TILDEN ON TERPIN AND TERPINOL. 247 XXVIII.--On Terpin and Terpinol. (Preliminary.) By WILLIAM A. TILDEN, D.Sc., Lmd. TERPINOL is the name given by L i s t to the liquid obtained by the action of dilute acids upon terpin hydrate, but the statements of Wig- gers (Ann. Che,m. Pharm., 1846, i, 251), L i s t (ibid,, 1848, 362), and 0 p p e n h e i m (ibid., 1864, 149), regarding the composition and pro- perties of this substance are at variance with one another. Tcrpinol is described by L i s t as a liquid of specific gravity *852, boiling constantly at 168". On the other hand, Oppenheim states that when terpinol is distilled it begins to boil at 165", and that the temperature gradually rises to 208". Moreover, 0 ppen heim asserts that distillation causes a decomposition in terpinol in such a manner that the first portions of' the distillate contain more carbon and less hydrogen and oxygen than the last.The analyses of Wiggers and L i s t indicate the formula C2,H3,0 or (C,oH1,)20H2. My experiments lead me to conclusions differing materially from those of the chemists to whom I have referred, and although the sub- ject is by no means complete, I beg leave to bring before the Society such results it5 I have obtained. Cqstallised Terpin, CloHPoOz.0H2. This beautiful compound was prepared by a process essentially the same as t,hat given many years ago by Wiggers. I find that it is advantageous to use a rather large proportion of nitric acid. A mix- ture of 1 measure of nitric acid (sp. gr. 1*4), 1 measure of methylated spirit, and 2 i measures of rectified turpentine oil becomes very warm,248 TILDEN ON TERPIN AND TERPINOL.and in about two days loses the smell of turpentine. If such a mixture is then poured out into an open dish, a small quantity of methylated alcohol being added every few days, it deposits crystals which in about a fortnight amount t o one-third of the weight of the turpentine employed. I have ascertained that no crystalline compound is formed under similar circumstances from the terpenes of the orange group ; also that the same compound is obtained whether American or French turpen- tine oil be employed. The crystals from both sources agree in melting point, in crystal- line form, and in giving an alcoholic solution which does not act upon a ray of polarised light. More crystals are obtained by prolonged exposure.Action of Dilute Hydrochloric Acid upon Teipirt. Separate experiments were made upon the terpins obtained from the two kinds of turpentine oil. The productf is, however, always the same, and it will be necessary therefore to quote only one experiment. TO 53t grems of crystallised terpin, boiled up with 700-800 C.C. of water, 12 drops of hydrochloric acid were added. I n a few minutes the crystals had disappeared, and the liquid, now turbid from the pre- sence of oily matter, was distilled. A distillate of peculiar and fragrant odour was obtained. When about half the liquid had passed over, a little water containing 12 more drops of hydrochloric acid was added to the residue in the flask, and the distillation continued until all the oil had distilled over.I retain the name terpinol for the oily pro- duct. When this terpinol was submitted to distillation, the temperature went up immediately to above 200", and all but a few drops came over between 205" and 215". When redistilled it came over again between the same limits of temperatnre, but no product of more definite boiling point was obtained. It undergoes no change of properties by distillation ; neither is it changed appreciably in composition. Two analyses were made, the one of the crude product dried by chloride of calcium, but not re- distilled (1) ; the other of the liquid redistilled, and collected between 205" and 215". 1. *18925 gram gave -5445 of CO, and -2080 of OH,. 2. -2803 gram gave *8110 of CO, and *3CIIO of OH,.These results give percentages of carbon and hydrogen, which closely approximate to the numbers calculated from the formula C,,H,,O or CIoH,,.H2O. 1. 2. Calculated. C . . . . 78.3 78.9 7 7.9 H.... 12.2 11.9 11.7TILDEN ON TERPIN AYD TERPINOL. 249 The formula CzoH,,O or (C1,Hl,),OH, requires C 82.75, H 11.72 per cent. Whether the formula CloHleO correctly represents the molecular weight of this compound is a question which cannot be finally deter- mined till the vapour-density has been taken and further experiments made. For the present I am much disposed to consider that this formula should be doubled, and that terpinol should be regarded as the anhydride or ether of terpin, beaying in fact a relatlion to that compound similar to the relation of common ether to ethylic alcohol.Terpin being- terpinol must be written Almost conclusive evidence of this is snpplied by the action of hydro- chloric acidj which does not give a monochlorcde, as might be expected if terpinol had the constitution expressed by CloH17( OH). Terpinol is a colourless, somewhat viscid liquid, inactive upon the polarised ray, and having a t 16" a specific gravity -9274. When dry hydrochloric acid gas is passed into it, the liquid becomes very hot, and assumes an intense purple colour. It ultimately sets into a mass of crystals, which after strong pressure become perfectly white. These crystals were analysed, and found to contain 33.94 per cent. of chlo- rine. The compound is therefore identical with the dihydrochloride, CIOHl8 obtained by saturating terpin with