1546 LAPWORTH AND KIPPING : C I I.-Dei-ivati rcs of Ca mphene-su7phonic acids. By AR'rHUR LAPWORTH, D.Sc., and FREDERIC STANLEY KIPPING, Ph.D., D.Sc. AMONG the many changes which camphor undergoes, one of the most interesting is its conversion into acetylortho-xylene [2Me : Ao = 1 : 2 : 41 by concentrated sulphuric acid ; aud, although this reaction may be expressed by the simple equation CioHiGO + 2 0 = CioHiZO + 2H20, there can be no doubt that the change is a very complex one, and that oxidation is accompanied by a profound molecular rearrange- ment. Partly in the hope of obtaining some product, the study of which might throw light on this curious reaction, and partly in order to t r y to obtain sulphonic derivatives of camphor, an investigation of the behaviour of camphor towards sulphuric acid under various con- ditions was commenced several years ago, and it was then ascertained that camphor is vigorously attacked by anhydrosulphuric acid at ordinary temperatures, giving, amongst other products, a mixture of optically isomeric camphorsulphonic acids (Trans., 1893, 63, 548).The isolation of these compounds directly from the crnde product being impracticable, i t was necessary, in the first place, to convert uhe acids into the corresponding sulplionic chlorides by treating t'he mixture of sodium salts with phosphorus pentachloride in the usual manner. Dextrorotatory camph orsulphonic chloride and nn optically illactive modification of this compound, were then separated in a crystalline condition from the oily product thus obtained, but a veryDERIVATIVES OF CAMPHENE-SVLPHONIC ACIDS.1547 considerable proportion of the prodnct refused to crystallisc, and was not further investigated at the time. The probability that the constituents of this residue might be derived from intermediate products in the conversion of camphor into acetylortho-xylene, or from substances resulting from the partial breakdown of camphoy, has induced us to take up the examination oE this oil again, in spite of its uninviting character ; it is a record of this work whicb. we now communicate. The original oily mixture of sulphonic chlorides, prepared from the crude prodnct of the sulphonation of camphor in the mannei' previously described (Zoc. cit., pp. 549-552), contains, and apparently consists en tirelg of, four well-defined, crystalline compounds-namely, the dex trorotatory and optically inactive carnphorsulphonic chlorides which were formerly kolated, and two optically inactive sulphonic chlorides of the composition CloHl4C1*SO2C1, which we propose to name u- and p-chlorocampheneszLl~~~nic chloride rcspectively.These names are assigned to the two optically inactive isomerides mainly because their molecular composition indicates that they are derived from a chlorocamphene, and because the conditions under which they are formed froin camphor are, doubtless, such as might a t the same time bricg about the transformation of camphor into chlorocamphene. When camphor is submitted to the action of phosphorus pentachloride, it gives, as is well known, a dichloride cf the composition C,,H,,C12, which is changed to camphcne by the action of sodium on its ethereal solution; if, however, this dichloride be heated alone, or with quinoline (Marsh and Gardner, Proc., 1894, 57), it loses the elements of bydrogen chloride, and is converted into chlorocam phcne.It seemed very probable, therefore, t>hat the action of excess of phosphorus pentachloride c n the sodium salt of camphorsulphonic acid might bring about not mcrely the formation of the sulphonic chloride in a normal manner, butl also tbat of an unstable dichIoro- sulphonic chloride, which might then lose the elements of hydrogen chloride. NaO+332-C,H,,<?H2+ Cl-S0,~C,Hl,<~H2 - Cl-SO,~C,H,,< CH i I co c c1, cc1' A compound formed in t'his way from an optically inactive 01- racemic camphorsulphonic acid, by reactions analogous to those which are known to occur in the case of camphor, would have the composi- tion of the isomeric sulphonic chlorides in question, and would be derived from EL chlorocamphene identical or isomeric with thak referred to above ; the names which we have given to the two new compounds seem, therefore, to be appropriate.The fact that two isomeric, optically inactive chlorocamphexie-1548 LA PKORTH AND RIPPING : sulphonic chlorides are obtained under the above conditions is capable of several interpretations, but, in absence of facts, little would be p i n e d by discussing the relation between the iwo. The study of the properties of the two isonierides confirms the vicw that they arc derivatives of camphenc ; having fully established their coinposition by the preparation and analysis of the correspond- ing amides, we made attempts to oxidise or otherwise break clown some of the various componnds.These experiments, however, were a11 unsuccessful owing to the great stability of the substances, in which respect they show a marked relation to camphene, and behave, indeed, as might be expected of camphcne derivatives. In r;pite of the lack of success which has just been mentioned, several interesting facts have been established during the inrestiga- tion. Thus a-chlorocamphenesulphonic chloride exists in t RO definite physical modifications, both of which have been examined crystallographically, arid differ in melting point by only 4'; the melting point of the P-sulphonic chloride is the same as that of one of the modifications of the a-compound, but the crystals a.re not suitable for goniometrical measurement.Both compounds are so slowly hydrolysed by hoiling water, and are so readily volatile, that they may be distilled in a current of steqni without any very large qumtit-y being decomposed--n behaviour rarely met with in the case of sulphonic chlorides generally ; even more remarkable, however, is the fact that the decomposition of the a-compound by water at moderately high temperatures yields not only the corresponding u-chlorocan~phenesulp~onic acid, CloHliCl*S03H, by interaction with water in the normal manner, but also a dichlorocnmphene, which is formed in accordance with the equation C,oH,,CI*SO2Cl = CI,,HI,CI, + SO?.The latter change occurs almost quantitatively when the sulphonk chloride is heated with water at EO', and is, we believe, the first case in which such a decomFosition has been observed undcr the given conditions. a-Dichlcrocamphene is also formed when the a-sulphonic chloride is heated alone at 160-1€0', a behaviour which is analogons to that of many of the sulphonic chlorides and bromides of camphor, and which seems to be especially characteristic of snlphonic derivatives containing the group -CH,*S02X (X = C1 or Br). a-Dichloro- camphene is chiefly remarkable on account of its great stability ; i t crysiallises in needles and is very volatile, its vapours having a strong, rather pleasant, smell. 