2410 MARSH: THE ACTION OF HALOGENS ONCCXLVL- The Action of Halogens on MercuricamphorCompounds.By JAMES ERNEST MARSH.THE work described in this paper is a continuation of that publishedby Mr. Struthers and the author on the mercury derivatives ofcamphor (Trans., 1909, 95, 1777).I n the former paper it was shown that di-iodoca.mphor wasobtained by the action of iodine on one of the mercury derivatives.It is now found that the same di-iodocamphor is formed from thethree mercury compounds, namely, those which have the formuk :of preparation is the same in each case The mercury compound istreated with an aqueous solution of iodine and potassium iodide,enough iodine being taken to combine with the mercury and thecamphor residue, and enough potassium iodide to hold the mercuriciodide in solution.The product of the reaction is extracted withchloroform, and the chlorof orm solution washed with sodiumhydroxide, dried, and rapidly evaporated. The di-iodocamphor isthen left in the crystalline form, and, after washing with lightpetroleum, is practically pure. A small amount of camphor-quinone, which is formed, is removed by the petroleum. If theoperation is carried out carefully, the yield is nearly quantitative,but if the substance is left too long in the chloroform solution theamount obt'ained is less satisfactory, as it decomposes in solution.Even when the substance is partly decomposed by being overheatedor left too long in solution, a good product can still be obtained byboiling with sodium hydroxide solution, and washing the residuewith petroleum.Di-iodocamphor, when in solution, rapidly decom-poses with separation of iodine. I n order to recrystallise it, the bestsolvent was found to be aqueous pyridine. It is very soluble inpure pyridine, and, on adding a little water, crystals at onceseparate. The crystals should be spread out in a thin layer to dry,as they rapidly decompose if heaped up in masses while still wetwith the solvent. The compound decomposes a little above itsmelting point, 108O, with evolution of iodine. It is stable inpresence of alkalis, and may be kept under a solution of sodiumhydroxide. It may be boiled with aqueous sodium hydroxide with-out decomposition, and it is not appreciably volatile in steam.C1()H140Hg212, (c10H140)3Hg412, and (c1(1H140)4H&12' The methoMERCURICAMPHOR COBIPOUNDJ. 241 1A ction of Oxygen on Di-iodocamphor.Camphor quinone.Although in the crystalline form, di-iodocamphor is stable whenexposed to air, when dissolved in chloroform it decomposes withseparation of iodine. One atom of oxygen takes the place of thetwo atoms of iodine, and camphorquinone is formed, along with asmall quantity of camphoric anhydride.To obtain camphorquinons in this way, air dried by sulphuricacid is bubbled through a solution of di-iodocamphor in chloroform.Iodine at once begins to separate, as is shown by the change in thecolour of the solution. Fresh chloroform is added, when necessary,to make good the loss by evaporation. When the action is finished,the product is mixed with a solution of sodium hydroxide anddistilled in a current of steam.The alkali serves not only to combinewith the free iodine, but also to convert the camphoric anhydrideinto sodium camphorate; otherwise the anhydride distils over inthe steam, and renders the quinone impure. The quinone appearsin the distillate as yellow crystals, and also colours the water yellow.It is extracted with ether or, better, with chloroform. The etherealextract gave, on evaporation, cryst*als melting at 196--197O, which,after recrystallisation from alcohol, melted at 198-199O. (Found,C=71*7; H=8*4.The yield of camphorquinone by this method is more than 90 percent. of that required by theory. This method should serve for theproduction of camphorquinone in any quantity from camphor, sincethe yield of the mercury compound from camphor and that ofdi-iodocamphor from the mercury compound are both nearlyquantitative.Further, all the mercury and iodine employed in thereactions can be recovered in the form of mercuric iodide, and usedagain for the preparation of the camphor-mercury compound.Camphorquinone is readily oxidised to camphoric acid by warm-ing with a solution of sodium peroxide; the crystals dissolve, andthe yellow colour of the solution disappears ; on acidifying,camphoric acid, melting at 186O, separates. It is converted bythe action of acetyl chloride into camphoric anhydride, meltingat 220O. This conversion of di-iodocamphor into camphorquinoneand