2248 GAZDAR AND SMILES : AROMATIC HYDROXY-SULPHOXIDES.ccxxxv1.- -Aromatic Hycl~oxy-sulp hoxides.By MAUD GAZDAR and SAMUEL SMILES.IN the study of the sulphination of certain phenolic ethers (Smilesand Le Rossignol, Trans., 1908, 93, 745) several thionyl derivativesof these substances were obtained, and it was found that thesemethoxy- and ethoxy-sulphoxides when dissolved in concen tratedsulphuric acid may be converted by excess of phenolic ether into thetriarylsulphonium salts. Later investigation of the correspondinghydroxy-derivatives showed that the reaction is not generally applic-able to these substances, for, whilst di-p-hydroxyphenyl sulphoxide(Smiles and Bain, Trans., 1907, 9 1, 11 18) yields the trihydroxyphenyl-sulphonium base, the di-p-hydroxym-tolyl sulphoxide does not (Smilesand Hilditch, Proc., 1907, 23,161). The exceptional behaviour of thispcresol sulphoxide is of peculiar interest, for the corresponding dimethylether, ( C,H3Me-OMe),S0, readily furiishes the triarylsulphoniurnderivative.Although the so-called ‘‘ steric ” conditions which are setup by substitution in the aromatic nucleiis are known to be capable ofretarding this reaction (Smiles and Le Rossignol, Zoc. cit.), it cannot besupposed that their influence is the cause of the inactivity of thisp-cresol sulphoxide. For it is evident from previous experience of‘‘ steric hindrance ” that, if there be any difference in reactivitybetween a phenol and its ether, it is the latter that should be lessreactive, whereas in the present case the reverse relation holds.It is a remarkable fact that of the eleven hydroxy- or methoxy-phenyl sulphbxides which have been hitherto examined, all givebrilliantly coloured solutions in concentrated sulphuric acid, andi t therefore seemed probable that in effecting the condensation of thesulphoxide with the phenolic ether by means of this reagent, someintermediate compound is formed, and that it is the reactivity of thissubstance that determines the formation of the sulphonium salt.As a preliminary step in the investigation, we have found itnecessary to extend the range of material available, since very littleis known of the aromatic hydroxy-sulphoxides, only one, apparently,having been obtained in a pure condition.The present paper deals with the aulphoxides of p-cresol, p-chloro-phenol, and o-chlorophenol, The investigation is not yet complete,but the results are now published, since one of US is unable to carryon the work.E x P EB I YE NT A L.p-CresoZ-m-sulpho;L.ide, (OH*C,H,Me),SO.(Me : OH : SO = 1 : 4 : 3.)The sulphination of p-tolyl methyl ether with sulphurous acid andaluminium chloride yields the sulphoxide and a small quantity OGAZDAR AND SMILES. AHOMATIC IIYDROXY-SULPHOXIDES, 2249sulphinic acid, the sulphonium base, which is the final product ofnormal sulphination, being entirely suppressed (Smiles and LeRossignol, Zoc. cit.). On applying this method to p-cresol, similarproducts were obtained; but the yields of sulphoxide were poor, henceadvantage was taken of the stronger sulphinating power of thionylchloride.Although this reagent is apt to yield sulphonium saltsi f allowed to act too energetically, we find that by preserving suitableconditions excellent yields of the sulphoxide are obtained.Fifteen grams of powdered aluminium chloride were dissolved in an ice-cold solution of 20 grams of p-cresol in 50 C.C. of carbon disulphide, andthen 20 grams of thianyl chloride were gradually added. The mixturewas set aside in a desiccator, and, aftor the lapse of twenty-four hours,the greater portion of the reaction product-evidently a double salt ofthe sulphoxide with aluminium chloride-had separated in the form ofa yellow, viscous mass. During the next twenty-four hours a furthersmall quantity of this product separated ; the supernatant layer ofcarbon disulphide was then decanted, and the residue decomposedwith crushed ice.After being mixed with dilute hydrochloric acid,the mass was treated with a current of steam to remove carbondisulphide and unattacked cresol. After this operation, the contentsof the flask mere cooled, and the hard, granular mass was collected,dried, powdered, and then extracted with a small quantity of benzene,which removed coloured impurities.The yield of this product, which consisted of the almost puresulphoxide, was 20 grams, or about 85 per cent. of the theoretical. Itwas finally crystallised from hot glacial acetic acid, from which itseparated in colourless prisms. The pure substance melts and decom-poses at 185' :0*1706 gave 0.3977 GO, and 0.0836 H,O.C,,HI,O,S requires C = 64-12 ; H = 5.34 per cent.It furnishes a bright blue solution with concentrated sulphuricacid, but does not then condense with phenolic ethers, as do othersulphoxides of this group.Some derivatives of t h i s sulphoxide have been previously investigatedby Mr.Hilditch and one of the present authors (Proc., 1907,23,161),and, together with others since examined, they are now described indetail.Dibenzoyl-p-cresol sulphoxide was obtained from the parent substanceby the action of benzoyl chloride in alkaline solution. It is solublein hot alcohol, and separates from that medium in colourless plates,melting at 173' :C = 63.6 ; H = 5.4.0.1375 gave 0.3591 CO, and 0.0593 H,O.VOL.XCVII. 