MAXINILIAN SCHMIDL ON OIL OJ!’ CAJEPUT Q)pl the Consfiifaatbn of 8il of Cajepuf. By EZaximilian Schmidl. (From the Transactions of the Royal Society of Edinburgh Vol. XXII., Part TI. p. 360.) OIL OF CAJEPUT is prepared in the East Indies by distilling the leaves of Melaleuca Lewcodendron with water. * It was formerly used to a great extent as an external and even as an internal medi- cine; but has now become more or less obsolete and is seldom NAXINIILIAN SCHMlDL ON THE met with in a pure or unchanged state except in the hands of wholesale druggists. As introduced into Europe it possesses a light green colour resembling that of a dilute solution of chloride of chromium which is caused by a resinous colouring matter dis- solved in it in very small quantity.The colour of the crude oil is also partly due to copper the presence of which may be accounted for either by the use of a copper head in the distilling apparatus of the Indians or by inten- tional adulteration resorted to for preserving the green colour of the oil which otherwise changes gradually by oxidation to a red-dish-brown the oil then becoming unsaleable for medicinal pur- poses. That the oil possesses a green colour of its own is proved by the fact that the cdour remains after the complete removal of the copper by sulphuretted hydrogen. Oil of cajeput consists mainly of the bihydrate of a hydrocarbon (cajputene) isomeric with oil of turpentine. Its specific gravity is 0.926 at 10"C. On submitting it to fractional distillation bihydrate of cajputene which constitutes about two-thirds of the crude oil passes over between 175' and 178"C.; smaller fractions perhaps products of decomposition are obtained from 178"to 240" C.and from 240"to 250" and at 250" only a small residue is left con-sisting of carbonaceous and resinous matter mixed with metallic copper. On treating this residue with ether a green solution is obtained which when evaporated leaves a green resiu soluble in the portion which boils between 175" arid 178" C. and capable of restoring its original colour. CAJPUTENE;, C,,HzG,is obtained together with two isomeric hydro- carbons (isocajputene and paracajputene) by cohobating bihydrate of cajputene with anhydrous phosphoric acid for half an hour and then distilling off the liquid whereupon cajputene passes over at 160"-16~"C.isocajputene at 176"-178"; and paracajputene at 310"-3 16". -Cajputene is perfectly colourless and has a very pleasant odour resembling that of hyacinths. Sp. gr.=0*850 at 15" C. Vapour-density by experiment 4.717 ;by calculation supposing the mole-cule to occupy 4 volumes of vapour it is 4,712. Cajputene is permanent in the air. It is not affected by iodine at ordinary temperatures but at a higher temperature hydrogen is evolved and a black liquid is formed. Bromiize acts quickly on it producing a dark viscid oil. With gaseous hydrochloric acid it forms a beautiful violet liquid but no crystalline compound even at-'10" C. A mixture of' ordinary nitric and sukhuric acids act upon it with violence forming a yellow brittle resin.Cajputene is insoluble in atcohol but dissolves in ether and in oil of turpentine. Isocajputene C,oH,6.-Obtained (1.) as above. (2.) By dis.. CONSTITUTION OF THE OIL OF CBJEPUT tilling the bihydrate of cajputene with oil of vitriol. It is an oil boiling between 176' and 178" C. Its odour is less agreeable than that of cajputene and becomes more pungent and aromatic by exposure to the air the oil at the same time acquiring a yellow colour. Sp. gr. =0.857 at 16"C. Vapour-density of (1)=4%2 ; ot (2) =4.52. Iodine bromine gaseous h~dro~hloric acid and a mixture of nitric and sulphuric acids act upon isocajputene in the same manner as on cajputene. With oil of vitriol and with diZute sul- phuric hydrochloric or nitric acids (neither of which acts upon cajputene) it forms dark viscid liquids.Isocajputene is insoluble in water and in aZcoho2 but mixes in all proportions with ether and with oil of turpentine. Paracaj putene C,,TI,,.