2044 FRANK : ~ ~ N T R I B U T I ~ N ~ TO OUR KNOWLEDGECCXIV.-Cont.1.ibutions to o w K~iotvledye of theSulphide Dyestufls. P a r t I.By GEORGE HERBERT FRANK.SINCE the introduction of Vidal black (by R. Vidal, of Paris, in1893), which, as is well known, is prepared by fusing togetherp-aminophenol (or paminophenol and other compounds) with sodiumpolysulphide, a large number of these secalled " sulphide " dye-stuffs have been produced in a similar manner from aromaticcompounds of varied constitution. The application of these colour-ing matters, especially to cotton, is of so simple a character, andthe colours obtained are of so permanent a nature, that thesecompounds now constitute one of the most important groups ofartificial dyestuffs. Although considerable insight has been gainedas to the reactions occurring in their formation (Vidal, Mon.Sci.,1903, [iv], 17, i, 427; Pollak, Zeitsch. F a d . Ind., 1904, 3, 233, 253;Gnehm and Kaufler, Ber., 1904, 37, 2617, 3032), the subject isbeset by considerable difficulty, for the dyestuffs are as a ruleamorphous, of a comparatively insoluble nature, do not yield well-characterised derivatives, and are accordingly not easily isolated ina pure condition.During some experiments on the subject it was discovered thatthe leuco-compounds of many sulphide dyestuffs react with chloro-acetic acid, and that the substances thus obtained, when oxidised,yield interesting colouring matters, differing considerably in pro-perties from the parent substance. These new carboxyl derivativesare readily soluble in alkalis, pyridine or phenol, moderately so inboiling alcohol or acetic acid, but insoluble in dilute acids. !l%eyare well-defined colouring matters, giving shades similar to thoeOF THE SULPHIDE DYESTUFFS.PART I. 2045produced by the original sulphide dyes, and can be r e d i l y dyed onwool, but differ from the parent sulphide dyes in that they havevery little affinity for cotton.Among other points of interest attached to these mbstances itseemed possible that their closer examination would yield an insightas to the true molecular weight of the sulphide dyestuffs fromwhich they were obtained, a point which would be of considerablehelp in regard to the vexed question of their constitution.The following investigation deals with the well-known colouringmatter, immedial-indone, which is manufactured by heating togetherpaminophenol and o-toluidine with an aqueous solution of sodiumsulphide.In order to purify the commercial product, it wasrepeatedly washed with warm water, treated with dilute hydro-chloric acid until the liquor was faintly acid, and well washed.Fifty grams of the finely powdered product were reduced withsodium hydroxide and dextrose a t 60-70° in the usual manner,and treated with 20 grams of a solution of sodium chloroacetate.An increase in temperature took place, and after fifteen minutesair was aspirated through the liquid in order t o oxidise the leuco-compound. The liquid was now neutralised with dilute hydrochloricacid, the precipitated dye collected, extracted with warm sodiumcarbonate solution, the extract acidified, and the dye collected anddried; the product was now extracted with warm aniline, filteredfrom a slight residue, the solution neutralised with acid, and theprecipitate again extracted with dilute sodium carbonate solutionand acidified.As molecular-weight determinations in pyridine andnitrogen and sulphur estimations indicated that this product witsnot quite pure, it was submitted to a further treatment with warmaniline and extraction with dilute aqueous sodium carbonate in themanner above described, and finally dried in a vacuum desiccator.The compound obtained in this way contained no ash, and experi-ments indicated that it was now pure.It was of a deep blue,bronzy colour, readily soluble to a blue solution in aniline, pyridine,phenol, alkalis, or concentrated sulphuric acid, and sparingly so inhot