7 HC=71-23; H=4*8,C,,H,,O,S requires C = 71.46 ; H = 4.68 per cent2250 GAZDAR AND SMILES : AROMATIC HYDROXY-SULPHOXIDES.Di-p-cresol XuZphide, (OH* C,H,Me),S.The sulphoxide was reduced by the action of zinc dust on the hotsolution in glacial acetic acid. On mixing the filtered solution withwater, the sulphide separated as a colourless oil, which slowly solidified.After being recry stallised from dilute acetic acid, di-p-cresol sulphidewas obtained in colourless needles, which melted at 143' :0.1900 gave 0-4735 CO, and 0.0984 H20.Previous experiments have shown that the sulphoxide which isformed (Smiles and Le Rossignol, Zoc. cit.) by the interaction ofthionyl chloride and p-tolyl methyl ether contains the quadrivalentbulphur group in the ortho-position with respect to methoxyl, andthere can be little doubt that the hydroxy-derivative, which isprepared in a similar manner from p-cresol, has the same constitution,namely :C = 67.97 ; H = 5.7.C14H1402S requires C = 68.29 j H = 5.68 per cent.Further and independent evidence in support of this structure willbe adduced in a subsequent communication, but a t present it may beobserved that this is borne out by the behaviour of the substance onnitration.It is extremely easily attacked by nitric acid, two nitro-groups being a t first inserted; but attempts to induce furthernitration by intensifying the conditions of reaction result in theelimination of the thionyl group with formation of dinitrocresol.The most favourable conditions for nitration are as follows :Nitric acid (2.7 C.C.of D 1.5) is gradually added to a cooled solutionof the sulphoxide (5 grams; about two-thirds OF the theoreticalamount) in glacial acetic acid (100 c.c.). After three to four minutesa large bulk of water is added. The precipitate is collected andboiled with alcohol to remove soluble impurities, and the insolubleresidue finally recry stallised.Nitro-p-cresol sdphoxide is soluble in hot glacial acetic acid, andvery sparingly so in boiling alcohol; it separates fiom the lattermedium in lemon-yellow prisms, which melt at 214'. The scarletsodizcm salt is readily soluble iu water :0.1718 gave 0.3009 CO, and 0.0545 H,O.Cl,Hl,0,N2S requires C = 47.73 j H = 3.41 per cent.Action, of Hydrochlovic Acid.-Five grams of nitro-p-cresol sulphoxidewere suspended in about 50 C.C.of alcohol, which had previously beensaturated with dry hydrogen chloride at the atmospheric temperature.The mixture was heated to 100' in a sealed tube for four to fiveC = 47.7 ; H = 3.8OAZDAR AND SMILES : AROMATIC HYDROXY-SULPHOXIDES. 2251hours. Finally, the solid product was collected, washed with alcohol,and then crystallised from hot glacial acetic acid, from which itseparated in long, orange needles. The weight of the crude substancewas almost equal to that of the sulphoxide employed. When pure itdid not contain halogen :0.1305 gave 0.2382 CO, and 0.0410 H,O. C= 49.78 ; H=3*5.0.1392 ,, 0.2532 CO, ,, 0 0490 H,O. C=49.6; H= 3.9.C,,H1206N,S requires C = 50-00 ; H = 3.5 per cent.The analytical data and the properties of the substance show that itis nitro-p-wesol sulphide. This compound melts at 194O, and is solublein hot alcohol aod insoluble in water ; the sodium salt is deep red incolour.Other sulphoxides, which are described in the following pages,have been treated in a similar manner, and similar reactions have beenobserved ; but with less highly substituted aromatic nuclei chlorinationoccurs, and even elimination of the sulphur may take place. It maybe recalled that other oxygen derivatives of quadrivalent sulphur,namely, the sulphinic acids, are similarly reduced by mineral acids.pChlwopheno I Xzclphoxide.The sulphination of p-chlorophenol was effected with thionyl chlorideunder conditions similar to those described i n the preparation of thep-cresol derivative.The crude product, which was obtained in a yieldof about 70 per cent. of the theoretical, was purified by precipitationwith dilute hydrochloric acid from an alcoholic solution. The substancemas finally crystallised from dilute alcohol, from which it separated insmall, colourless prisms. It melts a t 202O, and is sparingly soluble