A. OPPENHEIM ON THE V.-On the Camphor of Peppermint. By A. OPPENEEIM, Ph.D. THEcamphor of peppermint known as constituting the stearop- tene of the essential oil <Jf Mentha piperita has lately been obtained in larger quantities so as to allow of tl closer examination being instituted than has hitherto been possible. It arrives from Japan in coarse earthenware jars merely protected by paper covcrs and consists of a mass of small white fragrant prismatic crystals resembling sulphate of magnesia which salt in fact seem to be constantly used for the purpose of adulterating the Japanese peppermiut-camphor rn from ten to twenty per cent. of that salt may be scparatcd from the camphor by washing it with water. When washed with warm water the peppermint-camphor melts and CAMPHOB OF PEPPERMLNT.on congealing forms itself into a hard crystalline mass. It melts at 36 (1 and distils without decomposition at 210’. These pro- perties very nearly coincide with those established by Dumas,* for the stcreoptene of Americah oil of pcpperrnint. The compo- sition of thcse two substances is exactly the same viz. 0.260 grru. of Japanese camphor of peppermint dried at looo gave 0.732grm. of carbonic acid and 0.315 grm. of water or in 100 parts. Japan camphor Dumae of peppcrmint. American camphor. Calculated. C i6.93 76-5 76.92 H 13-40 13.1 12.82 0 , 9 10.26 This corrcsponds with the formula established by Dumas C,,€I,,O.t Walter verified this formula in 1830 by determining the vapour-density of the corresponding hydrocarbon Cl,HIB.The nature of this body which on many grounds claims our attcntion has not been determined by either of these chemists. Whether it be an alcohol an aldehyde a ketone or of a nature less distinct (like the hydrates of oil of turpentine) it possesses particular interest from the fact of its bordering on’the two great groups of organic chemistry the group of fatty and that of aromatic bodies. To the former it is related by being isomeric with capric aldehyde and to the latter by diff’ering from a number of aromatic bodies merely in tlie number of its hydrogen-equi- valcnts. The camphol of Berthelot C,,H,,O differs from it by two equivalents of hydrogen ; common camphor Cl,H,60 by four ; the cuminic alcohol of Rossi C,,H,,O also thymol and carvacrol by six; and cutninol C1,Hl20 by eight equivalents of hydro-gen.The relation of camphol and camphor being that of an alcobol and its aldehyde,$ the position which the camphor of peppermint holds towards them mill call for our particular attention from their being related not only as regards their composition but also with respect to their physical properties. The peppermintcam- phor turns the plane of polarization to the left. Gerhardt Trait6 de Chimie Organique vol. ir. p. 357. + C = 12; H = 1; 0 = 16. Berthelot “La Chimie Organique fondue sur la Synthbee.” A. OPPENHEIM ON TH.E A preliminary determination of its rotatory power has been arrived at by the aid of Dubosc's saccharometer.A tube 23mm. in length waa filled with a'10 per cent. solution of peppermint-cam-phor in alcohol when it was found to deflect the plane of polariza-tion as much aa a plate of quartz QUmm. thick. This corrc-sponds to an angle of 10*56'=a and to a molecular rotatory power,-a [a] = -= 59.6. 1€6 Peppermint-camphor is but slightly soluble in water although it imparts to the liquid 8 strong odour and taste. It is very soluble in alcohol ether sulphide of carbon and in fatty and essential oils ; insoluble in aqueous solutions of alkalies. From an alcoholic solution of soda it crystallizes in long needles. A current of sul- phurous acid or of hydrochloric aoid gas dissolves it. By evapo-ration the acids pass off leaving the peppermint-camphor unaltered.Concentrated acids especially nitric sulphuric hydrochloric formic acetic and butyric acid dissolve it very freely. From these solutions it is separated by water as well as' by alkalies as an oil which soon solidifies and then exhibits the original properties of the camphor. When concentrated acetic acid is heated with peppermint- camphor in a scaled tube for ten or twelve hours at about 120°C. these two bodies combine into a light oil no longer decom- posible by water or by cold solutions of alkalies. After washing with carbonate of soda and drying over chloride of calcium it boils between 222' and 224" C. without decomposition. I. 0.303 grm. of this distillate yielded hy analysis 0314 grm. of water and 0.827 grm. of carbonic acid. The same body is obtained by the action of anhydrous acetic acid on peppermint-camphor.11. 