1296 HINKEL THE ACTION OF CHLORINE ON CXL.-The Action of Chlorine on 3 5-Dichloro-1 1 -d imethy l- A 4- cy clohexad ien e. By LEONARD ERIC HINKE'L. IN the study oif the conversion olf hydraaromatic derivative6 into compoands olf the aromatJa wries the action of bromine on 3 5-dichlorol-l l-dimeithyl-A2:4-~yclo~hexadiene was fully investi-gatled (Croasley T. 1904 85 264). It was shown that the reac-tlio8n was largelly influeaoed by oolnditlion of eurpelrimelnt~ 2 molecules of bromine giving rise tlcr a visoid liquid whioh on distillatioa gave 3 5 -dichlor(~-4-bro~moto~-xyleae and a qstialline solid C8H,Cl,Br,, preswn eld t a be di C;hl o'rotri bmm odime thy lcy clo hexeael, On tlhe othelr hand 1 molecule of bromine1 gavel as principal pro-d u d 3 5-dichlaro-6-bromo-o-xyle1ne1.Explanations of the produc-tion of the various suhtancw are suggested in the original paper, but as sevelral poinh remaineld to be cleared up the work wab repeateld using chlorine instead of bromine[ in the hope thatt more light would be thrown on the meohanism od this type of relaation. When 3 5-diohloro-1 l-dimehhyl-h2:4-~ycZohexadiene is treated witb ohlorinel the1 proiduclt consistts of a visoous syrup whioh yields a small quantitly oif a crystalline solid C,H,Cl,. The1 syrupy filtrate1 from the crystals yields 0111 distillation the two1 isomeric t richloro - ocx ylenes and also t&achloro+o-xylene. The1 oompon nd C8H,Cl is evidently a pendachlorrodimethytcycloihexem correspond-ing with and formed in a manner similar t o the diclhloroltribromo-dimethylcyclohexene demribed by Crossley (toc.cit .) and in like manner accounts for tlhe formation of 3 4 5-trichlorcr-o-xylene i 3 5-DICHLORO- 1 I-DIMETHYL-A2:4-CYCLOHEXADIENE. 1297 the filtrate from the orystals since the pentachlorecompound docompow on heatling into1 3 4 5-trichlorol-o-xylene. The farm-ation of pentlac;hlorodimethylcycZohexelne doee not however a m u n t for the production of elithelr 3 5 6-t75ichlo~ro~ol-zyJene or htr* chlorol-oi-xylene. The action of chlorine1 on dichlorodimethylcyclo-hexadiene must be more delep-seated since 100 grams of the latter yield only 28 grams of pentachlolroclimethylcycZohexene 18-20 grams of 3 5 6-trichlorol-o-xylene~ and 10-12 grams of a mixture of 3 4 5-triohloro+o~xylene and teltrachlom-ocxylelne.Moreover, when 1 molecule of chlorine acts on dichloroldimelthylcyclo-hexadienel the resulting liquid always contains a clonsidelrable quantity of the unchanged original compound together with 3 5-di- and 3 5 6-tri-chlorolxylenes; tlhe yield od 3 5 6-trichlo1rol-obxylene is small being oaly 16-18 grams frofm 100 grams of dichlolradimethylcycZohexatlielne. The product of the action of one malleoular proportion of chlorine on dichlorodimethylcyclo-helxadielne is probably tetrachlorodimethylcychhexelne~ (I) ; this substance is unstable$ and very reladily evohesl hydroigen chloride even at, low temperatures. probably forming a trichlorodimethyl-cycloihexadiene (11) whioh then slowly loses another molecule of hydrogen chloride yielding 3 5-dichloro-ol-xylene (111).A com-pound of folrmula I1 would combine witlh 1 modecule od chlorine in a mannelr similar to dichlorodimethylcyclohelxadiene yielding #' (111.) CMe<CCl=CCl>CH 'CMe - CC1 (VII.) 3 B** 1298 HINKEL THE ACTION OF CHLORINE ON a.n unstable substa*nm (IV) from which by 1- of 1 moileoule of hydrogen chloride 3 5 6-tsiohloro-o-xylelne (V) would result. The1 formation of