Solubility menthol

Comparing the undissolved essential oil with that which was dissolved in the waters, it is seen that the former is richer in esters, poorer in free menthol and total menthol, and richer in menthone than the second. In other words the relatively sparingly soluble constituents are esters and menthone, whilst menthol is particularly soluble. 

The earlier researches of Charabot have shown that the essential oil of the flowers is richer in menthone than the essential oil of the leaves. And it is in spite of a circulation of menthol, a soluble principle, from the leaf to the inflorescence, that this latter organ contains an essential oil particularly rich in menthone. It must therefore be that the menthol is there converted into menthone by oxidation. 

The differences in composition between the two essential oils examined show well, if they be compared with those which exist between the essential oils of the leaves and the inflorescences, that the distribution of the odorous principles between the leaf, the organ of production, and the flower, the organ of consumption, tends to take place according to their relative solubilities. But this tendency may be inhibited, or on the other hand, it may be favoured by the chemical metamorphoses which the substances undergo at any particular point of their passage or at any particular centre of accumulation. Thus, in the present case, some of the least soluble principles, the esters of menthol, are most abundant in the oil of the leaves, whilst another, menthone, is richest in the oil of an organ to which there go, by circulation, nevertheless, the most soluble portions. This is because this organ (the flower) constitutes the. medium in which the formation of this insoluble principle is particularly active. 

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). ... 

FIGURE 11. Headspace analysis of solutions of menthol [- -], carvone [- -] and cineole [-A-] in SLS (initial concentration, SLS=1.0%, flavorant=0.0075%) showing differences in release of flavor compounds according to their solubility in SLS micelles [Adapted from ref. 77]. 

Menthol 0.003-0.015% in suspensions, and syrups Cooling effect Sublimes easily above 25° C and composition of natural oil may vary with source Incompatible with thymol, phenol, camphor, and other excipients Slightly soluble in glycerin very soluble in alcohol... 

Optically pure, water-soluble macrocyclic TB tetraacid 104 has been examined as a receptor for terpenes. A H NMR study in an ND4C1/ND3 buffer at pD 9.0 in D20 showed that host 104 binds the isomeric menthols with reasonable selectivity [(-)-menthol Ka — 2.5 + 0.2 x 103M 3], ( + )-menthol Ka — 2.0 + 0.2 x 103 M ... 

Crude i-menthol is, obtained similarly from the strongly levorotatory fractions of the ester. It may be purified by esterification with d-menthoxyacetyl chloride and crystallization of the resulting mixture of esters. The i-alcohol-d-acid ester is then readily purified since it is the less soluble and also the more abundant component. Various other methods for purifying the partially active 1-menthol also may be used if desired. See references in Table III, p. 408). 

A number of articles have been written which concern the poor solubilities of products. Suspension cultures of Mentha produce menthol which has very low solubility in water due to its hydrophobicity, and this is considered to be a factor responsible for its low production in the suspension cultures. Cyclo dextrin has a hydrophobic cavity inside the molecule in which menthol can be captured and allow to form a stable complex. A suspension culture of Mentha piperita showed a 70% production enhancement in a medium contain-... 

Menthol (Fig. 1.19) is a monoterpene natural product obtained from peppermint oil. Typical of terpenoids, menthol is only slightly soluble in water and is soluble in most organic solvents. The trans arrangement of the methyl and isopropyl substituents on the cyclohexane... 

Mentha Arvensis Oil, Partially Dementholized, occurs as a colorless to yellow liquid with a characteristic minty odor. It is the portion of oil remaining after the partial removal of menthol, by freezing operations only, from the oil of Mentha arvensis var. piperascens Holmes (forma piperascens Malin-vaud) (Fam. Lamiaceae). It is soluble in most fixed oils, in mineral oil, and in propylene glycol. It is insoluble in glycerin. 

Perillartine, a-syn-oxime of perillaldehyde, is reported to be 2000 times sweeter than sucrose.48 49 Perillaldehyde is a principal volatile oil of Perilla frutescens (L.) Britton (Labiatae) and is reported to be only slightly sweet. Perillartine is used as a replacement for maple syrup and licorice for the sweetening of tobacco in Japan. However, due to its low solubility in water as well as a menthol-licorice off-taste, there is some limitation to its use. 

