Menthol systems

Foss S, J Harder (1998) Thauera linaloolentis sp. nov. and Thauera terpenica sp. nov., isolated on oxygen-containing monoterpenes (linalool, menthol, and eucalyptol) and nitrate. System Appl Microbiol 21 365-373. 

The above system has been used for the reaction of EtjNH with myrcene to give a mixture of hydroamination products (53% yield) containing 80% of N,N-diethylgeranylamine [208], a key intermediate for the synthesis of industrially important monoterpenes [208, 209-211], including (-)-menthol (Tagasako process) [212]. 

Topical analgesics sometimes are used for mild pain or as an adjunct to systemic therapy. There are limited data to support the use of salicylate-containing rubefacients (e.g., methyl salicylate and trolamine salicylate) or other counterirritants (e.g., menthol, camphor, and methyl nicotinate) in OA.32 See Chap. 57 for more information on these products when used for musculoskeletal disorders. 

Figure 6.7 Helical columns based on a donor-acceptor system of atkoxytriphenylenes and menthol 3,5-dinitrobenzoates.

Thioanisolc. A system utilizing thio-anisole as an organic mediator was developed for the oxidation of secondary alcohols to ketones (Fig. 5 2-octanol to 2-octanone 99%, menthol to menthone 92%, cyclododecanol to cyclododecanone 75%) [43]. The use of 2,2,2-trifluoroethanol as a solvent in the mediatory system improved the yields [44]. 

An interaction between main olfaction and the trigeminal somatosensory system has been proposed to facilitate directional smelling. For carbon dioxide and menthol, human subjects were able to tell the odor direction in 96% of cases, while the results for hydrogen sulfide and vanillin were random (Kobal et ah, 1989). Rats can discriminate odor direction in one sniff (Rajan et ah, 2006). 

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). ... 

An early example of an MIP-QCM sensor was a glucose monitoring system by Malitesta et al. (1999). A glucose imprinted poly(o-phenylenediamine) polymer was electrosynthesized on the sensor surface. This QCM sensor showed selectivity for glucose over other compounds such as ascorbic acid, paracetamol, cysteine, and fructose at physiologically relevant millimolar concentrations. A unique QCM sensor for detection of yeast was reported by Dickert and coworkers (Dickert et al. 2001 Dickert and Hayden 2002). Yeast cells were imprinted in a sol-gel matrix on the surface of the transducer. The MIP-coated sensor was able to measure yeast cell concentrations in situ and in complex media. A QCM sensor coated with a thin permeable MIP film was developed for the determination of L-menthol in the liquid phase (Percival et al. 2001). The MIP-QCM sensor displayed good selectivity and good sensitivity with a detection limit of 200 ppb (Fig. 15.7). The sensor also displayed excellent enantioselectivity and was able to easily differentiate the l- and D-enantiomers of menthol. 

Mentha arvensis L. M. haplocalyx Briq. China Menthol, menthone, menthyl acetate.33 Stimulate gastrointestinal tract motility and central nervous system, dilate peripheral blood vessels. Increase sweat gland secretion. 

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. 

The first enantiomer-selective polymerization was performed with propylene oxide (172) as a monomer [245], The polymerization was carried out with a ZnEt2/(+)-bor-neol or ZnEt2/(-)-menthol initiator system. The obtained polymer was optically active and the unreacted monomer was rich in (S)-isomer. Various examples are known concerning the polymerization and copolymerization of 172 [246-251 ]. A Schiff base complex 173 has been shown to be an effective catalyst In the polymerization at 60°C, the enantiopurity of the remaining monomer was 9% ee at 50% monomer conversion [250],... 

Morimoto, EL, et al. 2002. In vitro skin permeation of morphine hydrochloride during the finite application of penetration-enhancing system containing water, ethanol and 1-menthol. Biol Pharm Bull 25 134. 

In other systems, a particular structure may be found as a mixture of diastereoisomers. Peppermint (Mentha x piperita Labiatae/Lamiaceae) typically produces (—)-menthol, with smaller amounts of the stereoisomers (+)-neomenthol, (+)-isomenthol, and (+)-neoisomenthol, covering four of the possible eight stereoisomers (Figure 5.16). Oils from various Mentha species also contain significant amounts of ketones, e.g. (—)-menthone, (+)-isomenthone, (—)-piperitone, or (+)-pulegone. The metabolic relationship of... 

Fontes et al. (1998b) studied the enantioselectivity of cutinase and found that it was very selective toward one enantiomer with an enantiomeric excess of almost 100%. They found that the enantioselectivity was very sensitive to changes in water content. Bornscheuer et al. (1992) studied hydrolysis, esterification, and transesterification in carbon dioxide to try to find the best method for producing enantiomerically pure substances in carbon dioxide. They found that the thermodynamically favored hydrolysis led to higher enantiomeric excess with less enzyme in the shortest time. Michor et al. (1996b) also examined more than one system to determine a better route to product and found that while the transesterification of -menthol was fast and resulted in high enantiomeric excess, resolution of -citronellol was not feasible. The reaction rate for the reaction of -citronellol was 10-20 times of that of -menthol, but was not selective. 

Other chemical sensations associated with the trigeminal ganglion include temperature sensations such as the coolness (35) associated with menthol and the heat associated with capsaisin. Oral sensations elicited by chemical solutions also include tactile sensations such as smooth, dry, or powdery, and such disagreeable sensations as pain. Some of these sensations may represent different degrees of activation of a single system or the activation of several separate systems. 

The relatively high optical purities obtained with the Rh-NMDPP system are particularly interesting from a practical viewpoint since the NMDPP ligand is prepared from an inexpensive, commercially available, chiral precursor, (-)-menthol (17). Tertiary phosphines chiral at phosphorus, on the other hand, are much less accessible and require a classic resolution step (see later discussion for details Section II. B). 

Reactions were carried out in the 140 ml reaction vessel. ( )-menthol and 200 mg of the enzyme peparation were placed in the reactor and the reactor connected to the system. The whole system was flushed with CO2 after which pressure and temperature were adjusted to 100 bar and 50°C. Water activity was set to the desired value by adding portions of water via the HPLC valve. The reaction was started by the addition of 1 ml of isopropenyl acetate once again via the HPLC valve. Final substrate concentrations were 20 mM menthol and 54 mM isopropenyl acetate. Stirring of the enzyme reactor was accomplished by a magnetic stirrer. In addition the reaction medium was pumped in a circle using a gear pump. The enzyme was retained in the enzyme reactor by a nylon membrane. Samples were taken via the HPLC-valve with a 500 pi sample loop, the content of which was expanded into hexane, and analyzed on a HP 5890 Series II gas chromatograph. 

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