teltsa7chlorol-o-xylelne oa,n be explaineld by sup-po'sing tlhah wit'h exmss of chlorina t'he tlwo compolunds I1 and IV are sucoessively f olrmeid and t8hajt more chlorine1 co,mb,ines with IV, yielding a.n unst,able substt.a,nco ha,ving tIha formula VI which immeldiatelly losea hydroigeln clhlolride giving rise1 t'o tet<ra,chlorol-oi xylelne (VII). The only point tlol be decidejd is the1 positlion off t,hel ohlorins ahoms in tIhe two1 pmsiblel t.riolilo~rol-o-xyleaes.3 4 5-Trichlorwo~xylene was t,helref ore synthelsis,ed from ol-$-xylidetnel whioh was chlolrina,ted, a.nd the a,niinol-group t'heln displaced by ohlorine. The 3 4 5-tri-chlora-obxylenel obt'aineld in t,his way melteld a8t 96O and its melt+ ing point rejmained unchanged when mixed with the substlance obmtained by heafing peint8a80hlorodim.ethylcyclolhexelnel. Co!nse+ quently the; olthsr tlrichloroio-xylene must have the chlorine atoms in t,hs 3 5 6-position. Bohh tlhel t,riohloro-exylelnes yield oln f urt'her chlorination the same1 t'eitlra,ohloro-oi-xyleae melting ' a't 223-224O which was identical with the compound obtained by t'he actioln of nitAcl a,cid on pent8a.chlorodimethylcycZohexenel and also with.the subst8ancel, melting a t 223-224O isohted in the1 distIilla,te olbhadned from t,he fil hate from pen t,a clhlotr odim ethyl cy clohexem . 3 4 5-Trichlo~ro-o-xylene1 oln brominatdon reladily yields 3 4 5-tr~cItZ~ol-6-broinzo~-o~xyLe.ne~ but on brominating 3 5 6-trichlorol-0-xylelllei in a simihr manner an unsxpecteid rea.ction takes place, giving rise t o 3 5-dichloro-4 6-dib,romo-oi-xyleae1 and not 3 5 6-taichlo~ro-4 -br omoi-o-xylene~. Bohh the1 tlricichlorctexylenes rewmble the diohlorobromo!-o-xylelnes in thelir behaviour towards nitric a,cid. Thus 3 4 5-tlri-ohlorow-xylelnel gives wit'h fuming nitriria acid 3 4 5-trichtlo~o-6-nitroLo-xyZe:me whe,rea.s 3 5 6-trichlolr~o-xyle~ne unde'r similas tre8a8tanelnt gives 3 5-dichloroi-4 6-dinitro-o-xylene.E X P E R I N E N TAL. Actiom of Excess of Chlovm'ne om 3 5-Dichloro-1 I-dimethyl-A2 4-cyclohexadiene. Selvem ty grams of freshly p r epareld di chlm oldimet h y 1 cy c lo+ hexadisnel were1 dissolvsd in 70 grams of dry chloroform and a rapid stream of chlorine was passeld in the1 whole1 being cooled in ice(. Hydrogen chloride1 was immeldiately elvolved and subae-queatly in tocrrents. After saturation with ohlolrinel the chloro-form was evaporated on the watelr-bath and the viscid yello liquid was plamd in a vacuum over sodium hydroxide whein i t gradually deposited oolourless crystals. These were collected (18.5 grams) (filtrate==) and after being rapidly washed with light petroleum purified by crystdlisation from alcohol (Found : C1= 62-62.C,H,Cl re,quires C1= 62.83 per cent.). 2 3 3 4 5-Pentachlwo~-l l-d2'rnethyl-h~-cyclohexene, is readily soluble in the) cold in ether chloroform acetone beinzene, o r methyl and ethyl alcohols and in light petroleum on warming. It crystallises in stout prismatic neeldles melting atl 103.5'. A c tion 01 f Hen t on Pen to c h lor.odim e t h y lcy cloh ex en e . The substance was heated atl 120-130° in a sulphuria acid bath, when it mellted to a colourlese liquid and copious evolution of hydrogen chloride occurreld. The liquid was thea removed from the acid-bath and heated more strongly until no1 further evolution of hydrogen chloride occurred and the liquid began t a boil. The rmidue solidified on coding and was crystallised