0.330 grm. thus prepared gave 0.303grm. of water and grm. of carbonic acid. T. n. Calcnlnted. C 73-06 72-58 72-73 H 1~04 11.18 11-11 This agrees with the formula,- Tlirit is pcppcrmiiit-cnrnl)lio~ i ii which onc cquivalcnt of liyilrogcn his hccn siibstitutctl by acctyl so ;~sto form ;Icompoitnd cthcr. Tliis Iiotly is Iiiglily rcfractivc mid tlcflccts the planc of polari- zntioii to thc lcft nioi-c stroiigly tli;iii tlic camphor from which it is dcri\*cd. By 1)rcliniiii:iry ol)scr\liLtiori with tlic sacclinrom(:tcr its molcculrrr rotal.ox-y power [a]1111sIiccii fouiid = 1I,laO. 1Iydratc of harytn. docs not sc'citi to tlccomposc it ; hut 1)y licntiiig it with mi alcoliolic solution of sotla to 1%" C.for tlircc Iioiirs it is pcrfcctly dccompoeccl iiito acctntc of so[l;i mid an oil wliicli soon coiigcals iiito n crystnlliiic mass not iiiilikc conimoii camphor. Aftcr \icing iircsscd 1)ctwccn blottiiig-l)apcr it distils at 210' C. fuscs at 3.10 mid cxliiliits othcrwisc tlic original propcrtics of pc~q)cnnint-cnniplior. I1ntyric acid comhics with pcppcrmint-camphor on bcing hcatcd with it to 200°C.for about thirty hours. The product mas scpnratcd into two parts distilling from 230' to 240" and from 210 to 250' respectiwly. Tlic fornicr of tlicsc portions gavc thc following analytical rcsults :-0.287grm. of thc liquid gnvc 0.303 grm. watcr and O'i92 grru. of carbonic acid corrcsponding to tlic forniuln which is that of butyratc of InciitIiFl; in 100 parts,-Foiind.Calculatcd. c 74.84 $4.33 H 1174 11.50 A prcliminary dctcrniinntioii of its rotatory ponw gnyc [a] = 88-8(:'. A coriccntrntcd solutioii of liydrochloric acid acts on pcppcr- mint-camphor at 100° C. But it is neccssary to licnt thcm together for a wcck iii ortlcr to olitaiii n coiisitlcrablc qiiantity of chloridc of mcntlipl. lit a tc.mpmtiirc of 1%' C. twcnty-four Iioiirs siifficcl to coiiiplctc tliis rcartioii. Tlic elilorirlc of mc-iitllj*lmay I)c \vaslicd witli carlionatc of soda hiit it rlocs not 1)c:ir tlistillatioii. Tlic followjng analyscs mcie m;itlc with non-distillcil portions of tlic liquid dricd ovcr chloridc of cn1ciii.m :- A. OPPENHEISI ON TEE I.0.323grm. gave 0.332 grm. of water and 0-794 grm. of car- bonic acid. 11. 0.382 grm. gave 0.296 of chloride of silver. 111. 0.310 grm. gave 0.206 grm. of chloride of silver. This corresponds to the formula C1,HlSC1 or in 100 parts 1. n. 1x1. Calculated. C 67.06 > * 68.62 H 11-32 , >> 10-89 c1 , 19.16 19-67 20.34 The same body was obtained by Walter by the action of perchloride of phosphorus on peppermint-camphor. Iodide and bromide of phosphorus react very strongly on this body; but as the resulting bodies bear distillation aa-little as the chloride of menthyl these methods are not advisable for obtaining them. Hydriodic acid combines with peppermint-camphor at about 120° C. Sodium acts very strongly on peppermint-camphm It dis-solves therein when fused; and disengages hydrogen.By raising the temperature about one equivalent of sodium map be made to unite with the fused camphor forming a vitreous transparent mass white originally but becoming brown and moist when exposed to the air. It is decomposed by water but soluble in absolute alcohol and in iodide of ethyl. The reaction of this body on the sodium-compound is not so simple as might be expected. When heated to loo" the transparent liquid solidifies but continues to be soluble in a mixture of ether and alcohol. From this solution deliquescent crystals may be obtained which contain iodine sodium carbon and hydrogen ; but continued evaporation decomposes these crystals into iodide of sodium and an oily sub-stance which does not appear to be the mixed ether expected to be formed by such reaction.The products of this and of similar reactions form the subject of the continuation of these researches. From the compound ethers and the sodium-compound hitherto obtained it is already evident that the caniphor of peppermint is a monatomic alcohol having the formula- C10H191 H O* It belongs to the general type and is therefore homo- logous with the allylic alcohol of IIofman and CiLhours and with tlic acctylic alcoliol of 13t:rtliclot. 11s it is isologous with cam-pllolic alcohol the iiatnc w~u!/idicufco/id or menthol may perhap bc advantageously substituted for that of camphor of pcppcrmint. Tfic corrcspontling hydrocarbon menthene C,,H, which Waltcr obtained by the action of phosphoric acid may likcwise bc protluccd in various other ways.It has been found among the products of tlic reaction of chloride of menthyl on ethylate of sodium. The most advntitagcous may of preparing it scems to he to react on mcritliol with chloride of zinc. Prepared in this way the meutlmic has no action 011 polarized light. It boils at 163' C. 0.227 gm. yielded by analysis 0-282grm. of water and 0.733grm. carboiiic acid ; in 100 parts-Found. Caldated c SG.39 86-94 I1 13-65 13-05 Bromine docs not combine directly with this hydrocarbon. It reacts on it wry violently disengaging currents of Pydrobromic acid and forming various products of substitution of no stability whatever even at ordinary tcmpcratures.By adding drop by drop two eqiiivalents of bromine to one of mcntheue monobroniiiiatcd menthene ClOI~,,Brmust be formed which by the action of oxide of silver or of hydrate of sod:i might he traiisformcrl into camphol. But this reaction gives risc to a hydrocarbon CioH16 boiling between 170" and 175' C. C,,H17Br + =' -I-14I 0 + C,,H,G. The acid corresponding to mcnthol is identical or isomeric with the campliolic acid of Delalande Cl,Hl,O,. The ordinary oxidizing agcnts such as nitric acid chromic acid &c. do not protliicc this acid. They at once attack the carbon of thc meritholic alcohol. I hopc howevcr to be able to produce it by a less direct method of osidation.