Fenchyl

Up to this point no evidence was forthcoming that any oneoffthe fenchenes prepared was pure, as the optical rotation of nearly every specimen was different. Wallach i has, however, more recently prepared fenchene by treating fenchyl-amine with nitrous acid. The resulting terpenes were separated by fractional distillation into two main portions, one of which had the following characters —... 

Komppa and Eoschier now propose a revision of the nomenclature of the fenchene terpenes, Wallach s D-fenchene being termed a-fenchene, D-Z-fenchene becoming Z-o-fenchene, and D-d-fenchene becoming d-a-fenchene. The fenchene obtained by Bertram and Helle s method, by dehydrating fenchyl alcohol with potassium bisulphate, is now termed y8-fenchene. This nomenclature is certainly preferable as it contains no suggestion that the two bodies are identical in chemical constitution, nor is there any particular evidence that D-Z-fenchene and L-Z-fenchene are not the same actual terpene, and equally so in the case of D-d-fenchene and L-d-fenchene. 

Accepting the later nomenclature, y8-fenchene can be prepared almost free from the a- variety by heating fenchyl alcohol with KHSO4. After repeated fractionation over sodium, /8-fenchene has the following characters —... 

The chemistry of fenchyl alcohol, Cj HjgO, must be regarded as in a somewhat unsettled state, as questions of isomerism arise which are as yet unsolved. It was ori nally prepared by Wallach by reducing the ketone fenchone, a natural constituent of several essential oils, by means of sodium. Later he obtained it in fairly large quantities as a byproduct in the preparation of fenchone-carboxylic acid, by passing a current of C(X through an ethereal solution of fenchone in the presence of sodium. Fenchyl alcohol has, so far, been found in one essential oil only, namely, that of the root wood of Pinus palustris. 

Wallach gives the following characters for the laevo-rotatory fenchyl alcohol —... 

The naturally occurring fenchyl alcohol is optically inactive and melts at 33° to 35°, which agrees with the observations of Wallach, a mixture of the two optically active forms, each of which melted at 45°, melting at 33° to 35°. 

Pickard, Lewcock and Yates have prepared fenchyl alcohol by the reduction of laevo-rotatory. On conversion into its hydrogen phthalate and fractionally crystallising the magnesium and cinchonine salts, they obtained a fraction, which on saponification yielded Za w-fenchyl alcohol, having a specific rotation of - 15 5°, which is probably the correct value for this figure. 

Fenchyl alcohol yields a phenylurethane melting at 88° when prepared from the optically inactive alcohol, and at 82-5° when prepared from the optically active form. It yields fenchone on oxidation, which can be identified by its crystalline combinations (vide fenchone). 

Fenchyl alcohol has, according to Semmler, the following constitution —... 

When the terpene a-fenchene (isopinene) is hydrated by means of acetic and sulphuric acids, it yields an isomer of fenchyl alcohol, which is known as isofenchyl alcohol (q.v.), and which on oxidation yields iso-fenchone, as fenchyl alcohol yields fenchone. The two ketones, fenchone and isofenchone, are sharply differentiated by isofenchone yielding iso-fenchocamphoric acid, Cj Hj O, on oxidation with potassium permanganate, which is not the case with fenchone. According to Aschan,i the hydrocarbon found in turpentine oil, and known as /9-pinolene (or cyclo-fenchene—as he now proposes to name it), when hydrated in the usual manner, yields both fenchyl and isofenchyl alcohols, which on oxidation yield the ketones fenchone and isofenchone. According to Aschan the relationships of these bodies are expressed by the following formulae —... 

By reduction fenchone is converted into fenchyl alcohol, melting at 45°. The alcohol, however, has the opposite optical rotation to that of the ketone from which it is prepared. 

The volatile extract obtained from galbanum was principally composed of a-pinene (1), p-pinene (4), fenchyl acetate (30), y-cadinene (66), guaiol (77) and <7,v-guai-9-en-1 l-ol... 

Eugenol, ml08 Eugenol methyl ether, a84 Fenchone, t376 Fenchyl alcohol, t375 A -9/7-(2-Fluorenyl)acetainide, al3... 

Many papers from the patent literature on pyrethroids and juvenile hormones cannot be included in this Report. Papers have reported the synthesis and activity of monoterpenoid juvenoids, including geranyl pyridyl ethers " and geranyl alkyl ethers and amines and their epoxides. Further papers in this section include a report of the potent lung toxicity of perillaketone, the observation that the malodorous water contaminant 2-methylisoborneol has the l-R-exo configuration, and that fenchyl methyl L-aspartylaminomalonate is 2 x 10" times sweeter than sucrose. ... 

Fenchone [7787-20-4] containing a small amount of the (-)-isomer [4695-62-9] is prepared by dehydrogenation of (-)-fenchol. (-)-Fenchyl esters are obtained, along with other compounds, by addition of carboxylic acids to a-pinene. Hydrolysis of the esters yields (-)-fenchol. 

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