-Obtained as above mentioned by dis-tilling bihydrate of cajputene with anhydrous phosphoric acid ;and passes over between 310"and 316"C. It is very viscous has alemon-yellow colour and in certain directions exhibits deep-blue fluores- cence. Vapour-density by experiment 7.96;by calculation (4vd.) =9-424. The difference between the experimental and calculated vapour- densities i3 probably due to decomposition taking place at the high temperature required for the determination. Paracaj putene oxidises rapidly in contact with the air acquiriq a red colour and resinous consistence.A mixture of nitric and suhhuric acids does not act so violently on it as on cajputene and isocajpritene. With hydrochloric acid gas it forms a dark viscid liquid which does not yield crystals even at-10" C. It is inso-luble in water alcohol and oil of tarpentine; soluble in ether. HYDRATES CAJPUTENE.-~.Mono-hydrate C2,HI6.HO.-OF Obtained by the action of oil of vitriol on oil of cajeput. When the crude oil is raised to the boiling point in a deep open vessel and oil of vitriol continuously dropped into it violent ebullition takes place accompanied after a while by a peculiar crackling sound. As soon as this is observed the flame must be lowered and the acid very cautiously added till the liquid suddenly assumes a dark colour extending in an instant from the surface throughout the whole depth.The vessel must then be immediately removed from the fire otherwise further decomposition will take place attended with evolution of s ulphurous acid. The upper oily liquid is separated from the acid on which it floats then well washed and distilled and the portion which passes over from the 170"to 175" is collected and rectified. It is an oily liquid having a vapour-density of 5.19 to 5.27; by calculation (4 vol.) =5-024. This vapour-density is anomalous inasmuch as the molecule C,,H1,O which occupies four volumes of vapour contains but 1 atom of oxygen. Probably the true formula of the body is MAXIMILIAN SCHNIDL ON THE C4-,H3402= C40H32+ H,O, this molecule splitting up at high temperatures into C401232 and H,O, each of which occupies four volumes of vapour and consequently the two together occupy 8 volumes.* b.Bihydra te C,,Hl,0,=CY,,H16~2H0.-Th~s is the chief con- stituent of oil of cqjeput and passes over in the fractional distilla- tion between 175" and 178" C. After rectification it is a colourless oil which boils constantly at 175" has a specific gravity of 0903 at 17" and vapour-density = 5.43j the calculated vapour- density (4 vol.) is 5-35. When exposed to the air for a considerable time in the moist state it changes to a reddish liquid which ultimately exhibits a rather strong acid reaction with litmus. Iodine dissolves in the oil and under certain circumstances forms crystalline compounds (p.69). Bromine acts quickly upon it and forms crystalline compounds under similar circumstances. Chloriae gas passed into the oil raises the temperature but does not appear to act upon+ it further ; but nascent chlorine (evolved by passing hydrochloric acid gas into the oil mixed with dilute nitric acid) converts it into bicliloride of cajputene CzoH16C12. Anhydrous phosphoric acid heated with the bihydrate takes away the whole of its water converting it into cajputene isocajputene and para- cajputene (p. 64). Chtoride of zinc likewise dehydrates it but less completely. Strong su&huric acid acts but very slowly on the oil at low temperatures; but if the temperature be allowed to rise sul-phurous acid is given off and the oil blackens and ultimately suffers complete decomposition.If the action be checked at a certain point a sulpho-acid is formed which yields a soluble baryta-salt. Strorig sulphuric acid dropped illto the oil at the boiling heat in the manner described at page 65 takes away half the water forming mono-hydrate of caj putene. DiZuute suZplhuric acid on the contrary causes the bihydrate to take up 4 At. more water converting it into C,,H16+ 6EO. Fuming su@huric acid converts the bihydrate into a thick brown liquid which boils above 360". Fuming nitric acid rapidly oxidises the oil even at ordinary temperatures forming large quantity of oxalic acid. Ordiiiary nitric acid produces the same effect at the boiling heat but at ordinary temperatures it over acts very slowly converting the oil into a red liquid.Distilled permanganate or bichmmate of potassium in presence of sulphuric acid it forms a thick resinous liquid. It does not appear to be altered by digestion with peroxide of lead. In contact with aqueous potash or when dropped into melting potash it forms a soluble salt the acid of which is precipitated as a resin by hydrochloric * See "Observations on Anomalous Vapoiir-densities," by Dr. Hofmann; (Pro. ceedings of the Royal Society vol. x pp. 224 596); also Gnzelin's Handbook, English Edition xiii 487. CONSTITUTION OF THE OIL OF CAJEPUT. 