Preparative Methods obtained by reaction of (—)-menthol with p-toluenesulfinyl chloride. This esterification showed no particular stereoselectivity, giving an equal amount of the two sulfinate diastereomers. In order to avoid a chromatographic separation, it is possible to epimerize these sulfinate esters in acidic medium and displace the resulting equilibrium towards the less soluble isomer, (—)-menthyl (5)-p-toluenesulfinate, in 80% yield (eq 1). This procedure was later extended to large scale preparation. ... 

Terpenes are reputed to increase cholesterol solubility in bile, though are less effective than bile acids. There are two such preparations available, Rowatinex and Rowachol , containing some combination of the following anethol, borneol, camphene, cineole, mendone, menthol, pipene and renchone, in olive oil. Direct contact dissolution by direct injection of organic solvents, such as methyl tert-butyl ether (MTBE), is sometimes used. 

Properties Colorless liquid menthol-like odor. Bp 227-228C, d 0.922-0.927, optical rotation -72 degrees 47 minutes to -73 degrees 18 minutes, refr index 1.447. Slightly soluble in water miscible with alcohol and ether. Combustible. 

The syntheses of ibuprofen, (S)-metolachlor, and (-)-menthol represent only three of the numerous uses of soluble transition metal complexes to catalyze, often stereoselectively, key steps in the production of biologically important compounds in the laboratory or on an industrial scale. Discussions in Chapter 12, especially with regard to asymmetric conditions, will explore more fully the use of these catalysts in the synthesis of other organic compounds. 

Insoluble in water, soluble in most organic solvents made by esterification of menthol and salicyclic acid. 

Other examples are deoxycorticosterone (3-maltoside " and menthol 3-glucoside. Deoxycorticosterone glycosides show various solubilities depending on the sugar conjugate (Table 38.4). ... 

Menthol (3-glucoside is a water-soluble, non-irritating prodrug of menthol that can be used, like glucovaniUin, the 3-D-glucoside of vanillin, as a pharmaceutic flavor adjuvant. The use of sugar moieties as drug carriers has been reviewed by Chavis and Imbach. ... 

Sovova, Jez J. Solubility of menthol in supercritical carbon dioxide. J Chem Eng Data 1994 39 840. 

Liquid-liquid extraction is generally reserved for more complex samples because it offers poorer precision than other techniques. It is most commonly used for the preparation of biological samples in which less precise methods can be tolerated. Occasionally, however, an extraction is necessary for the determination of a water-insoluble compound in a water-soluble matrix, such as the analysis of fat-soluble vitamins in tablets or menthol in pharmaceutical lozenges. In these cases, the water-soluble matrix must be treated with water to gain access to the analytes, but the solvent cannot be made sufficiently nonpolar to dissolve the analytes by adding a water-miscible solvent. 

The compound to the left below, 2-methyl-2-propanol, often called t-butyl alcohol, is an octane booster for unleaded gasoline. The other compound, menthol, affects the cold receptors on the tongue so as to produce a cool taste when added to foods and medicines. Which of these two compounds would you expect to be more soluble in water ... 

Treatment of racemic methoxysilane 30 with (-)-menthol afforded a mixture of diastereomeric menthoxysilanes 31. Fractional crystallization from pentane gave the less soluble diastereomer ([a]D -53.9°) in 46% yield. Lithium aluminum hydride reduction led to (+)-l-naphthylphenylmethylsilane (4, [a]D +33.4°). The more soluble diastereomer similarly gave rise to (-)-l-NpPhMeSiH ([a]D -32.8°). The absolute configuration of (+)-l-NpPhMeSiH was shown to be R by X-ray diffraction studies (45). 

Menthol—ifrnMyf ofroAof——156—exists in essential oil of peppermint It crystallizes in colorless prisms fumble at 36 (96 .8 F.) sparingly soluble in water readily soluble in alcohol, ether, carbon disul phide, and in acids. CorrespondiDg to it are a series of menihyl ethers. 

CjHjCljOj Noncombustible solid. Reacts with strong bases, amines, amides, inorganic hydroxides alkalis, alkaline earth metals alkali carbonates ammoniacal silver nitrate strong oxidizers soluble barbiturates producing chloroform and formate. Incompatible with camphor, menthol, or thymol. Contact with hydroxylamine produces poisonous hydrogen cyanide gas. Attacks metals in the presence of moisture. In heat of decomposition or fire, releases hydrogen chloride and other toxic fumes. 

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