JP2000302776A - Production of dihydropyran - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dihydropyran compound useful for an industrial raw material for perfume while reducing the quantity of halogen-containing organic compounds as by-products by reacting a specific aldehyde with a specific diene compound in the presence of a halogen-based Lewis acid catalyst and then by heat-treating the reaction product in the presence of an alkali. SOLUTION: By reacting an aldehyde of the formula R1-CHO (wherein R1 is H, a 1-12C alkyl or the like), e.g. benzaldehyde with a diene compound of formula I (wherein R2 and R3 are each H, a 1-6C alkyl or the like), e.g. isoprene in the presence of a halogen-based Lewis acid catalyst (e.g. aluminum chloride) and then by heat-treating the reaction product in the presence of an alkali (e.g. sodium hydroxide), a dihydropyran of formula II (e.g. 6-phenyl-4-methyl-5,6- dihydro-2H-pyran) is obtained. The heat treatment is carried out at 100-250 deg.C for 0.5-20 h. and the added quantity of the alkali is preferably 0.1-10 mol times the halogen content in the reaction product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing high-quality dihydropyran by reducing by-product halogen-containing organic compounds.

[0002]

BACKGROUND OF THE INVENTION Dihydropyran is an important industrial raw material for fragrances. For example, α-
Phenyl-dihydropyran can be converted to 5-phenylpentanol, which is of particular interest as a perfume, by reductive opening of the pyran ring (Switzerland Patent No. 655952). Also,
6-phenyl-4-methyl-5,6-dihydro-2H-
Dihydropyrans such as pyran, 6-phenyl-2,4-dimethyl-5,6-dihydro-2H-pyran and 6-butyl-2,4-dimethyl-5,6-dihydro-2H-pyran are themselves fragrances. (US Patent No. 36
No. 81263, and Arm. Khm. Zh. (1976), 29 (3), 276-2
77

As a method for producing these dihydropyrans, Japanese Patent Publication No. 6-99419 discloses a method in which a Lewis acid is used as a catalyst and a nitro compound is used as a co-catalyst by a heterodiels-Alder reaction between an aldehyde and a diene. However, they were not satisfactory in terms of yield and productivity. The present inventors have solved the drawbacks of the above method and found that dihydropyran can be easily prepared with high productivity and high yield, and have already filed a patent application (Japanese Patent Application Laid-Open No.
-109980, JP-A-10-338687).

However, in these methods, since a halogen-based Lewis acid catalyst such as aluminum chloride is used, the resulting dihydropyran contains a by-product halogen-containing organic compound. Halogen-containing organic compounds may be decomposed by heat or light to generate hydrogen halide gas, which is not preferable from the viewpoint of corrosion of manufacturing equipment and environmental protection. On the other hand, since the by-product halogen-containing organic compound and dihydropyran have close boiling points, separation by precision distillation or the like is very difficult, and it has been difficult to obtain high-quality dihydropyran.

An object of the present invention is to provide a method for producing high-quality dihydropyran in which halogen-containing organic compounds produced as by-products are reduced.

[0006]

The present invention provides a compound represented by the general formula (I): R ¹ -CHO (I) wherein R ¹ is a hydrogen atom or an alkyl or alkenyl group having 1 to 12 carbon atoms or an alkyl group. And an aldehyde represented by a cycloalkyl group having 3 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms which may be substituted by an alkyl group or an alkoxy group. Aldehyde (I)) and the general formula (II):

[0007]

Embedded image

(Wherein R ² and R ³ are the same or different and each represent a hydrogen atom or an alkyl or alkenyl group having 1 to 6 carbon atoms) (hereinafter referred to as diene compound (II)) Is reacted in the presence of a halogen-based Lewis acid catalyst, and then the reaction product is subjected to heat treatment in the presence of an alkali, general formula (III):

[0009]

Embedded image

(Wherein, R ¹ , R ² and R ³ have the above-mentioned meanings).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the aldehyde (I), R ¹ has the same meaning as above, but is preferably an alkyl group having 3 to 12 carbon atoms, or a total of 6 to 6 carbon atoms which may be substituted by an alkyl group.
12 aryl groups, more preferably 6 to 10 carbon atoms in total.
Aryl group, particularly preferably a phenyl group, o-, m
-, P-tolyl group.

