JPH1129517A - Production of acetal compounds - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject compound useful as a raw material for perfumes, agricultural chemicals, medicines, etc. in a good yield even in the presence of water in a reaction system by reacting an aldehyde or ketone with an alcohol in the presence of a specific nickel complex catalyst. SOLUTION: This method for producing an acetal compound of formula III or formula IV comprises reacting an aldehyde or ketone of formula I [R<1> , R<2> are each H, a (substituted) 1-20C monovalent hydrocarbon group, or R<1> , R<2> are bound to each other to form an alkylene group (containing an ether bond)] with an alcohol of the formula: R<3> -OH [R<3> is a (substituted) 1-20C monovalent hydrocarbon group] or the formula: HO-R<4> -OH [R<4> is an alkylene (containing an ether bond)] in the presence of a nickel complex catalyst of formula II [R<5> , R<6> are each a (substituted) saturated hydrocarbon group or a (substituted) aromatic hydrocarbon group] [e.g. bis(2-butene-2,3-dithiolate) nickel].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an acetal. Acetals obtained by the present invention are compounds useful as raw materials for fragrances, agricultural chemicals, medicines and the like.

[0002]

2. Description of the Related Art Hitherto, many methods for synthesizing an acetal from an aldehyde or ketone and an alcohol have been reported, and for example, the following methods are known. Synthesis method using p-toluenesulfonic acid as a catalyst [Org. Synth. Coll. Vol. V, p. 303 (19)
73)). Synthesis using pyridinium p-toluenesulfonate as a catalyst [Synthesis, p. 724 (19)
1979)]. Method for synthesis using an acidic ion exchange resin as a catalyst [J. Chem. Soc. Perkin Trans I, page 158 (1.
979)]. A method of synthesis using aluminum chloride as a catalyst [Synthesis, p. 711 (1989)]. Synthesis method using alumina as a catalyst [Tetrah
edron Lett., 4764 (1985)].

[0003]

However, in the methods for producing acetal described in the above items,
The acidity of the acid used is high.For example, when applied to the synthesis of unstable acetal such as acetal generated from enal or enone, acetal generated from allyl alcohols, as a side reaction, dealcoholization reaction or conversion from raw alcohol The dehydration reaction proceeds, and the desired acetal cannot be obtained in good yield. Further, in the method for producing an acetal described above or above, when an alcohol having a high water content is used, or when dehydration from the reaction system is not sufficiently performed, a catalyst to be used is deactivated and the reaction is stopped. However, there is a problem that the operation does not proceed.

Accordingly, the present invention solves the above-mentioned problems, and is a method for producing acetal which is applicable to the synthesis of unstable acetal and to the case where moisture is present in the reaction system, and which can be widely used. The task is to provide

[0005]

According to the present invention, the above object is achieved by the following formula (1).

[0006]

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(Wherein, R ¹ and R ² each represent a hydrogen atom or a C ¹ -C 1, which may have a substituent (s))
Represents a monovalent hydrocarbon group. R ¹ and R ² may be taken together to represent an alkylene group which may have an ether bond. ) Or an aldehyde or ketone represented by the following formula (2) or the following formula (3): R ³ —OH (2) HO—R ⁴ —OH (3) (wherein, R ³ has a substituent. 1 to 2 carbon atoms
Represents a monovalent hydrocarbon group of 0. R ⁴ represents an alkylene group which may have an ether bond. ) Is reacted with an alcohol represented by the following formula (4) or (5).

[0008]

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[0009]

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(In the formula, R ¹ , R ² , R ³ and R ⁴ are as defined above.) When producing an acetal represented by the formula (6),

[0011]

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(Wherein R ⁵ and R ⁶ represent a saturated hydrocarbon group which may have a substituent or an aromatic hydrocarbon group which may have a substituent) The problem is solved by providing a method for producing an acetal, which is characterized in that it is used.

In the present invention, the starting material ketone,
In the above formulas (1) to (5) representing aldehydes and alcohols and acetals which are target compounds,
Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹ , R ² and R ³ include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t
Alkyl groups such as butyl group, amyl group, isoamyl group and octyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as allyl group, methallyl group, crotyl group and prenyl group; 2-propynyl group and the like Alkynyl group; phenyl group, tolyl group, xylyl group,
An aryl group such as a naphthyl group; an aralkyl group such as a benzyl group and a phenethyl group; a cinnamyl group.