from alcohol (Found Cl=61.16.3 4 5-Trichloro-o-xylelne is very readily soluble in ether chlors-f o m benzene light petjroleum or hot alcohol crystallising from the latter in masses of felt-like needles which o n pressing form a waxy mass melting atl 96O. It distils unchanged a t 261° is volatile in steam and is ewidelntly identical with the1 aompound describeid by Claus and Kautz (Ber. 1885 18 1369) who give m. p. 93O and b. p. 265O. On chlorination and brominatioa in the1 preseacs of iron it gives respeotivedy 3 4 5 6-te1t~rachloro~-o-xylene melting atl 223-224O (p. 1300) and 3 4 5-trichloro-6-bromo-o-xylene melting at 226O (p. 1300). Fuming nitric acid converts i t into 3 4 5-tri-chloro-6-nitro-o-xylene melting a t 149O (p.1301). Calc. C1=50-83 per cent.). Actiom of Nitric Acid om Pentachlorodimethylcycbhexeme. Five grams of the cyclohexenei derivative were heated with 40 O.C. of fuming nitric acid over a watelr-bath. A vigorous action elnsud and after heating for ten minutes the1 contelnts of the flask were pauretd into cold water. The pasty solid was dlected, washed witb water and after three crystallisations f r m elthyl aceitate the neeidles melltsd a t 223-224° ; the melting point was not altered on mixing with 3 4 5 6-te1trachlorol-ol-xylenq (p. 1300) (Found C1=58.4. Calc. C1=58.19 per cent.) 1300 HINKEL THE ACTION OF CHLORINE ON Examination of Filtrate A (p. 1299). The liquid was helated in a distilling flask tot 140° and gradually raised tlo 180'; a copious evolution of hydrogen ohloride occurred.The liquid was maintaineld a t 180-2QQo folr one hour and then gently distilleld three main fractions beling obtaineld boiling a t 225-245O 245-260° and 260-27Q0. The first two1 fractions, whiah partly sollidified oa keeping were subjeded to carelful and relpeiated fractional distillation and the main fractioa b. p. 230-240° solidified colmpletely o n c ing to a collourless orystal-line! mass which after being crystalliwd several time6 from alcmholl melteld sharply a t 47.5O and colnsisted of 3 5 6-trichloro-o-xylene (p. 1302) (Found C1= 50.99. C,H,Cl requires C1= 50.83 per mnt.). The residue of higher boiling point was addeld t o the1 third fradlion (b. p. 260-270°) and on submitting the mixture to repelated fradiolnal distillation two1 main fraotions b.p. 255-265O and 275-280° welrel olbtainetd. These were1 subjelcteld tot repelated fractiolnal orystallisatioa from aloohol and then from ethyl acetate, in which the fraction od higher boiling point is less readily soluble, and al partdal separation was effected yielding two1 substances one crystallising f r m alcohol in feilt,-likei neledles rnellting a t 96O and atl tlhe same telmperatme wheln mixed with 3 4 5-trichloro-o-xylene (p. 1299) the other crystallising from ethyl acetate in long, transparentl needles melting a t 223-224O and a t the same telmperature when mixed with 3 4 5 6-tetrachloro-o~xylene (below). Actionl of ChloTine om 3 4 5-Trvichlo~o~ocxyZe~~e Foil.maltiom! of 3 4 5 6-Tetrachloro~-o~-xylene (VII).Two grams of the substance were dissollved in 10 O.C. of dry uhlosoform and chlorine1 was rapidly passed into the solution in the prelsenaei oif a small quantity of iroln filings. On warming sub-stitution readily took placel. The chlorofolm was evaporated and the residue mystallised from ethyl aceitlatle. The substance1 is very readily solluble in elthelr alnd readily sol in chlorolform hot aloohol, or &hyl