Specific examples of aldehyde (I) include benzaldehyde, o-, m-, p-tolualdehyde, naphthaldehyde, butyraldehyde, valeraldehyde, caproaldehyde, heptaldehyde, capryaldehyde, caprinaldehyde, laurinaldehyde and the like. Is mentioned.

In the diene compound (II), R ² and R ³ have the same meaning as described above, but are preferably a hydrogen atom or a methyl group. Specific examples of the diene compound (II) include isoprene, 2-methyl-1,3-pentadiene, butadiene,
1,3-pentadiene and the like; isoprene and 2
-Methyl-1,3-pentadiene is particularly preferred.

The halogen-based Lewis acid catalyst used in the present invention is preferably aluminum chloride, tin tetrachloride, or boron trifluoride. In the present invention, a co-catalyst may be used. As the co-catalyst, nitro compounds described in JP-B-6-99419, bases described in JP-A-10-109980,
Esters, ethers and ketones described in JP-A-10-338687.

The reaction of the present invention can be carried out without a solvent or with a solvent. Solvent used in the present invention,
Hydrocarbon solvents are preferred, including benzene, toluene, xylene, pentane, hexane, cyclohexane, petroleum ether and the like.

In the present invention, the reaction product obtained as described above is heat-treated in the presence of an alkali. By such heat treatment, the by-product halogen-containing organic compound can be decomposed and removed. The method of heat treatment is
100-250 ° C by adding alkali, more preferably 150-250 ° C
0.5 to 20 hours at a temperature of 200 ° C, more preferably 1 to 5 hours
The method of heating and stirring for hours is preferable. Also, after the heat treatment,
It is particularly preferred to carry out further distillation. For the distillation, it is preferable to use a distillation apparatus having 5 to 30 rectification columns.

As the alkali used in the present invention, hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, calcium hydroxide and magnesium hydroxide, and alkaline earth metals such as calcium oxide and magnesium oxide. Alkoxides of alkali metals or alkaline earth metals such as metal oxides, sodium methylate, sodium ethylate, potassium methylate,
Examples thereof include alkali metal weak acid salts such as sodium carbonate, potassium carbonate, and sodium phosphate, and alkali metal or alkaline earth metal hydroxides are preferable. The addition amount of the alkali is 0.01 to 0.01 with respect to the halogen content in the reaction product.
The molar ratio is preferably 100 times, more preferably 0.1 to 10 times.

In the present invention, it is more preferable to coexist with an alcohol during the heat treatment in the presence of an alkali, because the halogen-containing organic compound produced as a by-product can be better decomposed and removed. Examples of the alcohol to be used include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol, and polyhydric alcohols having 2 to 6 carbon atoms are particularly preferable. The amount of the alcohol to be added is preferably 0.01 to 100 mol times, more preferably 0.1 to 10 mol times, relative to the halogen content in the reaction product.

[0019]

EXAMPLES In the examples,% is% by weight unless otherwise specified. The chlorine content was measured by X-ray fluorescence analysis (monochrome excitation energy dispersion type).

Example 1 6-phenyl-4-methyl-5,6 represented by the formula (IV)
Of dihydro-2H-pyran (hereinafter referred to as dihydropyran (IV))

[0021]

Embedded image

5.3 g (40 mmol) of aluminum chloride in a flask
And the atmosphere was replaced with nitrogen. To this, 150 mL of toluene and 4.3 g (40 mmol) of anisole were added at room temperature. This was cooled to 0 ° C., and 42.5 g (400 mmol) of benzaldehyde, 62.7% of isoprene
g (921 mmol) was added dropwise over 2 hours while maintaining the temperature at 0 to 5 ° C. After dropping, add 12.5 g of water to 30
Added below ℃. Separate after stirring for 1 hour, chlorine content 0.72
% Of the upper layer was obtained. To this, 10.0 g (120 mmol) of a 48% aqueous sodium hydroxide solution was added, and distillation was performed with a distillation machine having a 15-stage rectification column. 3 when the internal temperature reaches 180 ° C
After stirring for another hour and continuing the distillation again, the chlorine content was 10pp
58.6 g (84% yield) of m 2 dihydropyran (IV) were obtained.

