Z-Menthol

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. 

Mesitylene, production from acetone, 1 164 Mesityl oxide, 14 589-590 characteristics of, 16 337 hydrogenation, 16 337-338 hydrogen peroxide treatment of, 16 338 Z-menthol from, 24 520 production of, 16 336-337 production from acetone, 1 164, 174 Mesogenic diols, 25 460 Mesogenic molecules, solids of, 15 82 Mesogens, 24 53, 54 Mesomixing, 16 683 Mesomorphic behavior, 24 53-54 Mesomorphic phase transitions, 15 102 Mesomorphism, 15 81. See also Liquid crystalline materials Mesophase pitch-based carbon fiber, 26 734-735... 

Piperitone, Z-menthol from, 24 522—523 Pipe still furnaces, 18 646 Pipe taps, 11 658-659 Piping... 

N-methyl derivative resulted in oxidation of the ligand with concomitant reduction of Co (III) to Co (II). The preparation of tris (benzohydroxa-mato) chromium (III), Cr(benz)3, was successful and resulted in the separation and characterization of its two geometric isomers (2). The half-lives for isomerization of these complexes near physiological conditions is on the order of hours. To facilitate the separation of all four optical isomers of a simple model tris (hydroxamate) chromium (III) complex, we prepared (using Z-menthol as a substituent) the optically active hydroxamic acid, N-methyl-Z-menthoxyacethydroxamic acid (men). This resulted in the separation of the two cis diastereoisomers of tris(N-methyl-Z-menthoxyacethydroxamato) chromium (III) from the trans diastereoisomers and their characterization by electronic absorption and circular dichroism spectra. 

FEMA No. 2665 3-p-Menthanol (NOTE /-Menthol is obtained from natural sources or by synthetic processes t/Z-Menthol is produced synthetically)... 

The simple alcohols whose trityl ethers have been prepared by treatment with trityl chloride and pyridine include, in addition to primary alcohols, 2-propanol, cyclohexanol, Z-menthol, d-borneol, and cholesterol. Trityl ethers involving the secondary hydroxyl group in glycerol are also known. - There can be no doubt, therefore, that secondary as well as primary hydroxyl groups react with trityl chloride in pyridine. 

Again it should be emphasized that this mechanism represents an oversimplification of the actual course of the reaction of nitrous acid with aliphatic amines (see p. 40). Htickel and Wilip24 have found, for example, that in aqueous solution Z-menthylamine (XXXIX) is transformed with no inversion or racemization into Z-menthol (XL). When the reaction is carried out in aqueous alcohol, however, the ether which is formed is partially racemized (XLI and XLII). The formation of a... 

A report describes the stereoretentive chlorination of cyclic alcohols with thionyl chloride and TiCl4. Evidence suggests formation of a nonplanar carbocation and frontside attack of the chloride nucleophile. The proposed mechanism is supported by product studies and DFT calculations. The studies include stereoselective chlorinations of Z-menthol and cholestanol derivatives. 

The extent to which a given dose of a menthol is conjugated with u-curonic acid also depends on the isomer fed. Williams (440) has own that menthols of the dextro configuration are excreted as glucuronosides to a greater extent than the Z-menthols. This behavior has been used by Williams (441, 442) for the optical resolution of cZZ-menthol and dZ-isomen-thol. 

The reduction of Z-menthone or inverted d-menthone yielded, together with ordinary menthol, a d-isomenthol melting at 78° to 81° C. [a] =... 

TEMPO has been structurally modified to bring about new selectivities. Highly efficient anionic water-soluble TEME<), oil-in-water nanoemulsion containing TEME for oxidation of alcohols and a waste-free system were developed. Especially, the sterically less crowded azabicyclo-Af-oxyls oxidized /-menthol to Z-menthone with much higher efficiencies than TEME O (equation 23). ... 

CioHigO, Mr 154.25, pure (-)-isopulegol [89-79-2], Z>/>ikPa 74 °C, df 0.9062, 1.4690, [q ]d - 23.6°. Like menthol, isopulegol has three asymmetric carbon atoms and, therefore, four stereoisomers, each occurring as a pair of optically active antipodes. 

Although various transition-metal complexes have reportedly been active catalysts for the migration of inner double bonds to terminal ones in functionalized allylic systems (Eq. 3.2) [5], prochiral allylic compounds with a multisubstituted olefin (Rl, R2 H in eq 2) are not always susceptible to catalysis or they show only a low reactivity [Id]. Choosing allylamines 1 and 2 as the substrates for enantioselective isomerization has its merits (1) optically pure citronellal, which is an important starting material for optically active terpenoids such as (-)-menthol, cannot be obtained directly from natural sources [6], and (2) both ( )-allylamine 1 and (Z)-allylamine 2 can be prepared in reasonable yields from myrcene or isoprene, respectively, The ( )-allylamine 1 is obtained from the reaction of myrcene and diethylamine in the presence of lithium diethylamide under Ar in an almost quantitative yield (Eq. 3.3) [7], The (Z)-allylamine 2 can also be prepared with high selectivity (-90%) by Li-catalyzed telomerization of isoprene using diethylamine as a telomer (Eq. 3.4) [8], Thus, natural or petroleum resources can be selected. 

Frankland and Price 17 were the first to attempt the resolution of alcohols (and acids) by fractional crystallization of their solid esters. The isomeric solid esters formed from Z-s-butylcarbinol and di-dibenzoyl-glyceric acid failed to separate on crystallization the corresponding di-alcohol-i-acid ester was liquid. Marckwald and McKenzie 18-19 effected partial resolutions of dl-mandelic acid and related acids with 1-menthol and d-bomeol, and of di-2-octanol with d-tartaric acid, but did not develop a satisfactory method for resolving alcohols. Later investigators, however, have employed the following resolving agents in several more or less successful resolutions of certain alcohols (a) i-menthyl isocyanate, (6) d-camphoric acid, (c) d- or i-mandelic acid, (d) d- or... 

Pure d-menthyl-Z-menthoxyacetate is hydrolyzed by refluxing for an hour with 1.2 mole equivalents of 5-10% ethanolic potassium hydroxide. (More vigorous hydrolysis is inadvisable since 1-menthol may thus be formed from the resolving agent by rupture of the ether linkage.) The mixture is almost neutralized to phenolphthalein with hydrochloric acid and is distilled with steam to remove first the ethanol and then the menthol. The menthol is conveniently extracted with benzene and purified by distillation under reduced pressure. It has b.p. 97-99°/10 mm., 215-2167760 mm. m.p. 42° and [aft0 + 49.5°(c = 2, 95% ethanol). The yield in this step is 80-85%. 

ACETYLENIC ETHERS FROM ALCOHOLS AND THEIR REDUCTION TO Z-AND E-ENOL ETHERS PREPARATION OF 1-MENTHOXY-1-BUTYNE FROM MENTHOL AND CONVERSION TO (Z)-AND (E)-1-MENTHOXY-1 -BUTENE ([Cyclohexane, 2-(1 -butynyloxy)-4-methyl-1 -(1 -methylethyl)- [1S-(1a,2p,4p)]-], end [[[Cyclohexane, 2-(1-butenyloxy)-4-methyl-1-(1-methylethyl)-, [1S-[1a,2P(Z),4p]]- and [lS-[1 ,2p(E),4P]]-)... 

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