Dextro-rotatory

In this preparation, the ( + ) or dextro-rotatory (natural) camphor or the ( ) or racemic (synthetic) camphor can be used. Perform the oxidation in a fume-cupboard. 

Sucrose is dextro-rotatory. Fructose shows a laevo-rotation greater in magnitude than the dextro-rotation shown by glucose. Hence as the hydrolysis of sucrose proceeds, the dextro-rotation gradually falls to zero and the solution finally shows a laevo-rotation. This hydrolysis is therefore sometimes called inversion and so the enzyme which catalyses the reaction is known as " invertase. Its more systematic name is, however, sucrase. 

IV-Methyllaurotetaninc, C20H23O4N. This alkaloid was obtained by Spath and Suominen from Litsea citrata. It distils at 205-15° (air-bath temperature) urder a pressure of 0-01 mm. and is dextro-rotatory. Diazomethane converts it into glaucine and Hofmann degradation of the ethyl ether yields 3 5 6-trimethoxy-2-ethoxy-8-vinylphenanthrene, m.p. 140-1°, identical with that obtained from laurotetanine (see above). The alkaloid is therefore represented by formula II (NMe replacing NH). 

II spike oU be fcactiooally distilled (preferably in a flask as Ulna-trated (tig. 24), with the lowest bulb holding about 12.5 c.c.), using 50 e.e. lor the purpose, the first 10 per cent, obtained is nsually dextro-rotatory, and not diliering more than about 2° in rotation from the original oil. 

The best known oil of the. VoiKirda species is that known as America horse-mint oil, which is obtaLoed to the extent of about 1 per cent, from the herb. 1/oiKirdo pnnr.Lnta. The oil has a specific gravity from 0 930 to O iMO, and is either optically inactive or slightly dextro-rotatory. 

By oxidation of d- and Z-pinene of high rotatory power, Barbier and Grignard obtained the optically active forms of pinonic acid. Z-pinene from French turpentine oil (boiling-point 155 to 157 , od - 37 2 157 to 160 , tto - 32 3°) was oxidised with permanganate. From the product of oxidation, which (after elimination of the volatile acids and of nopinic acid) boiled at 189 to 195 under 18 mm. pressure, Z-pinonic acid separated out in long crystalline needles, which, after recrystallisation from a mixture of ether and petroleum ether, melted at 67° to 69 . The acid was easily soluble in water and ether, fairly soluble in chloroform, and almost insoluble in petroleum ether. Its specific rotation is [a]o - 90-5 in chloroform solution. Oximation produced two oximes one, laevo-rotatory, melting-point 128 and the other, dextro-rotatory, melting-point 189° to 191°. 

It is convenient to here mention the hydrocarbon verbenene, C,gH,4, on account of its relationship with pinene. It results from the action of acetic anhydride on verbenol, thei alcohol corresponding with the ketone, verbenone. So produced it is laevo-rotatory. The dextro-rotatory and racemic varieties are also known. The sesquiterpenes have the following characters when regenerated from their respective dibromides —... 

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. 

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. 

Sylvestrene is a well-recognised terpene, which is found in various turpentine and pine oils, but only in its dextro-rotatory form. Carvestrene is merely the optically inactive variety of sylvestrene, and is another instance of unfortunate nomenclature it should be properly called t-sylvestrene. 

Baker and Smith have isolated from the essential oil of the leaves of Phyllodadus Rhomboidalis a diterpene, which they have named phyllocladene It has the formula C2UH32, and melts at 95°. It is dextro-rotatory, its specific rotation being -t- 16-06°. 

The fraction of oil of cade boiling at 260° to 280° is converted into cadinene dihydrochloride by saturating its solution in dry ether with dry hydrochloric acid gas. The hydrochloride is separated, dried, and leorystallised, and the hydrochloric acid removed by heating it with aniline or with sodium acetate in glacial acetic acid. The liberated cadinene is rectified in a current of steam. Cadinene from oil of cade is highly laevo-rotatory, the dextro-rotatory variety being obtained from Atlas cedar oil and West Indian sandalwood oil. 

Faolini and Divizia have succeeded in partially resolving inactive linalol into its optically active isomers hut only to the extent of optical rotations of + 1° 70 and — 1° 60 respectively. Linalol was converted into its acid phthalate, and an alcoholic solution of this compound was treated with the equivalent quantity of strychnine. By fractional crystallisation the laevo-rotatory salt, yielding dextro-rotatory linalol, separates first, leaving the more soluble dextro-rotatory strychnine salt, which yielded laevo-rotatory linalol in the mother liquor. 