The substituent which these hydrocarbon groups may have may be any as long as they do not adversely affect the acetalization reaction. Examples thereof include halogen atoms such as chlorine, bromine and iodine; carboxyl groups. An alkoxycarbonyl group such as a methoxycarbonyl group and an ethoxycarbonyl group; and an alkoxy group such as a methoxy group and an ethoxy group.

Further, when R ¹ and R ² together represent an alkylene group which may have an ether bond, examples of the alkylene group include an ethylene group, a propylene group, a tetramethylene group and a pentane group. Examples thereof include a methylene group and a divalent group represented by the following formula.

-CH ₂ -O-CH ₂ --CH ₂ -CH ₂ -O-CH ₂ -CH _2-

Specific examples of the alkylene group which may have an ether bond represented by R ⁴ are the same as those described above.

The aldehyde or ketone used in the present invention is not particularly limited, and may have a double bond, triple bond or aromatic ring in the molecule. Here, if specific examples of the aldehyde or ketone are given, examples of the aldehyde include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde,
Isobutyraldehyde, isovaleraldehyde, hexanal, octanal, acrolein, methacrolein, crotonaldehyde, senecioaldehyde, citral, citronellal, benzaldehyde, cinnamaldehyde, etc .; and ketones such as methyl ethyl ketone, pinacolone, cyclohexanone, -Octanone, mesityl oxide, 6-methyl-5-hepten-2-one, acetophenone, propiophenone and the like.

The alcohol used in the present invention includes, for example, methanol, ethanol, propanol, butanol, allyl alcohol, methallyl alcohol, prenol, isoprenol, geraniol,
Nerol, benzyl alcohol, 2-phenylethanol, ethylene glycol, 1,2-propanediol,
Primary alcohols such as 1,4-butanediol and diethylene glycol are preferred from the viewpoint of the reaction rate.

The amount of the alcohol used is not particularly limited. However, in order to obtain the desired acetal in good yield, the hydroxyl group in the alcohol is usually added to 1 mol of the carbonyl group in the aldehyde or ketone. It is used in a proportion of at least 1 mol, preferably at least 2 mol.
There is no particular upper limit on the amount of the alcohol used, but it is preferable that the amount be within a range that is not disadvantageous in view of the production cost of the acetal. Usually, 1 mole of the carbonyl group in the aldehyde or ketone is used in the alcohol. It is used in such a ratio that the number of hydroxyl groups is 10 mol or less.

In the formula (6) representing the nickel complex used in the present invention, the saturated aliphatic hydrocarbon groups represented by R ⁵ and R ⁶ include, for example, methyl group, ethyl group, propyl group, isopropyl group, n- Alkyl groups such as butyl group, isobutyl group and isoamyl group; cyclohexyl group,
A cycloalkyl group such as a cyclooctyl group; and the aromatic hydrocarbon group represented by R ⁵ and R ⁶ includes, for example, an aryl group such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group; a benzyl group And an aralkyl group such as a phenethyl group. Also, R ⁵ and R
^{As a} substituent which ⁶ may have, any substituent may be used as long as it does not adversely affect the acetalization reaction, for example, a halogen atom such as a chlorine atom or a bromine atom; a carboxyl group;
Alkoxycarbonyl groups such as methoxycarbonyl group and ethoxycarbonyl group; and alkoxy groups such as methoxy group and ethoxy group.

Here, if a specific example of the nickel complex is shown,
Bis (2-butene-2,3-dithiolate) nickel,
Bis (2-pentene-2,3-dithiolate) nickel, bis (3-hexene-3,4-dithiolate) nickel, bis (1-cyclohexyl-1-propene-1,
2-dithiolate) nickel, bis (1,2-diphenylethylene-1,2-dithiolate) nickel, bis (1,4-diphenyl-2-butene-2,3-dithiolate) nickel, bis [1,2-bis (4-methoxyphenyl) ethylene-1,2-dithiolate] nickel.

As the nickel complex, a commercially available one may be used, or a nickel complex prepared according to the method described in the literature may be used. The nickel complex may be used in a solid state as it is, or may be used after being dissolved in aldehyde, ketone or alcohol as a raw material or a solvent described later.

As the nickel complex, one kind may be used, or two or more kinds may be used in combination. The amount of the nickel complex used is an amount sufficient for the acetalization reaction to proceed, and is set to an amount that does not impair the stability of the acetal as a product. It is in the range of 0.1 ppm to 5% by weight, and from the viewpoint of the stability of the acetal as a product, the operability of the reaction and the reaction rate, it is 5 to 5000 ppm with respect to the reaction mixture.
Is preferable, and more preferably, the amount is within the range of 10 to 1000 ppm with respect to the reaction mixture.