6-C hlorocamphenesnlphonic chloride is hydrolysed by boiling water, but only extremely slowly; the action in t h i s case takes the ordinaryDERIVATIVES OF CAMPHENE-SULPHOKIC ACIDS. 1549 course, the corresponding sulphonic acid being formed.Tbo decom- position which the P-sulphonic chloride undergoes when heated alone seems, however, to bc analogous to that of the a-compound, inas- much as sulphur dioxide is evolved, and a volatile, neutral oil is produced ; as a considerable qnantity of tarry matter is also formed, and the yield of P-dichlorocamphene is comparatively poor, we did not prepare the latter in quantity sufficient for a thcrough examination. ~ - C h l o r o c a ~ n ~ h e n e s u ~ ~ o ~ i c acid, CloH14C1*S03H, which, like the isomeric a-cornpound, shows all the ordinary properties of substances of this class, undergoes a curious intramolecular change when it is warmed with mineral acids, being transformed into a neutral snb- stance insoluble in water ; the nature of this isomeride has not been definitely established, but it seems probable that it is a SdphoZnctone, C,,H,,CI<i> , derived from a saturated hydrocarbon (cnmnphan) of the composition CloH18.It is well known that certain unsaturated acids of the type >C:CH*[CH,],,-COOH (n = 1 o r 2) are converted into saturated lactones of the type >C*CH,*CH,*YO I o r >CH*CH*CH,.CH,*$lO by intramolecular change, either on distillation or under the influence of mineral acids, and, as p-chlorocamphenesulphonic acid probably con- tains an unsaturated group, >C:&[$].*CH,-SO,H ; i t seems likely that a similar intramolecular change may occur, a lactone containing the complex >CH*&*[hln*CH2*SO2 I being formed.s 0 2 I 0 1 0 I-.-- 0 The properties of the neutral substance are conformable with this view of its character, and, therefore, for the sake of reference we name the compound ~-shlorocanipl~ansulpliolactone. EXPERIMENTAL PART. The yellow oil, obtained by the action of phosphorus pentachloride on the mixture of sodium salts of the sulphonic acids produced by the sulphonation of camphor, constituted the raw material for this investigation. This oil is repeatedly extracted with light petr- oleum, atl first a t ordinary temperatures with petroleum boiling at 20-30°, and subsequently at higher and higher temperaturas with various fractions of petroleum boiling a t temperatures rising to about llOo.Iu this way a very rough separation of the four con- stituents of the mixture is effected ; the camphorsnlphonic chlorides, particularly the optically active modification, ara, when purified, much more sparingly soluble than the chlorocamphene derivatives,1550 LAPWORTH AND KIPPING : mid are, therefore, contained in the later extracts, froni which they are deposited in a crystalline condition, almost entirely free from the more soluble camphene compounds. The solutions, from which the crystals of camphorsuIphonic chlorides have been separated, yield, on spontaneous evaporation, first, fnrthev quantities of crys tallinc materia1, and then a deposit of a yellow oil ; the crystalline products, consisting of mixtures of varying proportions of sulphonic chlorides of camphor and of chlorocamphene, vary considerably in character ; they are collected in such a way that those of similar appearance are brought together.The yellow oil, deposited from the later extracts, is then fractionally extracted with petroleum in the same way as before, and is thus separated into one or two crystalline por- tions (which are added t o those of similar appeamnce already obtained), and a portion which remains liquid. These liquid portions are mixed with the large deposits of oil which separate (dmost free from crystals) from the first extracts of the original crude prodnct, and the whole is ngnin systematically extractcd as before until the solutions cease to yield any crystalline material when left undis- turbed for a few days.The various petroleum solutions are then allowed to evaporate, and the oily residues placed aside in a cool place ; during the minter months the oils gradually solidify, and the crystalline material is then separated with the aid of the filter pump, and spread on porous porcelain. I n this way practically the whole of t h e original product is eventually obtained in a crystalline condition. The final separation of the four sulphonic chlorides is accomplished by taking the various crystalline fractions which have been collected, and submitting them to fractional crystallisation from light petr- oleum ; a detailed description of this tedious and troublesome process would not be of rery much yalue, because the operator must judge more from the appearance and melting-point of each deposit than from its mere solubility. It may be noted, however, that various fractions of light petroleum (b.p. 20--30°, 40-50°, and 70-80") must be used in order to effect the desired separation ; further, that, although the purified comphor.;dphonic chlorides are much mere sparingly soluble than the camphene compounds, they are frequently met with in the most soluble fractions, even after repeated crystalli- sation. As soon as the camphor compounds have been to a great, extent freed from the chlorocamphene derivatires, a little ether added to the petroleum aids the final separation ; fhera is, in fact, very little difficulty in isolating the camphorsnlphonic chlorides, but the separation of the two camphene compounds is much more troublesome, partly owing to their being frequently deposited in an oily state, especially in presence of a trace of camphorsulphonic chloride, partly owing to their great solubility in the only solvent which can well be used. Finally,DERIVATIVES OF CAMPHENE-SULPHONIC ACIDS.15 31 however, two main fractions are obtained, one being the a-compound in the form of small nodular crystals melting at about 84', the other, the isomeride, in large, transparent plates melting at about 75'. The former is practically pure ; the latter, however, cannot apparently be obtained from petroleum in a pure state, and must, therefore, be purified by one or two crystallisations from methylic alcohol, whereby it is obtained in long, transparent needles, which melt at practically thc same temperature as the massive crystals of the a-compound, namely, at 83-84". a- Chlorocam23ltenesulphonic Chloride, CloH14C1*S02Cl.a-Chlorocamphenesulphonic chloride is one of the principal COE- stituents of the original crude oil, whereas the @-compound is present in comparatively small quantities. Having been separated in the manner already described, it may be further purified by a final crystallisation from a mixture of benzene and petroleum. A specimen prepared in this manner, and melting at 83-84', was analysed witth the following result : C = 45.23 ; H = 5-38. 