On oxidation with chromic acid in acetic acid solution, dihydrocarveol yields dihydrocarvone, which has a specific gravity 0 928 at 19°, and refractive index 1-47174. The dihydrocarvone from Zae o-dihydro-carveol is dextro-rotatory, and -vice versa. Its oxime melts at 88° to 89° for the optically active variety, and at 115° to 116° for the optically inactive form. 

When menthone is reduced there is found, in addition to menthol, a certain amount of isomenthol. This body melts at 78° to 81° and is slightly dextro-rotatory, its specific rotation being -f- 2°. 

Schimmel Co. attempted to acetylise the alcohol by means of acetic anhydride, but the reaction product only showed 5 per cent, of ester, which was not submitted to further examination. The bulk of the alcohol had been converted into a hydrocarbon, with loss of water. Ninety per cent, formic acid is most suitable for splitting off water. Gne hundred grams of the sesquiterpene alcohol were heated to boiling-point with three times the quantity of formic acid, well shaken, and, after cooling, mixed with water. The layer of oil removed from the liquid was freed fi-om resinous impurities by steam-distillation, and then fractionated at atmo.spheric pressure. It was then found to consist of a mixture of dextro-rotatory and laevo-rotatory hydrocarbons. By repeated fractional distillation, partly in vacuo, partly at ordinary pressure, it was possible to separate two isomeric sesquiterpenes, which, after treatment with aqueous alkali, and distillation over metallic sodium, showed the following physical constants —... 

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... 

The odour of the ester varies slightly, according as it is made from the dextro-rotatory or the laevo-rotatory variety of the alcohol. That of the former is rather fuller and deeper in its rose odour than that of the latter. Both esters blend excellently with the corresponding citronellols, and are very useful in preparing synthetic otto of rose. 

Carvone, CjjHj40, is the ketone characteristic of dill and caraway oils. It occurs in the dextro-rotatory form in these oils, and as laevo-carvone in kuromoji oil. 

Beckmann has examined the characters of the optically active men-thones. The oxidation of natural Z-menthol by chromic acid mixture yielded Z-menthone [a]n = - 28 5° which when treated with 90 per cent, sulphuric acid is converted into a d-menthone [ajn = 4- 28 1°, which, however, is not the optical antipode of the first it behaves as a mixture of d- and Z-menthone, but is more strongly dextro-rotatory than it would be if it were only a mixture of the two optical antipodes. 

The treatment of menthylamine by nitrous acid yielded a d-isomenthol still more strongly dextro-rotatory. A d-isomenthylamine hydrochloride, having a rotatory power of [a]o = -1- 17 7°, yielded a d-isomenthol having [a]o = + 25-6°. 

Until the work of Zavarin and Snajberk (1973a), the only chemical information available on the bristlecone pines was the report by Haagen-Smit et al. (1950) that the major component of P. longaeva (at that time referred to as P. aristata) turpentine was a-pinene and, interestingly, that the optical rotation of a-pinene from P. longaeva and southern specimens of P. balfouriana was dextro rotatory (h-26.12° and +23.72°, respectively), whereas that of northern specimens of P. balfouriana was levo rotatory (-10.23°). 

Enantiomers possess identieal physieal properties namely, melting point, boiling point, refraetive index, ete. They only differ with respeet to the rotation of plane polarised light. If one of the enantiomer is dextro rotatory, the other will be laevo rotatory. 

The arginine, as it occurs in the proteins, is the dextro-rotatory modification except in fibrin, from which both Kutscher and Cathcart have isolated the inactive form. 

Optically Active Dodecammino-hexol-tetra-cobaltic Salts.3— These salts may be resolved by means of bromo-camphor sulphonic acid. Dodecammino-hexol-tetracobaltic chloride is mixed with silver bromo-camphor sulphonate, whereby all the chlorine is precipitated as silver chloride and the solution treated with dilute acetic acid. The ilrst crop of d-bromo-camphor sulphonate is laevo-rotatory, that from 1-bromo-eamphor sulphonate dextro-rotatory. 

By hydrolysis of a dextro-rotatory 2-octyl nitrate in a neutral medium, this compound has been decomposed to yield a laevo-rotatory product containing 13% of 2-octanone and 87% of 2-octanol, the latter comprising 71% of (-)2-octanol and 29% racemate, i.e. 85.5 parts of laevo-rotatory and 14.5 parts of dextro-rotatory alcohol. 

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