Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-04-04
2003-02-04
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C560S231000, C560S236000, C568S670000
Reexamination Certificate
active
06515188
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method for producing 3-l-menthoxypropane-1,2-diol useful as, e.g., a cool-feeling agent or refreshment improving agent, and 1-acyloxy-2-substituted-3-l-menthoxypropanes useful as intermediates in producing the 3-t-menthoxypropane-1,2-diol and a production method thereof. According to the invention, 3-l-menthoxypropane-1,2-diol having high purity and 1-acyloxy-2-substituted-3-l-menthoxypropanes useful as synthetic intermediates of the 3-l-menthoxypropane-1,2-diol can be obtained by simple operation safely and with high yield.
In addition, according to the invention, (2S)-3-l-menthoxypropane-1,2-diol in which configuration of the 2-position of the propane moiety is controlled and which has more excellent refreshing feeling can be obtained with high optical purity.
BACKGROUND OF THE INVENTION
3-l-Menthoxypropane-1,2-diol is a known compound as is described in, e.g., JP-B-61-48813. 3-l-Menthoxypropane-1,2-diol is excellent in safety and has a property to provide l-menthol-like cool-feeling action on the skin and mucous membrane, while it is odorless and has no odor by itself unlike the case of l-menthol. Thus, when 3-l-menthoxypropane-1,2-diol is used, it does not exert influence on the aroma added to the product and can add cool-feeling action to the product. Accordingly, making use of these characteristics of 3-l-menthoxypropane-1,2-diol, it has been proposed to add 3-l-menthoxypropane-1,2-diol to oral compositions such as tooth powder and chewing gum and refreshments such as sherbet and hard candy, and also to aromatic cosmetics such as toilet articles (JP-A-60-25908, JP-A-63-208505), eye packs (JP-A-62-96403) and hair cosmetics (JP-A-62-192312), as well as aerosol compositions for anti-inflammatory drug and analgesic use (JP-A-63-264522).
Conventionally known methods for producing 3-l-menthoxypropane-1,2-diol include (i) a method in which l-menthol is made into sodium salt with metallic sodium or sodium hydride and then reacted with an allyl halide to produce 3-l-menthoxypropane-1-ene which is subsequently converted into an oxide by oxidizing it using an organic peroxide and then hydrolyzed (JP-B-61-48813); and (ii) a method in which l-menthol is added to benzyl glycidyl ether in the presence of a Lewis acid to produce 1-benzyloxy-3-l-menthoxypropan-2-ol which is then subjected to hydrogenolysis in the presence of a palladium-carbon catalyst to eliminate benzyl group (JP-A-7-82200).
However, in the conventional method (i), sodium salt of l-menthol is prepared using metallic sodium or sodium hydride, it has a problem of causing a danger of explosion and generation of hydrogen gas. What is more, since oxidation of 3-l-menthoxypropane-1-ene as the intermediate is carried out using an organic peroxide, it has a danger of causing explosion also from this point, so that this cannot be said as an industrially advantageous method, and there is room for further improvement from the economic point of view.
Also, since the conventional method (ii) is a production method aimed at synthesizing optically active substances, it is necessary to use expensive benzyl glycidyl ether. What is more, since the finally obtained 3-l-menthoxypropane-1,2-diol is contaminated with about 10% of 2-l-menthoxypropane-1,3-diol, it is necessary to carry out purification and fractionation by, e.g., a silica gel column chromatography so that it is difficult to obtain a large amount of 3-l-menthoxypropane-1,2-diol having high purity.
