1.1- Nitrosochlorides

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... 

Limonene (+15) is an important raw material for producing (-)-carvone [6485-40-1]. The process uses nitrosyl chloride and proceeds via nitrosochloride and oxime (78,79). The (-)-carvone (40) is found as the main component of spearmint oil and the (+)-carvone produced from (—)-limonene has the characteristic odor of diU. 

Should be distd under reduced pressure under nitrogen and stored in the dark. Purified via the nitrosochloride [Waterman et al. Reel Trav Chim Pays-Bas 48 1191 7929]. For purification of optically active forms see Lynn [J Am Chem Sac 91 361 1919]. Small quantities (0.5mL) have been purified by GLC using helium as carrier gas and a column at 90 packed with 20 wt% of polypropylene sebacate on a Chromosorb support. Larger quantities were fractionally distd under reduced pressure in a column packed with stainless steel gauze spirals. Material could be dried with CaH2 or sodium, and stored in a refrigerator CaS04 and silica gel were not satisfactory because they induced spontaneous isomerisation. [Bates, Best and Williams 7 C/iem Soc 1521 7962.]... 

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 —... 

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... 

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... 

Both limonenes yield nitrosochlorides, Cj Hj NOCl, each of which can be separated into two modifications. There are thus four limonene nitrosochlorides they are known as the a- and /3- varieties of the dextro-and Zdew-rotatory forms of the terpenes. The a- and /3- forms, however, yield the same carvoxime on treatment with alcoholic potash. 

Here, as in every other case, the only difference between the derivatives of the two limonenes is that they are equally active optically in the opposite directions, and differ in the usual way in crystalline form. The nitrosochlorides, on boiling with alcoholic potash, yield nitroso-limonenes, CjdHjjNO. These are identical with the two carvoximes, and their constitution is probably Cj Hj. NOH. They both melt at 72° The carvoxime prepared from deicfro-limonene-nitrosochloride is faew-rotatory, whilst that from faew-limonene-nitrosochloride is dextro-rotatory. 

For the preparation and separation of the limonene nitrosochlorides the following method should be employed —... 

Five parts of the terpene, 7 of amyl nitrite, and 12 of glacial acetic acid are mixed and cooled with ice and salt, and a mixture of 6 parts of hydrochloric acid and 6 parts of glacial acetic acid added in small quantities at a time. Five parts of alcohol are then added and the mixture allowed to stand in a freezing mixture for a itime. A mass of crystals separates, which consists of the crude nitrosochlorides. This is filtered off and washed with alcohol. When perfectly dry 100 grams of the crystals are digested with 200 c.c. of chloroform for a few moments and at once filtered. The chloroform dissolves a-nitrosochloride, which is precipitated by the addition of excess of methyl alcohol. The crude compound is filtered off, dried and digested with anhydrous ether for... 

The portion of the mixture of crude nitrosochlorides which was not dissolved by chloroform consists of crude yS-nitrosochloride. This is dissolved by shaking with ten times its weight of chloroform. The solution is then filtered and methyl alcohol added and the precipitate filtered off, washed with ether, and dried. The dried compound is dissolved in ether and on evaporation of the solvent pure )8-nitrosochloride separates. This body melts at 100°. 

According to Wallach the nitrosochlorides are physical isomerides of the formula —... 

Very characteristic derivatives are obtained by the action of organic bases on the limonene nitrosochlorides. If d-a-limonene nitrosochloride be so treated, two nitrolamines are obtained, a-nitrolamine (dextro-rotatory), and /S-nitrolamine (laevo-rotatory). If d-)8-limonene nitrosochloride be treated in the same manner, exactly the same reaction products are obtained. If, on the other hand f-a-nitrosochloride or f-)8-nitrosochloride be treated in the same manner, a mixture of a-nitrolamine (laevo-rotatory) and )8-nitrolamine (dextro-rotatory) is obtained. 

Forster and van Gelderen have prepared a characteristic nitro-derivative of dipentene by treating dipentene nitrosochloride with sodium azide.. The resulting body, C (,H 5(NOH)N3, dipentene nitroso-azide. melts at 72° to 73°. The corresponding active limonene derivatives melt at 52° to 53°. 

In order that there might be no doubt as to the identity of the synthetical product, it was converted into the nitrosochloride, C,oH, 0, NOCl (melting-point 122°), and phenylurethane, Cj Hj-O. CO. NH. C H (melting-point 113°), and these were compared with specimens made from ordinary terpineol, with the result that the preparations obtained from the two sources were found to be absolutely identical. 