aueltate crystqallising from the1 lahtelr in long blender, glistening needles medting a t 223-224O (Claus and Kaxitz b c . c i t . give 215O). d c t b n of Bromin8e om 3 4 5-Tr'ichZovol-ol-xyleme Forlmaltiom o'f 3 4 5-Trichlo~o~6-brom~o~-o-zylene. The substance wa's dissolveld in at sma(l1 quantJty of ohlosoform, On wa4rming and broknine added in t>he prselnclel of iron filings substitution taok place and the sparingly soluble brmclderivative wpmated.The ohlorofom was evapwated and the residue dis-solved in benzene the solution being washed with water dried, mnoentrated and allowed ta crystallise (Found C1= 36.67 ; Br = 28.06. C,H,Cl,Br requires C1= 36.92 ; Br = 27.73 per oent.). The compound is readily soluble in ether or benzene sparingly so in chloroform or alcohol and crystallisee from ethyl acetab in slender glistening needles melting at 226O. A c t i m of Nitric Acid om 3 4 5-Trichlol.ol-cr-xylema F s r m t i m of 3 4 5-Trichloro-6-nitro-cr-xylene. Four grams of the substance were gradually added to 40 C.C. of fuming nitria acid and warmed un the water-bath for twenty minutes when the solid gradually dissolved.The mixture wag poured i n b water and the separated solid cryshllised from doohol in which i t is sparingly soluble (Found N=5*436. C,H,O~Cl requires N=5*5 per cent.). The compound is readily solubls in ether aaetone benzene, chloroform or light petroleum and moderately 80 in hot almhol or ho6 glacial amtic auid; i t orystallises from alcohol in stout, transparent crystals possessing a slight yellow tinge and melting at 149O. Synthesis of ,3 4 5-Trkhlsra-o-xylene. e4-Xylidine was acetylated and chlorinated as deercrihd by Crossley (loc. cit.). Three grams of the resulting 3 5-diahloro-a-Cxylidine were suspended in 15 C.C. of conwntrated hydrouhlorio aoid in which it is not soluble in the cold a solution of 1.5 grams of freshly prepared ouprous chloride in 15 0.0.of concentrated hydrochlorio aoid was added and a solution of 1.1 grams of sodium nitrite in the least amcrunt of wabr dropped into the mixture, which was heated on a water-bath to 60-70°. After one hour, the whole was distilled in a current of s h a m when solid pas& over which melted at 82O. After recrystdlising twice frm alcohol the crystals melted sharply at 96O and the mdting point wa4 not ohanged when the substance was mixed with the triahloro-o-xylene described on p. 1299. A c t b of One Molecular Propodion of Chlorine om 3 5-DichtOlro-1 1 -&met hyl-Az 4-cryclohexadiem. Dichlorodimet-hylcyclolhexadiene (1 mol.) was dissolved in twice ita weight of dry chloroform and the solution aoioled in a freezing mixture of ice and salt.Chlorine was paseed into tho niixture 1302 RINKEL THE ACTION OF CHLORINE ETC. and thel hydrogen chloride which was immediately evolved, absorbed in a soddime tube. The passage of ohlorine was stopped when the inoreasel in total weight of the apparatus was equivalent to one molecular proportion of ohlorins. On evaporating the chloroform a pale yelllow liquid remaineld which showed no signs of crysttallisation elven after remaining for a long time in a vacuum over sodium hydroxide. The liquid was heated to 150-180° for me hour when much hydrogen chloride was evolveid. The liquid was theln distilled and a clear yellow liquid boiling between 215O and 241° passed over. The liquid was submitted to careful and repeated fractional distillation and three fractions boiling at 217-220° 222-226° and 228-233O welrel collected.b . p. 217-220°.