0.1759 gave 0.2919 CO, and 0.0852 H,O. CloH14C1*S02Cl requires C = 44.7; H = 5.2 per cent. a-C blorocamphenesulphonic chloride separates from cold, light petroleum, chloroform, o r benzene, in the form of beautiful trans- pnrcnt crystals, which melt at 83-84"; if fused and allowed to solidify, it melts at 87-88", a probable indication of dimorphism.It is extremely soluble in benzene, chloroform, acetic acid, sthylic acetate, acetone, and ether, and it dissolves very readily also in hot,, light petroleurn (b. p. = 60-70'), but is much less soluble in the cold liquid ; in methylic alcohol it is somewhat sparingly solnhle, being dissolved rather freely by the hot liquid, but separating, for the most part, as the solution cools. When heated with water, i t sinks as an oil, but a small quantity passes into solution ; on cooling, i t is first deposited as an oil, finally separating in the form of long, semi-transparent needles ; it maly be boiled with water during several days without undergoing hydrolysis to any considerable extent.I t rolatilises to some extent in aqueous vapour, and, when very impure, may be obtained in a crystalline state by subjecting it to distillation in steam; at the same time, however, a minute amount undergoes decomposition into sulphur dioxide and dichlorocamphene. When heated with water in sealed tubes a t 120', it is almost entirely con- verted into dichlorocamphene. It is very rapidly hjdrolysed when heated with solutions of soluble metallic hydroxides, a metallic chloride and a chlorocamphenesnlphonate being produced. a-Chlorocamphenesnlp honic chloride, like t,he sulphonic chloride of a-bromocamphor, is exceedingly stable towards ordinary oxidising1552 LAPWORTII AND KIPPING : agents; i t may be boiled with nitric acid (sp.gr. = 1.4) during several minutes, and be subsequently recorered practically unchanged. When boiled with fuming nitric acicl, however, i t is slowly acted on, nitrous fumes and chlorine being evolved, whilst a marked oclour of chloropicrin is perceptible ; after several hours boiiing, the action becomes distinctly less rapid, and if the liquid at this point be diIuted and evaporated on the water bath, precaution being taken to get rid of all nitric and sulphuric acids, the oily mixture on dilution deposits a srriall quantity of a substance insoluble in water ; but the oils, how- ever treated, do not evince the slightest tendency to crystallise ; they consist, doubtless, of snlphonic acids, as very little sulphuric acid is formed during the oxidation, and i t is probable that the substance insoluble in water is a sulpholactone analogous to that obtained by us on oxidising ammonium bromocamphorsulphonate with nitric acid (Proc., 1896, 77).I n the hope of obtaining derivatires of the sulphonic chloride con- taining more halogen, we have investigated the action of bromine on the compound. On mixing a solution of the chloride in chloroform with bromine, it is coloured yellow, but the colour gradually dis- appears, hyqrogen bromide being evolved. The liquid, on evaporation, deposits a colourless oil, from which we have not succeeded in obtain- ing any crystalline matter. Similar experimeuts made with solutions of the substance in petroleum and ether proved equally fruitless.The crystallographic properties of a-chlorocamphenea ulp honic chloride were carefully studied, the behavioor, on fusion, of the crystals deposited from petroleum, &c., having indicated that the substance is dimorphons. Repeated endeavours were made to isolate the two modifications by crystallising the substance from various solrents under diverse conditions, and it was thus discovered that, although in almost every case the crystais obtained belonged to the anorthic system, and melted at 83-84", yet when crystallised from hot methylic alcohol the chloride separated in comparatively simple crystals, obviously different in type from those obtained in other wajs. They were of orthorhornbic sjmmetry, and melted at 87--8S0. The t w o forms were submitted to a somewhat detailed examination, and the following data were obtained.The first modification, melting at 83-84", is deposited from solu- tions of the sulphonic chloride in acetone, ethylic ace Me, ether, benzene, chloroform, light petroleum, or cold methylic alcohol. Crystals obtained from petroleum or chloroform consist of magnifi- cent, transparent, anorthic prisms with a calcite-like lustre ; t,hose from cold meihylic alcohol form plates, which, although they bear no obvious resemblance to the foregoing, j e t are found, on measure- ment, to bc derived from the same forms.DERIfhTIVES OF CAMPHENE-SCJLPHONIC ACIDS. 1553 Crystalline System : Anorthic. u : b : c = 0.6668 : 1 : 0.8396. a = 79" 46', p = 96" 32', "1 = 88" 5'. Forms observed : a ( i ~ ~ ) , b(oio), c(ooi), ppio), q(o2i), o ( l i i ) , or(iii.).F I G . 1. FIQ. 2. The following angular measurements were obtaiued : No. of Angle. measurements. Limits. Mean. Calculatcd. 26 41" 19'- 41' 59' 41' 48' - np = 100 : 110 QO = 100: iii oto = 111 : 111 19 '73 24- '74 32 73 67 73 53 = Iii : 100 48 34 - 18 48 46- 49 35 49 13 - 18 56 26- 57 29 56 59 - ph = 110: 010 26 43 10- 48 51 ba = 010: loo 24 89 4- 90 5 89 38 89" 38' ac = 100: 001 4 69 13- 70 8 69 41 69 51.5 cp = loo: 110 12 81 0- 81 58 81 34 81 30 = ooi : ioo 4 110 22-110 45 110 34 110 8 . 