inether or hot water, and readily so in cold alcohol :0.1487 gave 0.2580 00, and 0.0366 H,O. C=47.33; H=2.73.0,3538 ,, 0.331 AgCl ,, 0*2'780 BaSO,. C1=23.2; S = 10-8.Cl,H,0,Cl2S requires C = 47.52 ; H = 2.73 ; C1= 23-43 ;S = 10.56 per cent.p-ChZorophenoZ sutphoxide is soluble in concentrated sulphuric acid,the kolution being at first colourless, but rapidly assuming a brightblue colour, which is slowly discharged by the addition of phenetole,indicating the formation of a sulphonium salt.Is will be shown in asubsequent communication that the thionyl group in this sulphoxideoccupies the ortho-position with respect to the two hydroxyl groups ofthe phenolic nuclei, the substance having the structure :/\OH HO/\ cljj--so--v I ICl.7 ~ 2252 GAZDAR AND SMILES : AROMATIC HYDROXY-SULPHOXIDES.p-Chloro&rophenol Xulphoxide.When submitted to the action of nitric acid, this chloro-sulphoxidebehaves like the similarly constituted p-cresol sulphoxide ; two nitro-groups are readily absorbed, but further action of the acid results indecomposition. The dinitro-derivative was prepared in the followingmanner.The sulphoxide was suspended in about thirty times its weightof cold glacial acetic acid, and while the mixture was stirred, exactlythe calculated amount of nitric acid (D 1.42) was added, Stirring wascontinued until almost all the finely-divided solid had dissolved, thenthe mixture was rapidly filtered, and the dark reddish-brown filtrateswere immediately poured into a large bulk of water. The precipitatewas collected and extracted with alcohol ; finally, the insoluble portionwas recrystallised in small quantities from hot glacial acetic acid, Inthis way, p-chloronitrophenol sulphoxide is obtained in fine yellowneedles, which melt at 180-181°. It is insoluble in cold waterand sparingly soluble in boiling alcohol :0.1740 gave 0.2342 CO, and 0.0341 H20.C=36.7; H=2-1.C,,H,07N,C1,S requires C = 36-64 ; H = 1-53 per cent.p-Chlorophenol Sutphide.The sulphide may be obtained by the action of hydrochloric acidon the sulphoxide in alcoholic solution under conditions similar tothose described in the preparation of the nitrocresol derivative. Toisolate the substance, the mixture was poured into water, and, aftersome hours had elapsed, the solid was collected and recrystallisedseveral times from benzene, when it mas obtained in colourless leaflstswhich melted at 173-174'. It was found difficult completely topurify this substance, since it tenaciously retained sulphides of higherchlorine content. For comparison, the sulphide was prepared by thereduction of the sulphoxide in the usual manner with zinc dust andboiling acetic acid, and the product, after recrystallisation frombenzene, melted sharply at 174O and contained the requisite amount ofhalogen :C1= 24.79.C,,H802C1,S requires C1= 24-71 per cent.0.1280 gave 0.1288 AgC1.When mixed with this substance, the product obtained by theformer method retained the same melting point.o-Chlorophenol Xulphoxide.Sulphination of o-chlorophenol was conducted as with p-cresol andpchlorophenol j the yield of crude sulphoxide was approximately thSOME PHENOLIC DERIVATIVES OF P-PHENYLETHYLAMINE.2253same as that recorded in these cases, The coloured impurities wereremoved by tritiiration with cold glacial acetic acid, then the insolublematerial was collected, and finally purified by recrystallisation fromdilute alcohol, to which a little hydrochloric acid had been added,o-Chlorophenol sulphoxide forms fine colourless needles, which melt at195", and are soluble in most hot organic media :0.1504 gave 0.2600 GO, and 0.0383 H20.0.1535 ,, 0.1415 AgCl.Cl=22*8.0,2032 ,, 0.1485 BaSO,. S = 10.0.C,,H,O,Cl,S requires C = 47.52 ; H = 2.73 ; C1= 23.4 ; S = 10.5 per cent.The substance dissolves in concentrated sulphuric acid, forming ablue solution, from which the colour is removed by the addition of aphenolic ether, a sulphonium base being then formed. The action ofalcoholic hydrogen chloride on this substance is somewhat differentfrom that observed in the preceding cases. After the usual treatment,the reaction mixture mas submitted to distillation in a current ofsteam. The white, crystalline solid which separated from the distillatewas evidently dichlorophenol, for it melted at 43O and contained 43.4'per cent. of chlorine (calc., C1=43.55 per cent.). The non-volatileportion consisted of an oil which resisted all attempts at purification;it apparently consisted of a mixture of polychloro-sulphides.C= 47.21 ; H= 2.83.I n conclusion, we desire to express our thanks to the Research FundCommiftee of the Chemical Society for a grant which has defrayed theexpenses of these experiments.ORaANIC CHEMISTRY LABORATORY,UNIVERSITY COLLEGE, LONDON