Acid oxidizing agents convert it into terephthalic and terebic acids, whilst alkaline potassium permanganate in dilute solution oxidizes it to pinene glycol, C10H1e(OH)2, pinonic acid, CMHMO3, pinic acid, C.H14O4, &c., the products of the reaction varying according to the tem erature (G. V/agner, Bef., 1894, 27, p. 2270; F. Tiemann and F. Semmler, Bef., 1895, 28, pp. 1344, 1778). Concentrated sulphuric acid converts it into camphene; and an alcoholic solution of sulphuric acid gives terpinene and terpinolene. When heated to 250-270° C. it yields dipentene; the moist halogen acids at ordinary temperature convert it into the dihalogen halides of dipentene. D hydrochloric acid gives pinene hydrochloride (artificial camtihlor), C1<>H11Cl, <a white crystalline solid identical with bornyl chloride which melts at 131 ° C. Elimination of halogen hydride by means of a weak alkali (e.g. soap, silver acetate, &c.) converts it into camphene. Thus the conversion of pinene into its hydrochloride is probably accompanied by an intermolecular rearrangement-H1C~ C» Clrli-' (HaC)Cl - C - CH— H2C1C(CH3)~CHCI fI(CH1); CH2-> H2(lI (l(CH:)z CH; -> ' C(CHz)2 HaC -CH -I H1(l~(iH J HQC - CH—CHz

Pinene. Bornyl chloride. 4

Nitric acid in aqueous alcoholic solution converts hydrate. Pinene nitrosochloride, C101-116NOCl, was in 1874 by W. A. Tilden (Jahresb., 1874] p. 214) chloride and a mixture of pinene and c loroform. (Ann, 1889, 253, p. QPI) prepared it by the action it into terpin

first obtained

from nitrosyl

O. Wallach

of acetic acid

and ethyl nitrite on oi of turpentine in presence of fuming hydrochloric acid. W. A. Tilden (Jour. Chem. Soc., 1904, 85, p. 759) showed that strongly active pinene gives bad yields of the nitrosochloride, since, bein bi molecular, its formation is retarded by the inversion of half of the terpene. The nitrosochloride melts at 115° C. (circa) and is a white pleasant-smelling powder. Alcoholic potash converts it into nitrosopinene, C1¢H1@NO. Bornylene, Cml-ln, derived from bicyclo-(1 - 2 - 2)-heptane, is prepared by heating bornyl iodide to 170° C. for several hours with a concentrated solution of alcoholic potash (G. /Vagner, Bef., 1900, 33, p. 2121), or by decomposition of the methyl esters of the l- and d-bornyl x ant hates, the former yielding d-borny1ene and the latter I-bornylene (L. Tschugaeff, Chem. Centralblatt, 1905, i., p. 94). Camphene, CIOHU, also a bicyclo-(1 - 2 - 2)~heptane derivative, is a constituent of the oils of citronella, camphor, ginger and of rosemary, and also of French and American oil of turpentine. It may be obtained by the action of sulphuric acid on pinene; by heating pinene hydro bromide or hydrochloride with sodium acetate or glacial acetic acid to 200° C.; or by heating bornyl chloride with aniline (O. Wallach, Bef., 1892, 25, p. 916). 'According to Konowalow it is best prepared by heating borneol with a diluted sulphuric acid (I - 2) for about 6-8 hours, between 60-100° C., with continual shaking, a yield of about 90 per cent. being obtained. The melting~ and boiling-points of camphene vary slightly according to the sources from which it is obtained, tlte' former being about 50° C. and the latter about 159-161° C. It is known in d-, I- and i- forms. It combines with hydrochloric acid to forma hydrochloride, which on reduction with sodium and alcohol yields camphene. Many different oxidation products may be obtained from camphene by varying the conditions of experiment (J. Bredt and W. jagelki, Ann., 1900, 310, p. 114; G. Wagner, Bef., 1890, 23, 2311; S. Moycho and F. Zienkowski, Ann., 1905, 340, p. 17; ?. E. Marsh and J. A. Gardner, Jour. Chem. Soc., 1891, 59, 'p. 648; 1396, 69, 1>~ 74)-Fenchene,