5 43 26 - 130 = 3.19: 111 14 45 57- 49 51 oc = iii: OOI 12 48 28- 49 32 49 10 49 4 C d - 001 : I1I 4 125 39-126 11 125 5& 125 57 otC = iii : ooi 4 53 42- 54 a 53 54 54 3 bo = 010 : I1I 4 75 43- 76 36 76 16 76 4 ho' = 010 : ili 7 73 50- 74 46 74 10 74 3.5 bp = 010: 021 3 43 35- 44 23 44 0 43 41 = iii : 010 4 103 31-104 1 103 44 103 56 o'b = iii : oio 7 105 23-106 12 10.5 50 105 56.5 cL = 001 : 010 8 69 13- 70 8 69 48 69 51 qc = 021 : ooi 3 65 59- 65 52 66 35 66 25 pq = 110: OZI 6 5'7 25- 57 59 57 41 57 31 qof = 021 : iii 8 45 13- 45 53 45 31 45 31 otP = iiI : i i o 8 76 29- $7 2 76 54 76 58 The crystals obtained from solutions of the sulphonic chloride in chloroform or petroleum crystallise in the more massive habit depicted1554 LAPWORTH AND KIPPING : in Fig.1, whilst those cbtained from cold metbylic alcohol assume the plate-like form of Fig. 2. The measurements obtained from the former were not so concordant as those from the latter, owing to the sub- stance being more readily soluble in chloroform and benzene than in methylic alcohol, re-solution, therefore, taking place more freely i n the former instance.In the prismatic crystals (Fig. l), the forms n(100), b(010), and c(OO1) are most strongly developed, the last- mentioned being almost invariably the largeut on the crystal ; the form a( 100) is usually corroded, and gives exceedingly poor images ; m{111) and o(I11) are usually discernible and give good reflections, whilst q(O2l) has been noticed only on two crystals, one face of the form being present in both cases. In the plate-like crystals, the predominating form is p(llO), which is always bright and gives excellent images; of the other forms b(010) and q(O%) are always present, whilst the pinncoid ~(001) occurs but seldom, and, as in the case of the prismatic crystals, is usually deeply corroded. There does not appear to be any definite cleavage, although slices may occasionally be separated approximately parallel to the three pinacoiids a(100), b(010), and ci001).The acute optic axial bisectrix appears t o emerge somewhere in the angle between b(010) and p(110), but owing to the brittle nature of the crystals the orientation of the axial plane could not be determined with any certainty. The axial angle is wide ; the double refraction is rather strong and negative in sign. The dispersion is strong. The second modification of a-chlorocamphenesulplionic chloride is obtained when the modification just described is melted and allowed to cool. It is also obtained, as has already been mentioned, when the sulphonic chloride is crystallised from hot methylic alcohol, and then forms brilliant, transparent tables or pyramids, which melt at 87-89', and remelt at the same temperature, When allowed to remain, eithci- in the solvent or in the open air, they are seen to develop white patches, which are sharply defined from the transparent portion ; these patches, in a few days, extend through the whole mass of the crystal, renderiag it quite opaque, and the crystal then melts at 83-84', thus showing that the opacity is caused by a reversion of the substance or the crystal to the first or anorthic modification. The crystals lend themselves very well to goniometrical examina- lion, and thc following are the results which have bcen thus obtained : Crystalline System : Orthorhombic.a : b : c = 0.9030 : 1 : 0.9358. Forms observed : a{100), b(010), ~(lll), and ~ ( 1 1 0 ) .DERIVATIVES OF CAMPHENE-SULPHONIC ACIDS. 1 555 FIG. 3, Thc following angular measurements mere obtained : No. of Angle. observations. Limits. Mean. t o 2- 010 : 111 32 56’ 45’- 5i0 10’ 56” 59’ 00 = 111 : 111 1G 65 51- 66 28 66 4 PO = 110: 111 20 35 15- 35 54 35 37 00 = 111 : 111 1 G 108 29-109 19 108 45 t r = 110: 010 25 47 46- 47 67 47 50 ~rp = 100: 110 22 4L 54- 43 17 42 8 00 = 100 : 111 6 52 40- 53 3 52 54 PO = 111 : iii 4 74 1 - 74 26 74 9 bn = 010 : 100 16 89 49- 93 7 93 2 ob = 100: oio 16 89 51- 90 7 89 57 Calculated. 66” 2’ 108 4G 47 55 42 5 52 54 74 13 90 0 90 0 - - The crystals, as a rule, are unsymmetrically developed tables or pyramids, with brilliant faces ; the latter yield fairly good images, even when the crystals have become quite opaque owing to rever- sion to the anorthic modification.The form o(ll1) is usually the largest, but is sometimes reduced t o a mere strip; in the latter instance, t( 0101, usually small, becomes the predominating form ; a(100)) is invariably small, but yields perfect images, as do the forms ~(110) and b(010). The reflect’ions from o ( l l 1 ) are rather poor. There is no definite cleavage. The acute bisectrix emerges parallel to the axis 6, the optic axial plane being c(OG1). The double refraction is positive and fairly strong, the optic axial angle being rather wide. The dispersion is slight. a- Clr. iorocamphenesulphonamide, CloE14C1.S0,*NL12.I n order to prepare the amide, the sulphonic chloride is finely powdered and added to about 10 times its weight of strong aqueous ammonia containcd in a stoppered bottle, and the whole vigorously shaken ; after a short time the powder seems to suddenly change in crystalline form, becoming much mcwe bulky, but no development o€ heat is noticeable. At the end oE about four hours, the liquid and1556 LAPWORTH AND KIPPING : crystals are transferred to an evaporating basin, the ammonia allowed to evaporate, and the crystals separated and washed with cold water; the residue is finally crystallised from dilute alcohol and dried at 100'. 0.1669 gave 0.2975 CO, and 0.1015 H,O. C = 48.6; H = 6.76. 0.1593 ,, 0.2817 ,, ,, 0.0955 ,, C = 48.2 ; H = 6.66.C,oH14Cl*S02*NH2 requires C = 49-12 ; H = 6-43 per cent. a-Chlorocamphenesulphonnmide is readily soluble in alcohol, ether, acetone, and ethylic acetate, somewhat less readily in cold benzene, and only sparingly in chloroform, petrolenm, and water. It is dis- solved by dilute alkalis, and is reprxipitated on the addition of acids. It crystallises from nearly all solvents in thin plates with a satiny liistre, but from its solution in chlomform i t is precipitated by light petrolenm in the form of feathery, skeleton-like forms. It is probable that this subst.ance is dimorphous, as on one occasion i t was found to fuse sharply at aboutl 135O, and then to solidify imme- diately, melting once more at 161--162O, its usual melting point ; after solidifying, it melts at the latter temperature.The crystals deposited from the alcoholic solution on spontaneous eraporat ion are small rhomboidal plates truncated at their acute a,ngle. The extinctions in polarised light bisect the angles of the rhomb, and under convergent polarised light the large face of the crystal is seen to be perpendicular to an optical bisectrix, probably the acute. The crystals are therefore orthorhombic, the large face being a pinacoid (100) cut off by the four faces of the dome (0111, which make an angle of about 79" with one another, and are trun- cated at the acute angle by the form (001). When melted upon a microscope slide under a cover glass, the amide solidities in arbore- scent forms, which lie perpendicular to the bisectrix seen in the crys- tals above mentioned.The axial mgle is large, the doubIe refraction being very weak and positive in sign. Hoping to obtain the corresponding derivatives of camplrene by the reduction of chlorocamphenesulphonic acid derivatives, and regarding the amide as the most suitable compound with which to experiment, we have closely examined its behaviour towards reducing agents, but without success. It is not changed when its alkaline solu- tion is heated during several days with a large excess of sodium amalgam; it also resists the actionof zinc dust and ammonia at looo. The stability of the chlorine atom in presence oE alkalis is also very remarkable ; the amide, when heated for several hours with boiling strong soda-lye prepared from the metal, does not gire a detectable quantity of sodium chloride.The dispersion is slight.DERIVATIVES OF CAMPHENE-SULPEONIC ACIDS. 15.57 a- Chlorocampheneszl~hanilide, C,oR,,C1*SO,*NH.C,H,. When a-chlorocamphenesulphonic chloride is heated with aniline for a, short time on the water bath, it gives a dark browu product, from which it is somewhat difficult to isolate the anilide. If, haw- ever, the sulphonic chloride and aniline are dissolved together in ether, and the solution is allowed to remain in a stoppered bottle during three or four days, aniline hydrochloride is deposited in con- siderable amouut, and only a slight discoloration ensues. The anilidc is easily obtained h o r n the praduct by evaporating the et.her at ordinary temperatures, washing the residue with dilute hydrochloric acid and water successively, and then crystallking i t twice from dilute alcohol.An analysis of this compound was deemed unneccs- sarg, but it was proved to contaiu chlorine by qualitative tests. a-Chlorocamphenesulphanilide dissolves readily in alcohol, ethy lic acetate, arid acetone, but is rather less soluble in ether and chloro- form, and dissolves only with difficulty in benzene ; it appears to be insoluble in light petroleum and i n water. When slowly heated, it, begins to darken a t about 810°, arid melts at 234", but when the capillary tube is plunged into sulphuric acid at 2 3 4 O , the anilide remains solid up to about 237'. It crystallises from hot methylic alcohol in long, beautiful, colour- less, striated plates, their ends being obliquely truncated at about 45O ; they probably belong t o the anorthic system.When examined i n polarised light, the errtinctions make angles oE abont 5 5 O with the sides of the plate. Examined under a 2%'' immersion objective iu convergent polarised light, an optic axis is seen to emerge at the edge of t,he field, corresponding with the direction of greatest Icngth. of the crystal ; the double refraction is weak. a- Ch lorocamphenes.ltl~)?honic acid, C,oH,,Cl*S 0,H. As has already been mentioned, a-chlorocamphenesulphonic chloride exhibits great stability towards boiling water, and even after boiling with a large excess of water during a week only a small proportion undergoes hydrolysis ; decomposition may be hastenkd by carrying out the process in sealed tubes in toluene vapour, but under these conditions a large quantity of dichloro- camphena is formed.The best way to prepare the acid is to heat the sulphonic chloride with SL solution of barium hydroxide, lvhich produces almost instantanems hydrolysis without causing the re- moval of the second chlorine atom ; the barium in solution is then precipitated by the careful addition of sulphuric acid, and the filtered solution of the sulphonic acid is repeatedly evaporated until free from hydrochloric acid. VOL. LXIX. 5 N1558 LAPWORTH AND KIPPLNGI : When the syrup finally obtained is kept in a desiccator, it grada- ally sets t o a mass of thin plates, which appear t o contain water of crystallisation ; after hrtring been sprenl on porous earthenware oyer sulphuric acid and then dried at 100' until constant in weight,, i t may be further purified by crystallisation from hot benzene, from which i t is deposited in small plates.a- Chlorocamphenesulphonic acid dissolves very readily in water and alcohol, and is also somewhat readily soluble i n ethylic acetate, acetone, chloroform, and hot benzene ; it dissolves somewhat sparingly in ether, and appears t o be quits insoluble in light petro- leum. Its aqueous solution has a bitter, somewhat astringant, taste, and dissolves zinc readily, evolving hydrogen. When the anhydrous acid is slowiy heated, it gradually becomes dark brown, and a t 264-265' swells up considerably, evolving gases, amongst which sulphurous nnhFdride is perceptible by its odour, finally forming a fairly limpid liquid. The crystals deposited from hot benzene are beau- tiful, small, elongated, glistening plates of ill-defined outline ; on examination in polarised light, they usually show very brilliant interference colours, and, in convergent light, some individuals show an optic axis emerging perpendicularly. The optic axial angle is fairly large, and the double refraction is strong whilst the dispersion is rather slight.The following metallic salts of the acid were prepared from the latter by neutralising its aqueous solution with the corresponding me taliic carbonates. Potassium a-cli ~oroca~nphe,aesulpholzate crystallises from water in .small, well-defined, elongated, orthorhombic prisms showing the forms (loo), (LIO), and (111). The small size of the crystals made it impossible to determine their optical properties.The subst,ance dissolves readily in water, and is precipitated by strong potash, it is nearly insoluble in acetone and in strong alcohol. Sodium a-chZorocamphenesulphonate crystallises from hot water in ill-defined plates, but is obtained in well-defined pyramidal crystals on allowing the aqueous solution to evaporate spontaneously. It is insoluble in acetone, but dissolves slightly in strong alcohol. The double refraction is very weak. Attempts were made to cause the separation of the sulphonic group from a-chlorocamphenesulphonic acid by heating it a t high temperatnreu with hydrochloric or sulphuric acid. In every case it was found that, where partial hydrolysis had occurred, the prodnct had