hydrochloric acid gas ; also by saturating with hydrochloric acid R solution of turpentine in ether or alcohol.This compound is entirely converted into terpinol by boiling for an hour 01' two with water. When this dichloride is boiled for a few minutes with a solution of sodium in absolute alcohol, a precipitate of common salt is thrown down ; and on adding water to the liquid an oil separates, which be- comes slightly yellow on exposure t o air. In contact with ordinary strong hydrochloric acid, it is instantly converted into a crystalline mass of dichloride. It was found to contain 24.9 per cent. of chlorine. The formula CloH18 { gFzH5 requires 16.24 per cent. of chlorine. I am therefore in doubt whether this compound was formed, or whether the liquid examined was a solution of the dichloride in the compound They melt a t 50".{ :;y Terpinol is miscible with alcohol in all proportions. If the alcoholic250 TILDEN ON TERPIN AND TERPINOL. solutiou is acidified with nitric acid and placed in a dish, it deposits in a few hours abundant crystals of terpin. This fact, and the peculiar odour of the liquid left in the preparation of terpin by the ordinary process, lead me to the belief that terpinol is formed at a certain stage of the reaction between turpentine oil, alcohol, and nitric acid. Cl0H1, + C?H,OH + HONO, = C10H160 + C,H,ONO,. Terpinol. The liquid which has begun to deposit crystals, when separated, washed free from nitric acid, and heated, evolves nitric oxide and then distils chiefly between 200" and 230".I look upon t-he production of terpin as probably accomplished through the intermediate formation of a compound of terpinol with the elements of ethyl nitrate, which is subsequently decomposed by water. Terpin. The same saccession of changes may be supposed to be repeated indefinitely. Action of Sdphuric Add on Terpin. 76 grams of terpin crystals were placed in a large flask, together with about 50 grams of sulphuric acid diluted with seven or eight times its bulk of water. Steam was passed through the mixture, till a.11 the oily matter had distilled over. After separating from the water the product was found to distil entirely between 177" and 187". After redistilIation a portion was collect,ed between 176" and 177", and analysed. It gave 84.7 per cent.of carbon and 11.8 per cent. of hydrogen. The formulze ( CI0H,,)@H2 and C~oHls require respectively 82.75 and 88.2 per cent. of carbon. The product was therefore presumed to be a mixture of terpinol with a hydrocarbon. It was boiled for two to three hours with about two volumes of water and one volume of oil of vitriol. The product fractioned and finally distilled from sodium gave about one-third of its bulk at 176-178", and this portion when burnt gave numbers corre- sponding with 87.33 per cent. of carbon and 11.8 of hydrogen in one experiment, and 87.43 per cent. of carbon and 11-79 of hydrogen in a second. Its vapour-density was taken by Hof mann's method in aniline vapour, and was found to be 68.8.TILDEX ON TERPIN AXD TERPINOL. 251 This, then, is evidently a hydrocarbon, having the formula C10H16.Theory. C ...... 88.2 H...... 11.8 Density.. 68 It seems to stand in the same relation to terpin as ethylene to common alcohol, and it is probably formed by a similar reaction. It is, how- ever, exceedingly difficult to get rid of the last traces of terpinol which accompany it. After very careful purification, another specimen boil- ing at the same temperature, namely, at 176-1$8", had a specific gravity of -8526 at 15". This compound is optically inactive. Treated with hydrochloric acid it gave no crystalline deposit, but after expo- sure in a dish for severa.1 days, the liquid left a fow crystals of the dichloride CloH,,C12. These were attributed to the presence of it small quantity of terpinol in the specimen operated upon.No crystalline nitroso-compound could be obtained by the action of nitrosyl chloride. When dilnt.ed yith chloroform, cooled, and mixed with two equiva- lents of bromine, it gave a dibromide which on heating splits up into hydrobromic acid and cymene, yielding a quantity of the latter com- ponnd equal to half the weight of the hydrocnrbon operated upon. In many respects this hydrocarbon agrees with the terpene charac- teristic of Russian turpentine oil, and described in a recent paper of mine (J. Chem. Soc., Februa,ry, 1878). It differs, however, from that compound in having no action on polarised light, and to the extent of about 4" or so in the observed boiling points. The oxidation products are of course very important, and I have ascertained that both terpinol and terpinylene, as this hydrocarbon may be called, yield, besides other acids, an appreciable quantity of toluic acid melting at 176". I do not regard this as a serious obstacle to the acceptance of the formula for the terpenes I have lately pro- posed. Assuming these hydrocarbons to consist of an open chain, which is liable to be closed by the removal of hydrogen from the ter- minal carbon atoms, it is not improbable that this closing of the chain may be effected during processes of oxidation. But that this occurs in a fortuitous and irregular manner is shown by the very small amount of the toluic or terephthalic acid ever obtained from any of the CI0HlG group. Cymene, CIoHl4, in which we must admit the closed benzene ring, yields under the same circumstances something like a third of its weight.