camphoric acid shows that the iodine has replaced the hydrogenin the CH, group, which is adjacent to the CO group.It alsoshows further that, in the mercury derivatives, the Hg” and(HgI)’ groups are similarly situated in the ad-position. This wasanticipated by Mr. Struthers and myself from the circumstancethat the only ketones which we found to give mercury derivativeswere those having hydrogen in the a-position. The structuralCslc., C=72.3; E=8.4 per cent.2412 ACTION OF HALOGENS ON MERCURICAMPIIOR COMPOUNDS.relat,ionship of the mercury and iodine derivatives to camphor-quinone is shown by the lormulze:CHg T'sH14<&) ''Dimercuricamphor di-iodide. Di-iodocamphor. Cam phorquinone.Action of Bromine o n tlbe Mercu&anzphor Compounds.aaf-Di3 rornocamphor.The action of bromine on the mercuricamphor compounds is notso simple as is the action of iodine.I n the main, the reactionproceeds with the production of ad-dibromocamphor, melting a t6 1 O . The action is, however, complicated by liberation of iodineand its action, also by the oxidising action of the bromine, andfurther by the action of the hydrogen bromide produced in theoxidation.To prepare ad-dibromocaniphor, the mercury compound(C,,,Hl~0),Hg,12 is preferably employed, since it contains less iodinethan the other mercuricamphor compounds.The mercuricamphor compound is mixed with half its weight ofpowdered mercuric oxide, and this mixture is a.dded gradually toa solution in water of the requisite amounts of bromine andpotassium bromide, so that the whole of the mercuric bromideformed is dissolved in the water.The mixture is stirred all thetime with a turbine, and it becomes warm as the reaction proceeds.When cold, the mixture is extracted with chloroform. The chloro-form solution is washed with sodium hydroxide and water, dried,and evaporated. The crude dibromocamphor left on evaporation ispurified by solution in light petroleum. The petroleum solution isfiltered, i f necessary, from a small quantity of a crystalline sub-stance, which is referred t o later. On evaporation of the petroleum,the residue is distilled under diminished pressure. ucd-DibromWcamphor distils at about 175O/20 mm., and solidifies in the receiver.After recrystallisation from alcohol, it melted at 61O.(Found,Br =51*5.Mr. T. V. Barker examined the crystals with the goniometer,and found the measurements to be identical with those given byZepharowich for ad-dibromocamphor.By its production in this way, the dibromocamphor is broughtin t o relationship with di-iodo c amp hor , damp hor quinone, and cam-plioric a-cid ; hence its constitution as an aa'-compound is confirmed.The same dibromocamphor is produced by the action of brominein chloroform instead of aqueous solution. It is also obtained fromthe mercury compound C,,,HI,OHg,I,, and by the action of bromineon di-iodocamphor in chloroforin solution. It may be presumedCalc., Br =51-6 per cent.ACTION OF SODIUM AMAI,CIARI ON hIETHYLENE ETHERS. 2413to be also obtainable, like di-iodocamphor, from the intermediatemercury compound ( CloH140)3Hg412.The use of mercuric oxide in the preparation of dibromocamphorneeds some explanation.It was found to prevent the formation ofby-products. It probably acts by combining with any hydrogenbromide which may be formed, and thus preventing the decom-position of the mercuricamphor compound into camphor andmercuric bromide.The crystalline compound insoluble in petroleum is obtained whenmercuric oxide is not employed in the reaction; and at the sametime some a-monobromocamphor is formed. The former substancecrystallised well from alcohol, and melted a t 1 5 9 O . Numerousanalyses were made of this substance, prepared under varyingconditions. The analyses do not indicate the presence of a singlesubstance, but of a mixture intermediate between the compoundsCl,H,,0,Br2 and Cl0Hl4O,I2, with no simple relation between thebromine and the iodine atoms. When bromine acts on di-iodo-camphor, a similar substance is formed with relatively more iodineand less bromine in its composition, and of a higher melting point,namely. 1 7 2 O . A product of a similar nature is obtained withchlorine taking the place of bromine, when a chloroform solutionof di-iodocamphor is acted on by chlorine.When the mercuricamphor compound is treated with iodinebromide, IBr, or by iodine chloride, IC1, the principal product ineach case is di-iodocamphor.I wish to thank my assistant, Mr. F. Eall, for his excellent helpin this investigation.UKITERSITY LABORATORY,OXFORD