at once carbonised, and nothing but unaltered acid and a charcoal- like mass could be obtained.DERIVATIVES OF CAMPHENE-SULPROXIC ACIDS.1559 a-Dichhrocamphene, C,,K,,CI,. The study of the decomposition products of the sulphonic chlorides and bromides of camphor derivatives, more especially in the case of ar-dibromocamphor, having yielded such interesting results, the effect of heating a-chlorocamphenesulphonic chloride was carefully investigated in the hope of eliminating sulphurous anhydride, and thus obtaining a dichlorocamphene which might serve as the start- ing point for further experiments. It was found that a-chlorocamphenesulphonic chloride does, in fact, undergo decomposition at elevated temperatures, and that the change is analogous t o that which occurs in the case of the camphor derivatives p~eviously studied, the products being cc-dichlorocam- phene and sulphur dioxide a-Dichlorocamphene may be prepared by simply distilling the puri- fied camphenesulphonic chloride, but, as the distillate is usually con- faminated with unaltered snlphonic chloride it is better to keep the temperature at 160--180° until the evolution of sulphur dioxide is at an end ; the brownish liquid residue is then distilled, and the crys- talline product purified by crystallisation from alcohol.A less impure product is obtained if t.he sulphonic chloride is heated at a temperature of 130-140°, with about five times its weight of water, for about 48 hours. Although, under these con- ditions a small quantity of tho snlphonic chloride is converted into the sulphonic acid, yet the greater part suffers the above-described decomposition, and the a-dichlorocamphene, after distillation with steam, is obtained practically free from impurity.A sample which had been recrystallised from alcohol and dried over sulphuric acid gave the following results on analysis : 0.1495 gave 0.3212 CO, and 0.0959 H20. C = 58-59; H = 7-13. 0.1956 ,, 0.2710 AgC1. C1 = 34.2. C~,,HlaC12 requires C = 58.61; H = 6.84; C1 = 34.67 per cent. a-Dichlorocamphene is excessively soluble in light petrdleum, benzene, ethylic acetate and acetone, but less readily in methylic and ethylic alcohols, and nearly insoluble in water. I t is deposited from a cold solution in rnethylic alcahol as beautiful, t.raasparent needles or prisms, whose sides are composed of lustrous faces, but whose terminations appear as if broken off, so that their gonio- metrical examination was useless ; from dilute alcohol it crystallises in curious fern-like forms which are made up of aggregations of fine needles. It melts at 72-73', sublimes readily when heated alone, 5 ~ 21560 LAPWORTH AND KlPPING : and is excesaively volatile in aqueous vapour ; its odour is remark- ably powerful, and i s reminiscent of fresh india-rubber.When a solution of a-dichlorocamphene in acetic acid is heated with a large exce.w of zinc dust, frae from halogen, it appears to snffer decomposition, as, after d.lution and filtration, the solution gives a distinct precipitate with silver nitrate; the quantity 80 reduced, however, must b3 very small, as the substance precipitated G n dilntion melts only a few degrees below the melting point of the pure compound, and is easily shown to be unaltered dichlorocam- phene.All other attempts to effect its reduction proved equally futile. The substancs in acetic a2id solution does not appear t o be oxi- dised by cold potassium psrmanganate, and when heated with aqueous oxidising agentq, such as nitric acid, i t sublimes almost im- mediately, thus escaping oxidation ; in all respwts it was found to be an extremely stable substance, and for these reasons its study was n ~ t carried farther, p- Ch lorocamphmesulpho,z ic Chloride, CIoHI,Cl.S 0,Cl. The impure /3-chlorocamphenesulpEonic chloride (m. p. abou t 75'1, separated from its isomeride in the manner already described, was purified by repeated crystallisation from light petroleum (b.p. 30- 40°), and was thus obtaified in large plates melting a t 77-7s"; as this preparation seemed to be homogeneous, and its melting point did not alter on further crystallisation from light petroleum, a sample mas analysed, with the following resuIts. 0,1532 gave 0.2529 CO, and OsOS20 H,O. C,oH,4Cl*SOzC1 requires C = 49-66 ; H = 5 21 per cent. Although this analysis, no doubt, correctly represents the composi- tion of the substance, all specimens purified in the above manner are still slightly impure, an3 the melting point given in the preliminary notice (77-78') u-as on this account somewhat too low, since, by using a solvent such as metbylic alcohol, in which the two chlorides are more nearly equally solubk, the meltiug point of the ,+suIphonic chlolide may be finally raised to 83-84', which is the same as that of the ordinary form of the a-sulphonic chloride.P-C hlorocamphenesulphonic chloride does not appear to be dimorph- ous like the a-compound, although i t assumes two habits entirely dit€erent in appearance ; from light petroleum it is deposited in large, transparent plates, which become white and opaque on exposure to the air, or when gently heated in contact with the supernatant solution ; fwm hot mzthylic alcaliol it crystsllises in beautiful, long, trans- paraat needles, which completely traverse the mother liquor, being C = 45.02 ; H = 5 94.DERIVATIVES OF CAMPHENE-SULPHONIC ACIDS. I 561 usually terminated only by the Fides of the containing vessel. These needles belong to the tetragonal system ; a thin transverse section of one of them, when observed i n convergent polarised light, is found ta be perpendicular to the optic axis of a uniaxial figure ; the same appearance is observed when a small quantity of the substance is allowed to solidify between glass plates, when the compound crystal- iises in fern-like forms, whose appearance is indistinguishable from ammonium chloride, all the branches making 90" with one another.The double refraction is strong and positive in sign. P-Chlorocnmphenesulphonic chloride is much more freely soluble in most solvents than its isomeiide, liquids, such as benzene, chloro- form, and ethylic acetate, dissolving it to an almost indefinite extent ; it is also readily soluble in cold light petroleum (b.p. = 25-4OO). As indicated above, however, it is somewhat sparingly soluble in cold methylic alcohol. It shows much the same stability as its isomeride towards various agents. It is scarcely affected by boiling water, and may be boiled