Bornyl

Present in citronella and valerian oils, tur penline, ginger, rosemary and spike oils. It is produced artificially by the elimination of hydrogen chloride from bornyl chloride (artifi cial camphor) or from isobornyl chloride, by the dehydrogenation of borneol and isobor-neol and by the action of elhanoic anhydride on bornylamine. Chiral. 

Ordinary commercial camphor is (-i-)-cam phor, from the wood of the camphor tree. Cinnamonum camphora. Camphor is of great technical importance, being used in the manufacture of celluloid and explosives, and for medical purposes, /t is manufactured from pinene through bornyl chloride to camphene, which is either directly oxidized to camphor or is hydrated to isoborneol, which is then oxidized to camphor. A large number of camphor derivatives have been prepared, including halogen, nitro and hydroxy derivatives and sulphonic acids. 

An increasing number of examples of ring formation through 1,5-electrocyclization of appropriate carbanions are illustrated in Scheme 27. In the last example the use of a chiral alkoxide (R = menthyl or bornyl) results in the formation of chiral indolines with optical purities ranging from 17 to 31%. 

The specific gravity ol the crude oil at C. = 0 S705 rotation a = -(- 15-1 relractiTe index at23 C. = lAtHl. The saponification number is 2 4, equal to (l 84 per cent, of ester as bornyl or gemoyl acetate. 

Tt consists cliielly of f-plni ne and /-llmoiieuo, with a small amounl of bornyl acolatu. 

It is best prepared, however, by converting the alcohol, borneol, into bomyl chloride. The bornyl chloride is carefully dried and then gently warmed with an equal weight of aniline. The mixture is then heated to the boiling-point of aniline when the reaction, which is suddenly violent, 18 quickly completed. The reaction mass is neutralised by hydrochloric acid and distilled over in a current of steam. Gamphene is rapidly condensed and solidifies to a crystalline mass. 

In the same way bornyl and isobornyl chlorides react with milk of lime. But, whereas bornyl chloride gives an almost quantitative yield of... 

The purest laevo-bornyl formate examined had a specific gravity 1 016, optical rotation — 48° 56, refractive index 1-47121, and boiling-point 97° at 15 mm. pressure. The ester has the constitution... 

Bornyl Acetate.—The acetic acid ester is the most important of the series. It is a constituent of pine-needle and rosemary oils, and has a most fragrant and refreshing odour. It is prepared artificially by the action of acetic anhydride on borneol, in the presence of sodium acetate, or by the condensation of borneol with glacial acetic acid in the presence of a small amount of a mineral acid. It is absolutely necessary in the reproduction of any pine odour. It is a crystalline body, crystallising from peDroleum ether in rhombic hemihedric crystals melting at 29°. The optical activity depends on that of the borneol from which it has been prepared. It has the following characters —... 

It is soluble in 3 volumes of 70 per cent, alcohol. The commercial product is usually a mixture of dextro-rotatory and laevo-rotatory bornyl acetate. It should contain not less than 98 per cent, of ester, and... 

Bornyl Propionate.—The propionic acid ester of borneol closely resembles the acetic ester, but as is, of course, usual in homologous series, its odour is slightly different. It has the formula... 

Dextro-dihydroverbenol melts at 58° C. and boils at 218° C. it yields an acetic ester, the odour of which recalls that of bornyl acetate. Dextro-dihydroverbenone is produced by the oxidation of the above alcohol by means of chromic acid, or by the reduction of verbenone by means of hydrogen in presence of colloidal palladium. It boils at 222° C. (Djj 0-9685 [a]o + 52-1 9° 1-47535 molecular refraction 44 45) and gives... 

Geranjl, linalyl, and bornyl acetates Menthyl acetate (for peppermint oil) Geranyl tiglate (for roee-geranium oil) Santalyl acetate (for sandalwood oil) Sabinyl acetate (for savin oil). ... 

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