-This liquid when left in the air, rapidly darkened and resinifield and whein hydrolysed with 30 per cent. sulphuric acid yielded dimethyldihydroresorcin sholwing that it colntainsd 3 5-dichloro-l 1 -dimethylcyclohexadiene. Fraction b . p . 222-226°.-This liquid could not be separated into al portion boiling cmnstlantly a t 226O (3 5-dichlolra-o-xyletne). When treated with bromine1 in the premnm of iroln filings it gave 3 5-dichloro-4 6-dibromwo+xylene which after arystallisation from ethyl acetate melted a t 233O (compare Croesley Zoc. cit., p. 284) and an nitration gave 3 5-dichloro.4 6-dinitro-o-xylens melting a t 173-174" and identical with the compound obtained by the action of nitric acid on 3 5 6-trichloro-o-xylene (p.1303). B'ralctiom b. p . 228-233°.-The~ liqbid almost entirely solidified on cooling. The crystals werel callelated and the\ filt-rate was dis-solved in warm alcohol and the sollutdoln cooled in icei wheln a further yield of crystals was otbtained which after crystdlising several times from alcohol meilted a t 47.5O. This melting point was not altered when the substance was mixed with 3 5 6-trichlolro~ o-xylene (p. 1300). 3 5 6-T?.ic~.losol-o-lcylene is readily solublet in the cold in &her, benzene ohlorof ormy light petroleum or ethyl acetIate orystallises from methyl or ethyl alcohol in short ooloarless crystlals and oan ba distilled unahanged. It is readily acted on by chlorine in the presence od iron filings; the sotlid product crystallises from ethyl amt?tate in long glistening needles meilting a t 223-2240 and is identical with 3 4 5 6-tetrachloro-o-xylene (p.1300). Fraction A c t i m of Bromine om 3 1 5 6-Trichloro-cr-zyZene. Two grams of the subst8ancxtl were1 dissolveid in 10 C.C. of dry chloroform and exmm of br-inel was added in tlhet presence' of iron filings. On warming substitmuttion takes plaw readily. Th BARKER AND PORTER THE EFFECT OF ASYMMETRY. 1303 solid productt crystallised from eithyl acetate in long silky needles melting at 233O and this melting point was not changed when the substance was mixed with 3 5-dichloro-4 6-dibrolmo-o~xy1elne (Found C1,=21*65; Br==47*63. Cab. C1=21*32; Br=48-05 per cent.).Actiom of Nitric Acid o n 3 5 6-Trichloro-o-xyler~e. Five grams of the substance1 were( slowly addeld to1 30 0.0. of fuming nitric acid and warmeld on the water-bath when the sollid dissolved after which a rather vigorous action took place. The1 helating was continued for twelnty-five minuteis the mixture poured into oold water and the1 separated semi-solid after being washed with warm water cryst(a1lised from alcohol. Considelrable difficulty was experienced in purifying this material by me1ans of alcohol, and it was therefore twice1 recrystallised from light peltroleum (b. p. 40-60°) and finally from alcoholl. The flat plates obtained in this way melteld a t 174O and were identdfield as 3:5-dichloro-4 6-dinitro-o-xylene (Crossley loc. c i t . p. 284) (Found N= 10.51. Calc. N=10-56 per cent.). The author wishes t'o express his indebtedness to1 Colonel A. W. Crossloy C.M.G. folr suggesting the above investigation and for much valuable help and advice throughout; t'hanks are1 also due to the Raelarch Fund Committee of the Chelmical Society for a grantl which has in part defrayed the! expensea of this investigation, CHEMICAL DEPARTMENT, KINCI'S COLLEGE LONDON. [Rcceived September 241h 1920.