with it during several days without undergoing much decomposition, but is almost instantaneously hydrolysed by boiling solutions of metallic hydroxides, yielding the corresponding sulphonates. It is readily volatile i n steam, and this fact may be taken advantage of i i i effecting the crystallisation of the lasb portions of crude oils, which contain large qaantities of the P-sulphonic chloride. It is slowly acted on by a solution of bromine in chloroform, but the product, as in the case of the isomeric chloride, is not readily purified, and has not yielded a trace of crystalline matter.Its beha- viour towards nitric acid also resembles that of its isorneride; the oxidation product, after elimination of nitric acid, yielded a small quantity of a colonrless substance, insoluble in water, but soluble in acetic acid, probably a sulpholactone, together with a large quantity of rion-crystalline matter, doubtless consisting of a mixture of snl- phonic acids. /3- Ch lorocamphenesuZpho)iamide, CloHlrC1*S02*NR2. This compound is prepared by treating the sulphonic chloride with cold aqueous ammonia in the usual wanner, and is readily purified by crystallisation from metbjlic alcohol, A specimen F'BS dried at loo3 and analysed. C = 48-11 ; H = 6.68. O.li12 gave 0.3020 GO, and 0.1014 H20.C oH14C1*S0zNH2 requires C = 48.12 ; H = 6.42 per cent. f3-Chlorocamphenesnlphonamide crystallises from cold alcohol or et hplicsacetate in curious, ill-defined, striated plates, which melt at 156-157" It differs considerably from its isomeride in regard t o its1562 LAPWORTH AND 3IPPlNG : solubility in various liquids; tbus, whilst the latter is only sparingly soluble in chloroform, the former dissolves readily ; the a-derivative appears to be insoluble in petroleum, whilst tthe &derivative is appx- ciably soluble. On adding petroleum to hot solutions of the two amides in chloroform, crystals are deposited, which are quite distinct, the a-sulphonamide giving flocculent aggregates of flat plates, and the /3-sulphonamide a precipitate of well-defined minute needles.The p-sulphonamide is readily soluble in cold ether and benzene, and dissolves sparingly in water, in all cases being more freely soluble than the isomeric substance. It crystallises from water in thin, striated plates. When melted upon a microscope slide beneath a cover glass, it solidifies in white, detached areas, which, on examina- tion under a A'' immersion objective in polarised light, show a biaxial interference figure exactly resembling that seen on subjecting the a-sulphonamide to similar treatment. The double refraction is positive in sign, and weak. p-C hlorocamphenesulphonamide is readily soluble in alkalis, and dissolves to some extent in aqueous ammonia, being precipitated in both instances on the addition of acid. It sublimes when gently heated in a test-tube, and solidifies in the form of striated plates resembling those from alcohol or hot water.This amide was sub- jected to the same series of experiments as was the isomeric substance, and showed the same great stability; thus the action of reducing agents was carefully investigated, and in all cases it was found that they failed to displace any appreciable quantity of halogen. Hydr- iodic acid a t 100" was found t o attack the substance, iodine bcing liberated, but the quantity of amide reduced was probably n o t estimable. The amide was also boiled during several hours with ib strong solution of pure potash, and here again tlie liquid: on rtcidifica- tion and filtration, gave only a faint precipitate on the addition of silver nitrate.p- Chlorocampheneszdp7~ aniZide, CloHIPCI*SO2*NH.C6Hj. /3-Chlorocamphenesulphonic chloride and aniline interact vigor- ously, and unless care be taken the anilide is associated with oily impurities, which render purification very t,edious ; the anilide is best prepared in the manner described in the case of the a-compoiind, the reddish oily product being purified by fractional precipitation from alcohol, and subsequent treatment with animal charcoal ; the filtered solution of the less highly coloured portions then deposits the anilide in moss-like aggregates, and, after recrystallisation from cold dilute methylic alcohol, the substance is practically pure. /3-Chlorocamphenesulphanilide is excessively soluble in ether,DERIVATlTES @F CAMPBENE-SULPHONIC ACIDS.1563 benzene, chloroform, acetone, acd ethylic acetate, but is rather less so in petroleum and alcohol ; it is slightly soluble even in water, and is deposited from the solution as a colourless oil, which gradually solidifies. It crystallises from dilute alcohol, on spontaneous evapo- ration, i n fern-like masses of beautiful plates melting a t 103-105°; from almost every other solvent, however, it separates as an oil. The very small size of the crystals put tbeir optical examination out of the question; if, however, the substance be solidified between glass slips, it shows in convergcnt polarised light a biaxial interference figure, whose bisectrix is perpendicular to the slide ; the axial anglc is rather wide, the double refraction being weak and positive in sign.p . Chlorocamphenesuly hoizic acid, CIoH,,C1* S03H. As /3-chlorocamphenesulphonic chloride is hydrolysed only with great difficulty by water; the sulphonic acid is most quickly pre- pared by boiling the chloride with baryta-water, in which it dissolves with great readiness. I f the solution of barium hydroxide be strong, the barium salt crystallises out and may be filtered off and purified. The solution of the sulphonic acid, prepared from that of the barium salt by cautious addition of sulphuric acid, is concentrated on the water bath, diluted with alcohol, and evaporated once more, these processes being frequently repeated. It is imperative, however, that the solution should never become very concentrated so long as any hydrochloric acid remains, otherwise the sulphonic acid is partially transformed into the insoluble substance described later, and partially into a black gummy liquid from which nothing crystalline can after- wards be isolated.When, however, the hydrochloric acid bas been expelled and the solution finally evaporated nearly to drgness, the whole is diluted and allowed to remain in a desiccator during a few days, when it sets to a mass of crystals imbedded in a syrup. The mass may then be spread upon porous earthenware, or it may be quickly triturated with a small qnantity of