glacial acetic acid or hot alcohol. Experiment indicated theabsence of an amino-group, and, unlike the original immedial-indone,it had no affinity for cotton when dyed in a sodium sulphide bath,neither had its sodium salt any affinity for cotton, but the lattercould be dyed on wool in the manner of an acid colour, giving abright blue colour.After being dried at 98O, it was analysed:0.1241 gave 0.2494 CO, and 0.0459 H,O.0.28009.1121 ,, 0.1376 BaSO,. S=16-88.C = 54.8 ; H =4*11.,, 17.3 C.C. N2 at 13O and 757.7 mm. N=7*402046 FRANK : CONTRIBUTIONS TO OUR KNOWLEDGE0,1312 gave 0.1559 BaSO,.S = 16.72.C17H1404N,S2 requires C = 54.4 ; H = 4.0 ; S = 17-07 ;N = 7.48 per cent.0.5 Gram of the substance was treated with 10 C.C. of N-sodiumhydroxide, and the solution was made up to 500 c.c.; by titrationwith N / 10-hydrochloric acid and employing phenolphthalein asindicator, the acidity of the compound was first determined, andthe neutral liquid thus produced was then treated with sodiumtartrate and reduced with standard titanium chloride :Found, NaOH = 21.12 per cent. of the weight of the dye.Y, H2=0.529 ,, J , 9 , ?,C17H140,N,S2 requires NaOH = 21-39 ; H,= 0.5347 per cent.Hence 189.9 parts of the colouring matter neutralise 40 parts ofsodium hydroxide, and for the reduction of 378.2 parts, 2 parts ofhydrogen are required.A determination of the molecular weight was carried out by thecryoscopic method :0-0854, in 10.3 of phenol, gave A t = - 0*14O.C,7H1404NzS2 requires M.W.= 374.When fused with sodium hydroxide, the substance undergoes aninteresting change, for not only is sulphur thus removed, but alsothe carboxyl groups are eliminated. A blue compound insoluble inwater or alkalis is thus produced. When reduced, this yields aleuco-derivative, but, unlike the corresponding leuco-derivatives ofthe sulphide dyestuffs, possesses no affinity for cotton.To obtain some further indication as to the nature of the reaction,a quantitative experiment was carried out as follows :0.5 Gram of the carboxyl derivative was fused at 200° with con-centrated aqueous sodium hydrate until a colourless pasty mass,consisting of the leuco-compound of the new substance, was pro-duced. The product when cold wits diluted with water, the mixtureneutralised with acid, and the colouring matter collected andwashed.An 'estimation of the sulphur present gave the followingresult :S = 14.89 per cent.M.W. = 377-4.0-154 gave 0.1668 BaSO,.Hence 21'5 parts of the substance contain 32 parts of sulphur.If from the found molecular weight of the carboxyl derivative wesubtract 2(CH,-CO2H) + S = 150, the new substance should have amolecular weight of 227, which is in fair agreement with the aboveresult. This experiment shows that one atom of sulphur can beremoved from the molecule of the original carboxyl derivative, butthat on the other hand, the removal does not destroy the chromo-phoric group of this compoundOF TEE SULPHIDE DYESTUFFS. PART I.2047As &medial-indone is formed from the indophenol (I) obtainedfrom paminophenol and o-toluidine, so the resultant dyestuff maybe expected to possess the skeleton (11) :NIf we assume that, as is most probable during the reaction, sulphurenters in the o-position with respect to the nitrogen atom, and thatthe phenolic group is replaced by the thiol group, leuceimmedial-indone would have the constitution (111), and immedial-indoneformula (IV) :NH N(111.)Such a constitution would offer a ready explanation of theexperiments given above. This compound would readily yield withchloroacetic acid a leuco-dicarboxylic derivative having the formula(V), and the colouring matter would be represented by (VI).NHCO,H*CH,*NHI I I/\/\/\S*CHz*CO,HCH3S(V.)NI- IVI.1This investigation therefore indicates that the most probableconstitution of immedial-indone is that given above ; further experi-ments on this difficult subject are in progress.DEPARTMENT OF TINCTORIAL CHEMISTRY,THE UNIVERSITY,LEEDS