Sylvestrene nitrosochloride, CjoHj,. NOCl, is prepared from pure sylvestrene, regenerated from the dihydrochloride in the following manner Four volumes of the terpene are dissolved in six of amyl nitrite and five volumes of strong hydrochloric acid are added, with constant shaking. The heavy oil which separates is shaken with a little ethyl alcohol, when it solidifies, and can be purified by dissolving it in chloroform and precipitating it with petroleum ether. It is finally recrystallised from methyl alcohol, when it melts at 106° to 107°. 

No crystalline nitrosochlorides have, so far, been prepared from a-phel-landrene. 

This aldehyde is identical with the naturally occurring phellandral, an aldehyde found in oil of water fennel. If the nitrosochloride of /3-phellandrene be decomposed by acetic acid, dehydrocuminic aldehyde and carvacrol result. 

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.). 

It forms a nitrosochloride melting sharply, but with decomposition, at 120° to 121°. It has been named dacrydene. 

Santene forms a nitrosochloride, prepared in the usual manner, melting at 109° to 110°, and a nitrosite melting at 125°. It also forms a hydrochloride melting at 80° to 81°. By hydration with sulphuric and acetic acids it yields an alcohol C HjjOH, which is termed santenol (isosantenol, nor-bomeol). This body melts at 97° to 98° and boils at 195° to 196°. 

The nitrosochloride, Cj5Hjj4. NOCl, prepared in the usual manner, is a white powder melting with decomposition at 96° to 97°. 

The former of these bodies gave a yield of 20 per cent, of a nitrosochloride and 8 2 per cent, of a blue nitrosite. The second gives only a very small quantity of nitrosochloride and only 0-5 per cent, of nitrosite. 

Caryophyllene nitrosochloride, (CjgHgJjN OoCL, is obtained when a mixture of the sesquiterpene, alcohol, ethyl acetate, and ethyl nitrite is cooled in a freezing mixture, and then treated with a saturated solution of hydrochloric acid in alcohol. The reaction mass is allowed to stand on ice for an hour and is then exposed to sunlight. Thus prepared it melts at about 158° to 163°, and can be separated into two compounds, one being that of a-caryophyllene and the other that of yS-caryophyllene Deussen s sesquiterpenes of natural caryophyllene from clove oil), a-caryophyllene nitrosochloride melts at 177", and /3-caryophyllene nitrosochloride at 159°. They can be separated by fractional crystallisation. The corresponding a-nitrolbenzylamine melts at 126° to 128°, and the /3-nitrolbenzylamine at 172° to 173°. The bimolecular formula given above is probable but not certain. 

Nitroso-caryophyllene, CjgHjgNO, is prepared by splitting off hydrochloric acid from the corresponding nitrosochloride, by means of sodium methylate. a-Nitrosocaryophyllene melts at 116° and is optically inactive (as is the a-nitrosochloride), and yS-nitrosocarj-ophyllene melts at 120° to 121° and has a specific rotation -H 61-77° (as against — 98 07°for the /3-nitrosochloride). 

This body has been termed by Deussen isocaryophyllene. It yields two nitrosoohlorides, a-isocaryophyllene nitrosochloride melting at 122°, and yS-isooaryophyllene nitrosochloride melting at 146°. 

Deussen considers that the nitrosate above described is identical with that of a-caryophyllene, and that the nitrosochloride is identical with that of the same sesquiterp ene. He therefore considers that iinmulene is, at all events i in greater part, actually a-caryophyllene. 

No crystalline hydrochlorides eould be obtained from either santalene. tt-Santalene forms a liquid dihydrochloride of optical rotation -n 6°, when dry hydrochloric acid is passed through its ethereal solution. It also forms a crystalline nitrosochloride melting with decomposition at 122°, and a nitrol-piperidide melting at 108° to 109°. /3-santalene forms corresponding compounds, the dihydrochloride having a rotatory power -H 8°. It forms, however, two isomeric nitrosochlorides, CigHj NOCl. They may be separated by fractional crystallisation from alcohol. One melts at 106°, the other at 152°. The corresponding nitrol-piperidides melt at 105° and 101° respectively. 

It does not yield a solid nitrosochloride, nor a nitrosite, hut it yields A crystalline hydrochloride, melting at 117° to 118°, which is identical with cadinene hydrochloride. Semmier considers copaene to have the iormula—... 

Terpineol nitrosochloride, Cj Hj-OH. NOCl, is, perhaps, the most suitable derivative to prepare for the identification of terpineol. To a solution of 15 grams of terpineol in 15 c.c. of glacial acetic acid, 11 c.c. of ethyl nitrite are added. The mixture is cooled in ice, and 6 c.c. of hydrochloric acid mixed with 6 c.c. of glacial acetic acid are added drop by drop, with continual shaking. Care must be taken to avoid a rise in temperature. When the reaction is compdete, water is added to pjre-cipitate the nitrosochloride. The oily liquid soon solidifies and may be recrystallised from boiling acetic ether or from methyl alcohol. Ter-... 

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