ALCOHOL AND KETONE

This article appears in Volume V26, Page 650 of the Encyclopedia Britannica.

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ALCOHOL AND KETONE DERIVATIVES
Borneol (Borneo camphor), C1oH17OH occurs in the pith cavities of Dryobalanops camphora, and in the oils of spike and

rosemary

ROSEMARY

; esters are found in many fir and pine oils. It may be prepared by

heating

HEATING

camphor with alcoholic potash (M. Berthelot, Ann., 1859, 12, p. 363) ; or by reducing camphor in alcoholic solutionwith sodium (O. Wallach, Ann., 1885, 230, p. 225; J.

Bertram

BERTRAM, CHARLES (1723–1765)

and H. Walbaum, Jour.

peak

PEAK, THE

. Chem. 1894 (2), 49, p. 12). L. Tschugaeff (Chem. Centralbtatt. 1905 i , p 94) obtains pure d-borneol as follows.Impure 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, CIOH17OCS2Na, which with methyl sulphate yields the corresponding methyl ester. The unchanged isoborneol is removed by steam

distillation

DISTILLATION (from the Lat. distillare, more correctly destillare, to drop or trickle down)

, 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 bisulphate, it gives camphene. With phosphorus pentachloride it forms a bornyl chloride, identical with pinene hydrochloride.
Isoborneol is a tertiary alcohol which may be obtained by dissolving camphene in glacial acetic acid, adding dilute sulphuric acid and

heating

HEATING

to 50-6o C. fcr a few minutes, the isobornyl acetate so formed being then hydrolysed (J.

Bertram

BERTRAM, CHARLES (1723–1765)

and H. Walbaum, loc. cit.). It crystallizes in leaflets, which readily sublime. Chromic acid oxidizes it to camphor.
Thujone (tanacetone), C10H18O, 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 )3-variety. The two forms may be obtained by fractional

distillation

DISTILLATION (from the Lat. distillare, more correctly destillare, to drop or trickle down)

of the oils, followed by a fractional, crystallization of their semicarbazones from methyl alcohol. a-Thujone is laevo-rotatory and when warmed with alcoholic potash it is partially converted into /3-thujone. Sodium in the presence of alcohol reduces it to thujyl alcohol, which on re-oxidation is converted into l-thujone. The fl-form is dextro-rotatory and is partially converted into the a-variety by alcoholic potash. When heated to 28o thujone is transformed into the isomeric carvotanacetone (A6-terpenone-2). On boiling with ferric chloride it yields carvacrol. Hot dilute sulphuric acid converts it into isothujone (dimethyl-i . 2-isopropyl-3-cyclopentene-I-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 (Bee., 1900, 33, p. 275; 1903, 36, p. 4367) it is to be considered as a methyl-2-isopropyl-5-bicyclo-(o . I 3)-hexanone-3.
Carone, C1oH160, is a trimethyl-3 . 7 7-bicyclo-(o . I 4)-heptanone-2, obtained by acting with alcoholic potash on dihydrocarvone hydrobromide (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 carvenone. It is stable to cold potassium permanganate solution, but on heating gives a dibasic acid, caronic acid, C5H8(CO2H)2, which Baeyer suggested was a gem-dimethyltrimethylene-r 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 t913-dimethyl glutaric acid. The a-bromdirrethyl ester of this acid when heated with alcoholic potash yields cis-, and trans-caronic acids. Eucarvone, C1oH1,O, is a trimethyl-3.7.7-bicyclo-(0I.4)-heptene-3-one-2. O. Wallach (Ann., 1905, 339, p. 94) suggests that the ketone possesses the structure of a trimethyl-r .4 4-cycloheptadiene-5 . 7-one-2. Phosphorus pentachloride converts it into 2-chlorcymene (A. Klages, Ber., 1899,
32, p. 2558).
Camphor, C1oH16O, is a trimethyl-r . 7 . 7-bicyclo-(I 2 2)-heptanone-2. The d-variety is found in the camphor tree (Laurus camphora), from which it may be obtained by distillation in steam. The l-variety is found in the oil of Matricaria parthenium. 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 homocamphorate (A.

Haller

Bull

. Soc. Chim., 1896 (3), 15, p. 324). When heated with phosphorus pentoxide it yields cymene, and with iodine, carvacrol. Nitric acid oxidizes it to camphoric acid, C8H14(CO2H)2, camphoronic acid, C9H1306, and other products. It forms an oxime with

hydroxylamine

HYDROXYLAMINE, NH2OH

which on dehydration yields a nitrile, from which by hydrolysis carnpholenic acid, C9HISCO2H, is obtained It combines with aldehydes 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 sulphonic acid. Sodium reduces it, in alcoholic solution, to borneol. When heated with sodium formate to 12o C. it is converted into bornylamine.

Caro

CARO, ANNIBALE (1507-1566)
CARO, ELME MARIE (1826-1887)

's acid converts it into campholid, and a compound C10H1E0, (A. v. Baeyer and V. Villiger, Ber., 1899, 32, p. 3630). When heated with concentrated sulphuric acid to 105-110 C. it yields carvenone and 4-aceto-r 2-xylol (J. Bredt, Ann., 1901, 314, P. 371).

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