon the sodium salt of acetyl-(3-naphtliolsulphonic acid with sodium nitrite and dilute hydrochloric acid bui the acetyl-group appears to be eliminated in the course of the reaction as on adding ammonia and barium chloride the ordinar 46 MELDOLA ON NITROSO-&NAPHTHOLSULPHONIC ACID. green Ba salt was precipitated. An attlempt to prepare a nitroso-derivative of methyl-/3-naphthol in a similar manner was also unsuccessful. The nitroso-group is readily reducible by any reducing agent but I have not yet been able to obtain the corresponding nitro-sulphonic acid, either by the action of dilutIe nitric acid or of an alkaline solution of potassium ferricyanide the molecule apparently completely breaking up under the action of these reagents.On agitating a solution of the nitrososuIphonic acid with 1 mol. of bromine the lnttcr is absorbed, but no definitely crystalline brom-nitroso acid was separable. Nitroso-&naphtholsnlphonic acid is very easily decomposable. Cons fit ution of hi;ltroso-P-Nap h t holsu lp honk Acid. I have made numbers of experiments with a view to determine the constitiition of this acid. The free acid when repeatedly eva-porated with dilute nitric acid gave no phthnlic acid neither did the nitroso- nor amido-acids when oxidised with an alkaline solution of potassium permanganate. Phthalic acid was however obtained by repeatedly evaporating the nmido-acid wit.h dilute nitric acid.This result is of interest as showing that in nitroso- and amido-/3-naphthol-sulphonic acid all these substitnents are in the same benzene-ring. In their recently published monograph upon naphthalene Reverdin and Nolting (“ Ueber die Const’itution des Naphtalins und seiner Abkomm-linge,” Genf. 1880 p. 25) assign to B-naphtholsulphonic acid a formula in which the HSO3 and HO-groups are in different benzene-nuclei but no reasons are assigned for adopting this constitution. I n a communication t o this Society last November Armstrong gave reasons for believing that in this acid the two substituents are both in the same benzene-ring being in the two $-positions. Although I have made repeated attempts to confirm this view by oxidising 6-naphtholsulphonic acid with an alkaline solution of permangznate 1 have not succeeded in obtaining phthalic acid from this compound.The production of ph thalic acid however from amido-@-naphthol-sulphonic acid in the nianner above described goes to support Arm-strong’s view of the constitution of this sulphonic acid and shows that the nitroso-acid has the NO constitution :-N MELDOLA ON NITROSO-P-NAPHTHOLSULPHONIC ACID. 4 7 Among the reactions of nitroso-B-naphtholsulphonic acid which I have investigated the most interesting appears to be that with the phenols and certain primary and secondary monamines. The phenol or amine is dissolved in glacial acetic acid the finelypowdered barium or calcium salt of the nitroso-acid added and after the addition of a small quantity of sulphuric acid the mixture is warmed.The follow-ing colouring-matters have been obtained in this manner :-Resomii~.oZ and ordinaryphenoi! give a deep blue clianging to red on dilutim with water. Diphenylamine gives a similar blue which retains its colour on dilution but becomes red on neutmlising with an alkali. BenzyI-ol-rza~hthyzainine gives a fine red which is not changed by dilution. These bodies are probably built on the type of the @-naphthol-violet described in the last paper and containing HSO in the naphthalene-group. Their value as dyes does not appear however to be increased by the presence of the acid radicle. I hope to investigate these substances more fully at a future period. On mixing solxtions of ammonium nitroso-P-naphtholsulphonate and ammonium sulphite and allowing the mixture to stand for some hours in the cold white scaly crystals separate out which have not yet been further investigated.Anaido-P-naphthol.szc1phonic Acid. This acid was prepared by boiling a solution of the nitroso-acid with tin and hydrochloric acid removing the tin by sulphuretted h-ydrogen and evaporating the cold solution in a vacuum. The acid then separates out in the form of long white needles which after one or two washings with cold water are sufliciently pure for analysis :-0.2380 gram fused with KHO and KNO gave 0.2380 gram 0.4984 gram gave 0.4928 gram BaS04 = 13.57 per cent. S. BaSOd = 13.73 per cent. S. Theory for CloH5.NH2.H0.HS03. Found (mean). S . . . . . . . . . . 13-38 Its aqueous solution and especially that of its salts oxidises on exposure to the air and turns brown. A hot solution undergoes this change rapidly. The melting point of the acid could not be determined as it decomposes on heating. I n concluding this paper I may take the opportunity of announcing that I have recently succeeded in obtaining an iodine derivative of &naphthol by acting upon this substance dissolved in glacial acetic 13-65 Amido-P-naphtholsulphonic acid is readily soluble in water 48 HAMILTON ON THE FORMATION OF CARBON ETC. acid with iodine in the presence of lead acetate. I hope shortly to lay before the Society an account of this substance and some of its derivatives. It is also my pleasing duty to express my thanks to the firm of Brooke Simpson and Spiller in whose laboratory at the Atlas Woi.ks these investigations have been conducted