The nickel complex used as a catalyst in the present invention does not have a very high acidity, and its catalytic activity is not impaired even in the presence of water. For this reason, even when the method of the present invention is applied to the synthesis of unstable acetal such as acetal generated from enal or enone, and acetal generated from allyl alcohol, no side reaction occurs and the yield is reduced. Acetals, which are target compounds, can be obtained efficiently. Further, even if the method of the present invention is applied when water is present in the reaction system,
Acetals, which are the target compounds, are obtained in good yield.

In the reaction according to the present invention, a solvent is not essential, but a solvent can be used as long as the acetalization reaction is not inhibited. Examples of the solvent that can be used at that time include, for example, saturated aliphatic hydrocarbon solvents such as hexane, heptane, octane and cyclohexane; aromatic hydrocarbon solvents such as toluene and benzene; ether solvents such as diethyl ether and diisopropyl ether. Solvents: Halogenated hydrocarbon solvents such as methylene chloride, chloroform, dichloroethane, carbon tetrachloride and the like. The amount of the solvent used is not particularly limited, but is desirably within a range that does not impair the volumetric efficiency of the reaction, and is usually within 3 times the volume of the aldehyde or ketone.

The reaction according to the present invention is preferably carried out in an atmosphere of an inert gas such as nitrogen or argon.

The reaction according to the present invention is carried out at a predetermined reaction temperature in a reaction vessel equipped with a stirrer by mixing an aldehyde or ketone, an alcohol, a nickel complex serving as a catalyst, and, if necessary, a solvent. Alternatively, the reaction may be performed by gradually adding alcohol to a reaction vessel equipped with a stirrer in which an aldehyde or ketone and a catalyst have been charged in advance. In this case, the alcohol may be added as it is, or may be dissolved in a solvent and added in the form of a solution.

In the present invention, since water is by-produced as the reaction proceeds, in order to obtain the desired acetal in good yield, it is necessary to remove the water and suppress the hydrolysis of the acetal. preferable. As a method of removing water,
Known methods such as a method of distilling water out of the reaction system by azeotropic distillation, a method of using a dehydrating agent such as a molecular shoe, anhydrous magnesium sulfate, and anhydrous sodium sulfate can be used.

As a method of distilling water out of the reaction system by azeotropic distillation, a method of distilling water as an azeotropic mixture with aldehyde or ketone as a raw material is simple. In this case, it is desirable to separate water from the distillate using a water separator such as a Dean-Stark trap, and to return the distillate after the water separation to the reaction system again. In addition, water can be distilled out of the reaction system using a solvent that can azeotrope with water, such as toluene.

The reaction according to the present invention is usually carried out under normal pressure or reduced pressure, but is preferably carried out in the range of 15 mmHg to normal pressure, more preferably in the range of 100 mmHg to normal pressure. The reaction temperature is appropriately set according to the reaction pressure, but is usually in the range of −30 ° C. to 200 ° C.
The lower the reaction temperature, the higher the yield of acetal tends to be.

After completion of the reaction, the desired acetal is
For example, by a conventional method such as a method of distilling the reaction mixture,
It can be easily separated and obtained from unreacted aldehyde or ketone and alcohol. Acetals thus obtained can be further increased in purity, if necessary, by distillation, column chromatography and the like.

[0033]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 In a 300 ml three-necked flask equipped with a water separator, 84 g (1 mol) of sensioaldehyde and 172 g of prenol (2 mol)
Mol) and bis (1,2-diphenylethylene-1,
12.8 mg of 2-dithiolate) nickel were charged and reacted at 80 Torr and 90 ° C. in a nitrogen atmosphere for 8 hours while removing generated water outside the reaction system by azeotropic distillation.
The obtained reaction solution was analyzed by gas chromatography under the following conditions according to an internal standard method. As a result, sensioaldehyde diprenyl acetal [R ¹ = 2-methyl-1-propenyl group, R ² = hydrogen atom, R ³ = 3-methyl-2-
Butenyl group] was produced in an amount of 192.5 g (0.80 mol, yield based on senecioaldehyde: 80.2%). After the unreacted sensioaldehyde and prenol were distilled off under reduced pressure from the obtained reaction solution, the obtained residue was distilled under reduced pressure to obtain senesioaldehyde diprenyl acetal (boiling point 142 ° C./15 mm
Hg) was obtained.

