Pinene Nitrosochloride

Optically inactive a-pinene can be obtained by heating a-pinene nitrosochloride with aniline, It has the following characters —... 

In the preparation of the nitrosochloride, Wallach proposed to use pinene in glacial acetic acid and amyl nitrite. Ehestadt has recently proposed the following method, which is very simple and yields excellent results The pinene (or oil of turpentine) is diluted with its own volume of ether, the solution cooled with ice, and the gas generated hy dropping a saturated solution of sodium nitrite into concentrated hydrochloric acid passed through the solution. Fine crystals of pinene-nitrosochloride soon commence to separate out. Schimmel Co. obtained the following yields of nitrosochloride by the methods quoted —... 

Nitroso-pinene is obtained from pinene-nitrosochloride by the action of alcoholic potash,... 

Nitroso-pinene may be prepared for identification purposes as follows To a solution of 12 grams of sodium in 30 c.c. of 90 per cent, alcohol, 100 grams of pinene-nitrosochloride are added. The mixture is boiled on a water-bath, under a reflux condenser, until the reaction is complete. Water is added, the-clear solution filtered from insoluble impurities, and the filtrate poured into excess of acetic acid. The nitroso-pinene separates as an oil which solidifies to a yellowish mass in a few days. This is broken up, washed with water, and dried on a porous plate. It can be recrystallised from acetic ether, when it is obtained in the pure condition, and then melts at 132°. 

Pinene-nitrosochloride forms a series of compounds with various bases, such as propylamine, amylamine, benzylamine, etc., known as pinene-nitrolamines. If two molecules of benzylamine in alcoholic solution be allowed to act on one molecule of pinene-nitrosochloride, pinene nitrol-benzylamine separates on the addition of water, and on recrystallisation from a mixture of ether and alcohol, forms beautiful... 

C, b.p. 156 C. The most important of the terpene hydrocarbons. It is found in most essential oils derived from the Coniferae, and is the main constituent of turpentine oil. Contains two asymmetric carbon atoms. The (- -)-form is easily obtained in a pure state by fractionation of Greek turpentine oil, of which it constitutes 95%. Pinene may be separated from turpentine oil in the form of its crystalline nitrosochloride, CioHigClNO, from which the ( + )-form may be recovered by boiling with aniline in alcoholic solution. When heated under pressure at 250-270 C, a-pinene is converted into dipentene. It can be reduced by hydrogen in the presence of a catalyst to form... 

It is obtained from American turpentine as dextro-o-pinene, or from French turpentine as laevo-a-pinene. It is also obtained in a very pure form as dextro-a-pinene from Greek oil of turpentine. Optically inactive o-pinene can be obtained by regeneration from the nitrosochloride. The purest specimens of a-pinene yet obtained have the following characters —... 

It yields a crystalline hydrochloride melting at 130° to 131°. This compound is much more easily volatilised than pinene hydrochloride. With chlorine it yields a dichlor-firpene hydrochloride, whilst pinene yields no similar compound. It also yields a crystalline hydrobromide melting at 102°. No crystalline nitrosochloride has been prepared. The melting... 

Origanene yields a crystalline nitrosochloride, melting at 91° to 94°, and a nitrolpiperidine melting at 198°. These derivatives are prepared in the same manner as the corresponding compounds of pinene (q.T.). 

Interestingly, the two enantiomers of earvone have different characteristic odors and flavors, suggesting that chirality plays an important role in organoleptic function [1], Synthetic /-can-one (20) is produced on an industrial scale either from (/-limonene (17) (Scheme 6) or from a-pinene. The conversion of 17 into 20 is accomplished in tlrree steps through the intermediates (/-limonene nitrosochloride (24) and /-carvoxime (25), with greater than 60% overall yield (Scheme 6) [35]. 

R,5S-a-Pinene [7785-70-8] M 136.2, b 61 /30mm, 156.2 /760mm, df 0.858, n f 1.4634, ng 1.4658, [a]g +51 (neat) It is isomerised by heat, adds and certain solvents. It should be distilled under reduced pressure under nitrogen and stored in the dark. It has been purified via the nitrosochloride [Waterman et al. Reel Trav Chim, Pays-Bas 4S 1191 7929]. For purification of optically active forms see Lynn [7 Am Chem Soc 91 361 7979]. 

The oil has been exhaustively examined hy Schimmel Co. After repeated fractionation they succeeded in obtaining 11 grms. of a body with boiling-point 158 to 168 and an odour of pinene. Treated with nitrosylchloride a very small quantity of a nitrosochloride was obtained, of which the benzylamine-combination melted at 120 to 123 . The presence of a-pinene could be more readily proved by oxidation into active d-pinonic acid. The acid melted at 68 to 69 and was identical with d-pinonic acid from Greek oil of turpentine. It follows that the oil contains i- and d-a-pinene. 

Chace points out that the nitrosochlorides of pinene and of limonene crystallise in different forms, and makes use of this property to detect pinene. For this purpose he distils, in a Ladenburg flask, 5 c.c. from 50 c.c. oil, and from this he prepares the nitrosochloride with the use of ethyl nitrite according to Wallach s method. The mixture is left for fifteen minutes in a freezing mixture the crystals which separate off are then collected, washed with 50 c.c. 95 per cent, alcohol, the mother-... 

The presence of the small amount of dacrydene still remaining with the pinene fraction, raised the inelting-jioint of the nitrosochloride pre-... 

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