Also, in addition to these conventional methods, (iii) it has been proposed a method in which 1,2-epoxy-3-l-menthoxypropane as a synthetic intermediate of 3-l-menthoxypropane-1,2-diol is synthesized by allowing l-menthol to undergo addition reaction with a 1,2-epoxy-3-halogenopropane such as epichlorohydrin in an aqueous solution in the presence of a base and a quaternary ammonium salt [French Patent 2,479,822 (1981)]. However, it is known that a 1,2-epoxy-3-halogenopropane such as epichlorohydrin is unstable and apt to be decomposed in the presence of an acid or base [“Dictionary of Chemistry” p. 292, published by Tokyo Kagaku Dojin (1989)]. Thus, in the case of this method in which a 1,2-epoxy-3-halogenopropane is allowed to undergo the reaction in the presence of a base, the 1,2-epoxy-3-halogenopropane is decomposed when the reaction is carried out for a prolonged period of time, so that it is difficult to synthesize 1,2-epoxy-3-l-menthoxypropane in a large amount and this cannot be said as an industrially and economically advantageous method.
In addition, (iv) a method in which 1-allyloxy-3-chloro-2-propanol as an optically active glycerol derivative is produced by allowing epichlorohydrin and allyl alcohol to undergo the reaction in the presence of an acidic catalyst has been proposed as the reaction of epichlorohydrin with an alcohol (JP-A-2-221). However, this conventional method (iv) uses only primary allyl alcohol as the alcohol to be used in the reaction, and it does not report on the application to secondary alcohols, much less on the addition reaction with menthol.
Also, as another conventional method, it has been proposed (v) a method in which epichlorohydrin and alcohols are allowed to undergo the reaction in the presence of an acid catalyst and then subjected to an alkali treatment to effect ring closure, thereby converting into a glycidyl ether which is subsequently hydrolyzed, and then a glycerol ether is produced by heating the reaction mixture at a temperature of from 100 to 230° C. in the presence of a salt formed from a strongly basic compound and a weakly acidic compound (JP-A-2000-212114). However, in the case of this method, it is necessary to heat the reaction mixture at a high temperature of from 100 to 230° C., particularly from 150 to 200° C., in the presence of a salt formed from a strongly basic compound and a weakly acidic compound, in order to decompose the organic halogen contained in the hydrolysate of the glycidyl ether, so that this is not an efficient method. What is more, the alcohols used in this method are primary alcohols represented by a general formula: R-(OA)p-OH (wherein R represents a saturated or unsaturated, straight- or branched-chain hydrocarbon radical having from 1 to 36 carbon atoms, A represents an alkylene group having from 2 to 4 carbon atoms, and p is a number of from 0 to 100), and there is no disclosure on the use of secondary alcohols, much less on the use of menthol.
SUMMARY OF THE INVENTION
An object of the invention is to provide a method by which 3-l-menthoxypropane-1,2-diol having high purity can be produced by a simple process, safely and with a high yield.
Another object of the invention is to provide a synthetic intermediate useful in obtaining high purity 3-l-menthoxypropane-1,2-diol.
Still another object of the invention is to provide an efficient method for producing an intermediate useful in obtaining 3-l-menthoxypropane-1,2-diol.
A further object of the invention is to provide a method by which (2S)-3-l-menthoxypropane-1,2-diol whose configuration of the 2-position of the propane moiety is controlled and which has more excellent refreshing feeling can be produced with a high optical purity.
In order to achieve these objects, the present inventors have conducted extensive studies. As a result, they succeeded in producing a 1-acyloxy-2-substituted-3-l-menthoxypropanes as novel compounds, by producing a 1-halogeno-3-l-menthoxypropan-2-ol through the addition reaction of l-menthol with a 1,2-epoxy-3-halogenopropane in an organic solvent in the presence of a Lewis acid, and allowing the thus obtained 1-halogeno-3-l-menthoxypropan-2-ol to react with an aliphatic carboxylic acid alkali metal salt. After further studies, it was found that these novel 1-acyloxy-2-substituted-3-l-menthoxypropanes are chemically stable and can be preserved by themselves, and that the 3-l-menthoxypropane-1,2-diol of interest can be obtained conveniently with a high yield and a high purity by hydrolyzing these 1-acyloxy-2-substituted-3-l-menthoxypropanes.
Thereafter, the
Akiyama Teruyoshi
Amano Akira
Hagiwara Toshimitsu
Miura Takashi
Shippen Michael L.
Takasago International Corporation
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