C10H1, ;, a bzcyclo-(I - 2 - 2)-heptane derivative, is not found in any naturally occurring products. The hydrocarbon may be obtained by the reduction of fenchone and elimination of water from the resulting fenchyl alcohol, or by the elimination of halogen hydride from the fenchyl halogen compounds (O. Wallach, Ann., 1892, 263, p. 145; 1898, 302, pp. 371 seq.). . The above bicycle-terpene hydrocarbons are most probably best represented by the following formulae (pinene is given above) z-HSC/CH ~ C(CH:) H C<CH - CH(CH;¢) H C/CH - C <CHz

C CH>cn 2 J: CH>cn 2 Q: CH, /cn.

C:H1 CzH1 CaH1

a-Thujene B-Thujene Sabincne

CH=~ C(CHz) ~ CH CH: ' CH- C:CHm CH2 - CH—C:CHQ | C(CHi)¢ 3 on. ctcnoi

CH; cn# 11 11. ~ cn - (crm. = H, ~ 3:1-1- 'Hi Bomylene Cainphene F enchene

ALCOHOL AND KETONE DERIVATIVES

Borneol (Borneo camphor), C,0H11OH occurs in the pith cavities of 'Dryobalanops camphora, and in the oils of spike and rosemary; esters are found in many fir and pine oils. It may be prepared by heating camphor with alcoholic potash (M. Berthelot, Ann., 1859. 12, p. 1563); or by reducing camphor in alcoholic solution with sodium (O. Wallach, Ann., 1885, 230, p. 225; Bertram and H. Walbaum, Jour. prak. Chem. 1894 (2), 49, p. 12). L. Tschugaelif (Chem. Centralblatt. 1905 i, p. 94) obtains pure ll-borneol as follows -lmpure d-borneol (containing isoborneol) obtained in the reduction of camphor is dissolved in xylene and converted into the sodium salt by metallic sodium. This salt is then turned into the xanthate, C191-117OCS2Na, which with methyl sulphate yields the corresponding methyl ester. Theunchanged isoborneol is removed by steam distillation, which also decomposes any methyl xanthate of isoborneol that may have been formed. The residue is crystallized and hydrolysed, when pure borneol is obtained. It behaves as a secondary alcohol, Nitric acid oxidizes it to camphor and when heated with potassium bi sulphate, it gives camphene. With phosphorus pentachloride it forms a bornyl chloride, identical with pinene hydrochloride.

Isobarneol is a tertiary alcohol which may be obtained by dissolving camphene in glacial acetic acid, adding dilute sulphuric acid and heating to 50-60° C. fcr a few minutes, the isobornyl acetate so formed being then hydrolysed (J. Bertram and H. Vialbaum, loc. c1t.). It crystallizes in leaflets, which readily sublime. Chromic acid oxidizes it to camphor.

Thujone (tan acetone), C10H16O, is found in many essential oils. Oil of thuja contains chiefly a~-thujone, and oil of tansy chiefly B-thujone. Oil of artemisia and oil of sage contain a mixture of the two, whilst oil of absinthe contains principally the 13-variety. The two forms may be obtained by fractional distillation of the oils, followed by at fractional, crystallization of their semicarbazones from methyl alcohol. a-Thujone is laevo-rotatory and when warmed with, alcoholic potash it is partially converted into B-thujone. Sodium in the presence of alcohol reduces it to thujyl alcohol, which on re-oxidation is converted into,8-thujone. The B-form is dextro-rotatory and is partially converted into the a-variety by alcoholic potash. When heated to 280° thujone is transformed into the isomeric carvotanacetone (A6-terpenone-2). On boiling with ferric chloride it yields carvacrol. Hott dilute sulphuric acid converts it into isothujone (dimethyl-1 - 2-isopropyl-3-cyclopentene-1»one-5). Thujone behaves as a saturated compound