Example 2 In the same manner as in Example 1, the upper layer contained a chlorine content of 0.67%.
6.8 g were obtained. 13.5 g (241 mmol) of calcium oxide in the upper layer
And 7.4 g (120 mmol) of ethylene glycol, and the mixture was distilled with a distillation machine having a 15-stage rectification column. When the internal temperature reached 180 ° C., the mixture was stirred for 3 hours and the distillation was continued again. As a result, 57.5 g of dihydropyran (IV) having a chlorine content of 7 ppm was obtained.
(Yield 83%) was obtained.

Example 3 In the same manner as in Example 1, the upper layer having a chlorine content of 0.70% was used.
5.9 g were obtained. 13.0 g of sodium methylate (241 mm
ol) and 7.4 g (120 mmol) of ethylene glycol.
Distillation was carried out with a still having a rectifying column. Internal temperature 180
When the temperature reached 0 ° C, the mixture was stirred for 3 hours and the distillation was continued again, and dihydropyran (IV) having a chlorine content of 5 ppm or less was added.
8.1 g (83% yield) was obtained.

Example 4 In the same manner as in Example 1, the upper layer having a chlorine content of 0.70% was prepared.
6.6 g were obtained. 48g of sodium hydroxide aqueous solution 10.0g in upper layer
(120 mmol) and 3.7 g (60 mmol) of ethylene glycol were added, and distillation was performed using a distillation machine having a 15-stage rectification column. When the internal temperature reached 180 ° C., the mixture was stirred for 3 hours, and the distillation was continued again. As a result, dihydropyran (I) having a chlorine content of 5 ppm or less was used.
V) was obtained in an amount of 58.0 g (yield 83%).

Example 5 In the same manner as in Example 1, the upper layer contained 0.67% of chlorine.
7.3 g were obtained. 48g of sodium hydroxide aqueous solution 10.0g in upper layer
(120 mmol) and 1.6 g (11 mmol) of triethylene glycol were added, and distillation was performed using a distillation machine having a 15-stage rectification column. When the internal temperature reached 180 ° C, the mixture was stirred for 3 hours and distillation was continued again.
57.8 g (yield 83%) of (IV) was obtained.

Comparative Example 1 In the same manner as in Example 1, the upper layer contained 0.68% of chlorine.
6.9 g were obtained. 24.0 g of 20% aqueous sodium hydroxide solution in upper layer
(120 mmol), and the mixture was stirred at room temperature for 1 hour and the layers were separated.
Distillation was performed by a distillation apparatus having a rectification column having 5 stages, and 58.5 g (yield 84%) of dihydropyran (IV) was obtained, and the chlorine content was 0.1%. Further, chlorine gas was generated during the distillation, and rust was generated in the packing of the rectification column.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junji Koshino 1334 Minato, Wakayama-shi, Wakayama Prefecture F-term in Kao Corporation Research Institute 4C062 BB24 4H039 CA42 CH40

Claims (4)

[Claims] 1. A compound of the general formula (I): R ¹ -CHO (I) wherein R ¹ is a hydrogen atom or an alkyl or alkenyl group having 1 to 12 carbon atoms or an alkyl group which may be substituted with an alkyl group. And an aldehyde represented by the general formula (II): and a cycloalkyl group having 3 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms which may be substituted with an alkyl group or an alkoxy group. 1) (Wherein R ² and R ³ are the same or different and each represent a hydrogen atom or an alkyl group or an alkenyl group having 1 to 6 carbon atoms) in the presence of a halogen-based Lewis acid catalyst. And then subjecting the reaction product to a heat treatment in the presence of an alkali, general formula (III): (Wherein, R ¹ , R ² and R ³ have the same meanings as described above). 2. The production method according to claim 1, wherein distillation is further performed after heat treatment in the presence of an alkali. 3. A heat treatment at a temperature of 100 to 250 ° C. for 0.5 to
3. The process according to claim 1, wherein the process is carried out for 20 hours. 4. The method according to claim 1, wherein an alcohol is present during the heat treatment.