ethylic acetate and filtered, in eit-her case the sulphonic acid remnias behind and may be then purified by drying it a t 100' and crystallising from benzene. /3-Chlorocampheaesulphonic acid is excessiyely soluble in water, b u t is not very deliquescent in damp ail..It cqstallises from water in leaflets which appear to contain water d crystallisation, for they fuse below the true melting point of the substance, and at 120° evolve bubbles of gas, presumably water-vapour ; it is also readily soluble in ethey, ethylic acetate, and acetone, less readily in chloro- form and benzene, and moderately soluble in iight petroleum. When anhydrous, it crystallises from benzene o r ether in four-sided leaflets, whilst from its solution in petroleum it ie deposited, on1564 LAPWORTH AND KIPPING : cooling, in well-defined needles which appear to be crystallographi- cally identical with the leaflets. The anhydrous crystmalls melt, without decomposing, tit 78-79', and may be heated to 130° without being much discoloured o r decomposed; at about 1 4 2 O , however, there is a sudden disengagement of gases, among which sulphurous anhydride may readily be detected. The crystals, both the needle-like form from peti-olenm and the plate-like form from ether, appear to pertain to the monoclinic system, They are elongated, flat leaflets, the two longer sides being cut very obliquely by two others; the extinction is parallel to the longer side and the large face of the crystal is probably parallel to the optic axial plane.The characteristic property of this sulphonic acid is the readiness with which it changes in presence of strong hydrochloric acid into an isomeric substance insoluble in water. It forms a number of well- defined salts, of which the following have been examined. Potassium /3-chlorocarnphelzesulphonate may be prepared by neutral- ising the solution of sulphonic acid with potassium carbonate, evaporating nearly to dryness, and then allowing it to crystallise.It is sliglitly soluble in alcohol ; the crystals from its aqueous solu- tion are liquefied by acetone, but are not dissolved by it. If forms small, thin, four-sided rectangular plates which belong to the ortho- rhombic system, and the optic axial plane is parallel to the large face, the double refraction is very weak, its sign, however, could not be determined owing to the orientation of the axial plane. Sodium P-chlorocamphenesu Zplion ate, prepared in a similar manner, crystallises in very thin plates. I t is very solu'ble in water and in methylated spirit, but is insoluble in acetone.Barium p-chlorocamphenesu1phonate.-The preparation of this salt has already been described. When quickly crystallised from hot solutions, it separates in long, transparent needles, whilst on elow evaporation it is deposited as well-defined, elongated, six-sided plates. It is readily soluble in water, but insoluble in alcohol and acetone. The crystals belong to the orthorbombic system, the extinc- tion being parallel to the longer sides of the plates, and the optic axial plane parallel to the large face. The obtuse bisectrix is parallel to the longer side of the plate, the optic axial angle being small, the double refraction weak and positive; the dispersion is very weak. The double refraction is rather weak. When a solution of ~-ch~orocamphenesulphonic acid in hydro- chloric acid is evaporated to dryness it leaves a dark-coloured pastyDERIVATIVES OF CAMPHENE-SULPHONIC ACIDS.1565 mass, which, on trituration with water, affords some considerable proportion of an insoluble substance ; a further quantity of the same product may be obtained by repeating the evaporation of the soluble portion after addition of hydrochloric acid. If thrown on to a filter and washed with water, the compound gradually loses all colour, and finally forms a, ~ h i t e , ca,mphor-like mass which is best recrjstal- lised from methylic alcohol. A qualitative examination served to show that the substance con- tained chlorine and sulphur; a portion, which was dried over sul- phuric acid in a vacuum and then burnt, gave the following result : C = 48.04 ; H = 6.42. 0.3446 gave 0.2547 CO, and 0.0835 H,O. C1,HlaCIS03 requires C = 47.90 ; I3 = 5.99 per cent. /3- C hlorocamphenesulpholactonc dissolves very readily in acetone, ethylic acetate, chloroform, benzene, and ethylic alcohol, but is some- what sparingly soluble in cold methylic alcohol, and is not soluble to any appreciable extent iu water. It crjstallises from xnethylic alcohol in radiate tufts of minute needles, or in elongated plates, and, on application of pressure, aggregates in much the manner as camphor does. It melts at 183*5--184*5O, without decomposing, and, after solidifying, melts again a t the same temperature. The compound is insoluble in boiling sodium carbonate solution, but dissolves slowly in hot solutions of barium and potassium hydroxides ; its solution in barium hydroxide, after elimination of excess of barium by means of carbonic anhydride, and evaporation to dryness, yields a sticky barium salt which dissolves readily in water and alcohol, but which has not been obtained in a crystalline form ; the sulphonic acid prepared from this salt showed a similar disincli- nation t o crystallise, and did not yield the parent lactone by the action of hydrochloric acid. The lactone did not suffer any ap- preciable loss of halogen in undergoing hydrolysis with baryta or potash. /3- Chlorocamphenesulpholactone dissolves readily in hot aniline, but without apparent alteration, being almost entirely recovered on dissolving the base in bydrochloric acid. It is likewise unaffected by alcoholic ammonia or by cohobation with fuming hydrobromic acid during some hours. When warmed with hydriodic acid, a portion appears to undergo some slight. change as is manifested by the liberation of iodine, but the original substance was recovered almost completely a t the end of the operation. It is not more readily oxidised with nitric acid than is the parent /3-chlorocamphenesulphonic acid ; it dissolves in the hot liquid but without production of brown fumes even after prolonged heating ; on evnpcrat ion i t is once more obtained unchanged ; chlorine is not1566 PERKIN AND HUMMEL : THE COLOURIWO MATTERS liberated in this instance, as the addition of silver nitrate fails to cause any precipitate of silver chloride. Chemica 1 Department, Central Y’echnica 1 College, City and Guilds of London Ihstitute.