6'7 or sulphuric acid. Heated with sodium it forms a crystalline mass soluble in water and alcohoI and consisting of soda and an organic substance which is separated by strong acids in the form of a fragrant resin.When the vapour of the bihydrate is passed over red hot soda-lime a yellow oil distils over having a peculiar odour quite different from that of the bihydrate and at the same time the soda-lime becomes blackened by deposited charcoal and when treated with acids gives oft' a large quantity of carbonic acid. The yellow oil thus formed yielded by distillation a fraction boiling between 180"and 185"C. which gave in two analyses 79-76 and 80.03 p. c. C 12920 and 12.07 H agreeing nearly with the formula C26H24026 which requires 79-59 p. c. C 1244 H and 7-97 0. Bihydrate of cajputene dissolves in all proportions in alcohol ether and oil of turpentine.c. Hex hydrate C?oH2?06 =~20~16,6~0.-~~~oduced by the action of dilute sulphuric acid on the bihydrate or on crudeoilof caje- put. Two parts of dilute sulphuric acid are added to 1part of the crude oil; and the mixture is well shaken €or several days till the watery layer acquires a yellowish colour and then left to itself for about ten days whereupon it deposits crystalline tufts of the hex- hydrate adliering to the sides of the vessel. The crystals melt at 120"C. and solidify again at 85'. On sub-mitting them to dry distillation an oily liquid passes over and condenses again in the colder parts of the apparatus apparently as the unaltered hexydrate. The crystals dissolve sparingly in cold easily in boiling alcohol. Crystals having the same composition were deposited from a secon-dary fraction of crude cajeput-oil which distilled at 216"-2230" C.and was left for a very long time moist and exposed to the air. The crude oil mised with nitric acid andalcohol changes in the course of seven or eight months into a black heavy liquid in which crps- tals are suspended perhaps consisting of the hexhydrate. The same compound appears likewise to be formed in beautiful long prisms when the crystalline inass produced by passing hydrochloric acid gas into rectified oil of cajeput is thrown into water or alcohol. OF CAJPUTENE. CHLORIDE C,,H,GC1,.-Produced by the action of nascent chlorine on the bihydrate. When the portion of cajeput oil distilling between 175" and 178"C. is mixed with very dilute uitric acid and hydrochloric acid gas is passed into the liquid a violent action takes place in a few minutes yellow and red fumes of chlorine and nitrous gas being evolved and if the passage of the gas be continued chloride of cajputene ultimately sinks to the bottom as a limpid brown oil which may be freed from adhering nitric and nitrous acid by distillation over strong potash-ley.It has a fragrant odour and may be kept for any length of time MBXIMILIAN SCHblIDL ON THE without alteration but is decomposed by distillation. Boiled with nitrate of silver it detonates in a peculiar manner and forms chloride of silver. Crystals %-ere once obtained by keeping the oil at a low tempera- ture but not in suffcient quantity for analysis.MONOHYDROCHLORATE C,oH,6,HC1.-Obtained OF CAJPUTENE. by distilling the bihydrochlorate and collecting apart the fraction which boils at 160". A product having the same composition is obtained by treating the bihydrochlorate for several days with aqueous or alcoholic potash ; but its odour is different from that of the product obtained by simple distillation of the hydrochlorate and resembles that of pelargonic ether. OF CAJPUTENE. BIHYDBOCHLOBATE C2,H,,,2HC1.