Gas Chromatography Analysis Conditions Column: PEG-HT (length: 3 m, manufactured by GL Sciences Corporation) Column temperature: 100 ° C. → 240 ° C. (heating rate: 7 ° C. /
Minutes)

Example 2 86 g (1 mol) of isovaleraldehyde and 172 g of prenol were placed in a 300 ml three-necked flask equipped with a water separator.
(2 mol) and bis (1,2-diphenylethylene-
12.6 mg of (1,2-dithiolate) nickel was charged and reacted at 90 Torr and 90 ° C. for 6 hours while removing generated water outside the reaction system by azeotropic distillation under a nitrogen atmosphere. When the obtained reaction solution was analyzed by gas chromatography in the same manner as in Example 1, isovaleraldehyde diprenyl acetal [R ¹ = isobutyl group, R ² =
Hydrogen atom, R ³ = 3-methyl-2-butenyl group] is 20
It was found that 6.4 g (0.85 mol, yield based on isovaleraldehyde: 85.3%) was produced.

Example 3 86 g (1 mol) of isovaleraldehyde and methallyl alcohol 1 were placed in a 300 ml three-necked flask equipped with a water separator.
44 g (2 mol) and 12 mg of bis (1,2-diphenylethylene-1,2-dithiolate) nickel were charged, and at 110 Torr and 90 ° C. under a nitrogen atmosphere, while water produced was removed from the reaction system by azeotropic distillation. The reaction was performed for 6 hours. When the obtained reaction solution was analyzed by gas chromatography in the same manner as in Example 1, isovaleraldehyde dimethallyl acetal [R ¹ = isobutyl group, R ²
= Hydrogen atom, R ³ = 2-methyl-2-propenyl group] is 169.4g (0.88 mol, yield in isovaleraldehyde criteria: 79.9%) were found to have generated.

Example 4 In Example 1, bis (1,2-diphenylethylene-
Same as Example 1 except that 12.8 mg of bis [1,2-bis (4-methoxyphenyl) ethylene-1,2-dithiolate] nickel was used instead of 12.8 mg of (1,2-dithiolate) nickel. The operation was performed to synthesize a senecioaldehyde diprenyl acetal. The obtained reaction solution was analyzed by gas chromatography in the same manner as in Example 1. As a result, 194.8 g (0.81 mol, yield based on senecioaldehyde: 81.2%) of senecioaldehyde diprenyl acetal was produced. I found out.

Example 5 In Example 3, bis (1,2-diphenylethylene-
Bis (2-butene-2,3-dithiolate) nickel 12m instead of 1,2-dithiolate) nickel 12mg
The same operation as in Example 3 was performed except that g was used,
Synthesis of isovaleraldehyde dimethallyl acetal was performed. The obtained reaction solution was analyzed by gas chromatography in the same manner as in Example 3. As a result, 171.5 g of isovaleraldehyde dimethallyl acetal was obtained (0.81 mol, yield based on isovaleraldehyde: 80.9%). )
It turns out that it is generating.

[0040]

According to the present invention, there is provided a method for producing an acetal which can be applied to the synthesis of an unstable acetal such as an acetal formed from an enal or an enone and an acetal formed from an allyl alcohol. The method for producing an acetal according to the present invention can be applied to a case where moisture is present in a reaction system, and has a wide range of use as a method for producing an acetal and is extremely useful.

Claims (1)

[Claims] 1. The following formula (1): (Wherein, R ¹ and R ² each represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. In addition, R ¹ and R ² become one. May represent an alkylene group which may have an ether bond.)
And an aldehyde or ketone represented by the following formula (2) or the following formula (3): R ³ —OH (2) HO—R ⁴ —OH (3) (wherein R ³ has a substituent. Good carbon number 1-2
Represents a monovalent hydrocarbon group of 0. R ⁴ represents an alkylene group which may have an ether bond. ) To react with an alcohol represented by the following formula (4) or (5): Embedded image (Wherein R ¹ , R ² , R ³ and R ⁴ are the same as defined above) in producing the acetal represented by the formula (6): (Wherein, R ⁵ and R ⁶ represent a saturated hydrocarbon group which may have a substituent or an aromatic hydrocarbon group which may have a substituent). A method for producing a characteristic acetal.