and forms a characteristic tribromide. When heated with zinc chloride it yields hydropseudocumene. According to F. W. Semmler (Ben, 1900, 33, p. 275; 1903, 36, p. 4367) it is to be considered as a methyl-2-isopropyl-5-bi¢:yclo-(0 - 1 ~ 3)-hexanone-3. Carane, CIOHIGO, is a trim ethyl-3 - 7 - 7-bicycle-(0 - 1 - 4)-hep tan one-2, obtained by acting with alcoholic potash on dihydrocarvone hydro bromide (A. v. Baeyer, Ber., 1896, 29, pp. 5, 2796; 1898, 31, pp. 1401, 2067). It is a colourless oil, having the odour of camphor' and peppermint, and boiling at 210° C. It is known in d~, l-, and i-forms. It does not combine with sodium bisulphite. When heated it is transformed into carve none. It is stable to cold potassium permanganate solution, but on heating gives a dibasic acid, caronic acid, C5Hg(CO2H)2, which Baeyer suggested was a gem-dimethyltrimethylene-I - 2-dicarboxylic acid. This was confirmed by W. H. Perkin, junr. (Jour. Chem. Soc., 1899, 75, p. 48) who synthesized the acid from dimethylacylic ethyl ester. This ester with ethyl malonate yields ethyldimethylpropanetricarboxylic ester, which on hydrolysis and subsequent heating is converted into /SB-dimethyl glutaric acid. The u.-bromdirrethyl ester of this acid when heated with alcoholic potash yields cisand trans-caronic acids. Eucarvone, CWHMO, is a tri1nethy1 3-7-7-bicyclo-(0°I-4)-heptene-3-one-2. O. Nallach (A nn., 1905, 339, p. 94) suggests that the ketone possesses the structure of a trim ethyl-1 - 4 - 4-cycloheptadiene-5 - 7-one-2. Phosphorus pentachloride converts it into 2-chlorcymene (A. Klages, Bef., 1899, 32, D- 2558>-Camphor,

C101-LSO, is a trim ethyl-1 - 7 - 7-bicyclo-(1 - 2 - 2)-hep tan one-2. The d-variety is found in the camphor tree (Laurus camphora), from which it may be obtained by distillation in steam. The I-variety is found in the oil of Matricaria. parthen-ium. It crystallizes in transparent prisms which possess a characteristic odour, sublimes readily and is easily soluble in the usual organic solvents. It boils at 209° C. and melts at 176° C. (circa). The d-form may also be obtained by the distillation of calcium homo camphor ate (A. Haller, Bull. Soc. Chim., 1896 (3), 15, p. 324). When heated with phosphorus pent oxide it yields cymene, and with iodine, carvacrol. Nitric acid oxidizes it to camphoric acid, CgH;4(CO2H)2, camphoronic acid, CQHUOG, and other products. It forms an oxime with hydroxylamine which on dehydration ields a nitrile, from which by hydrolysis carnpholenic acid, C9H15C]OqH, is obtained It combines with aldehyde's to form alkylidene compounds, and yields oxymethylene compounds when subjected to the “ Claisen " reaction, It does not combine with the alkaline bisulphites. It is readily substituted by chlorine and bromine; and with fuming sulphuric acid forms a camphor sul honic acid. Sodium reduces tt, in alcoholic solution, to borneol. When heated with sodium formate to 120° C. it is converted into bornylamine. Caro's acid converts it into campholid, and a compound C101-l;¢O¢ (A. v. Baeyer and V. Villiger, Bef., 1899, 32, p. 3630). When heated with concentrated sulphuric acid to 105-110° C. it yields carve gone and 4-aceto-1 - 2-xylol (J. Bredt, Ann., 1901, 314, p. 371 .