-Obtained by passing hydrochloric acid gas through rectified cajeput-oil mixed with a third of its volume of alcohol or strong aqueous hydro- chloric acid. Crystallihes from alcohol in beautiful radiating tufts. Melts at 55" C. and solidifies again at 30". It has no taste or smell.By dry distillation it gives off hydrochloric gas at 60" and splits into several fractions one of which is the monohydrochlorate. It is also deprived of half its chlorine by heating with aqueous or alcoholic potash. It dissolves sparingly in cold easily in boiling alcohol or ether. When hydrochloric acid gas is passed through rectified oil of cajeput kept at a low temperature a violet liquid is formed which in 10 or 15 minutes solidifies in a crystalline mass. This crystal- line compound is extremely deliquescent liquefying rapidly even when pressed between blotting paper cooled to -25" C. ;the result- ing liquid rapidly gives off fumes of hydrochloric acid and is com- pletely decomposed by distillation. If the crystalline mass imme- diately after its formation be thrown into water or alcohol beautiful long prisms are formed after a few days apparently consisting of hexhydrate of cajputene.BROMIDE CAJPUTENE. OF C20H16Br4.-Obtained by the action of bromine on oil of cajeput. When dry bromine is dropped into the rectified oil a very brisk action takes place and the sides of the vessel become covered with yellow needles which however soon disappear; but if the addition of the bromide be continued till the reaction almost ceases a dark thick viscous oil is formed which after several weeks deposits a granular substance. By boiling the mixture with alcohol the granular substance is extracted ; a heavy oil is left behind; and the alcoholic solution on cooling deposits bromide of cajputene as a soft crystalline substance having a fatty lustre and much resembling cholesterin.Bromide of cajputene melts at'60" C and solidifies again at 32". CONSTITUTION OF TI-IE OIL OF CAJEPUT. By dry distillation it yields a liquid which crystallises again in the cooler parts of the retort. It is not altered by boiling with aqueous potash. It dissolves in ether and in boiling alcohol. Rectified oil of cajeput shaken up with bromine-water forms a red resin from which a solid substance separates in small white prisms extremely deliquescent and rapidly decomposing. Another crystallised bromine-compound (probably a hydro-bromate analogous to the hydriodate) is formed in the same manner as that compound. HYDRIODATECAJPUTENE.-a.Anhydrous C20~16,HI.-Ob-OF tained by adding a solution of phosphorus in bisulphide of carbon to a solution of iodine and oil of cajeput in the same liquid.Brisk action then takes place the vessel becoming very hot; red oxide of phosphorus is precipitated ; the oily liquid becomes reddish ; and gives off vapours probably containing phosphurretted hydrogen and if left to itself for 10 or 12 days deposits crystals of the hydriodate. The reaction probably takes place as represented by the equation 3C2oHl~+ 3PI + 6H0 = 3C20H,71+ PH + PO + PO The crystals of the hydriodate are deposited in cells like those of beehives and possess a black metallic lustre. They are soluble in alcohol and in ether and are very stable not being altered even by boiling with potash.b. Hydrated C2,H1,10 = C20H16HI+ HO. or Hydriodate of Monohydrate of Cajputene. C,oH,70,HI.-When iodine is added in small quantities to cajeput oil crude or rectified at ordinary tem- peratures no visible action takes place (if external heat be applied the action goes too far and nothing but a viscous mass is produced which does not crystallise) ;but on stirring rather constantly the Rction is assisted partly by the heat resulting from the friction of the glass rod partly by the mechanical distribution of the iodine md the temperature of the liquid soon rises from 10"to 40"C. The addition of iodine must then be discontinued asd the vessel immersed in cold water. A black crystalline compound then separates after a short time ;and on separating this substance from the oily liquid by filtration pressing it between blotting paper and when it is nearly dry dissolving it in alcohol or ether a solution is obtained from which the hydrated hydriodate crystallises in prisms having a fine yellow-green colour and metallic lustre.They are very deliquescent and melt at 80"C. into a liquid which does not recrystallise in the cold. Potash-ley liquefies the compound abstracting part of the iodine and with the aid of heat abstracts the whole. It is insoluble in water and is not decomposed thereby; very soluble in alcohol and ether.