JP2000302727A - Production of carboxylic acid ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing plural carboxylic acid esters in a high selectivity at a high aldehyde conversion rate in a method for reacting the aldehyde with methanol and one or more kinds of alcohols other than the methanol in the liquid phase in the presence of molecular oxygen using a catalyst containing at least palladium and producing a methyl ester of the carboxylic acid and an ester of the carboxylic acid with the alcohols other than the methanol. SOLUTION: This method for producing a carboxylic acid ester is characterized by carrying out a reaction of an aldehyde with methanol in raw material ratios of 1-100 mol of the methanol based on 1 mol of the aldehyde and 0.1-10 mol of the alcohol other than the methanol based on 1 mol of the aldehyde.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for reacting an aldehyde with methanol and one or more alcohols other than methanol in a liquid phase using a catalyst containing at least palladium in the presence of molecular oxygen. It relates to a method for producing esters other than methanol of methyl esters and carboxylic acids.

[0002]

2. Description of the Related Art As a method of producing a carboxylic acid ester in one step by reacting an aldehyde and an alcohol in a liquid phase, a method using a palladium-lead catalyst (Japanese Patent Publication No.
No. 35856, JP-B-4-72578, JP-A-57-57
No. 50545), a method using a palladium-tellurium catalyst (Japanese Patent Application Laid-Open No. 61-244304), and a method using a palladium-thallium-mercury catalyst (Japanese Patent Publication No. Sho 57).
No. 35860), a method using a palladium-alkaline earth metal-zinc-cadmium catalyst (Japanese Patent Publication No. 57-57).
No. 19090), a production method using a palladium-bismuth catalyst (JP-B-61-60820, JP-B-62)
-7902, JP-A-5-148184, JP-A-9-
216850, JP-A-9-221453, JP-A-1
No. 0-158214).

In a method for producing a carboxylic acid ester from an aldehyde using a catalyst containing at least palladium in the presence of molecular oxygen, it is possible to produce a carboxylic acid ester using two or more alcohols. JP-A-10-114708, JP-A-10-2
No. 8,865, and the like.

[0004]

The method for simultaneously producing a plurality of carboxylate esters from a plurality of alcohols eliminates the need to prepare a plurality of plants for each carboxylate variety, and switches the variety in a single plant. It is industrially superior in that it can save time and effort. However,
The literature suggesting that a carboxylic acid ester can be produced using two or more alcohols merely mentions the possibility, but does not mention any specific reaction conditions or the like.

Accordingly, the present invention provides a method for reacting an aldehyde with methanol and one or more alcohols other than methanol in a liquid phase using a catalyst containing at least palladium in the presence of molecular oxygen to form a methyl ester of carboxylic acid and An object of the present invention is to provide a method for producing an ester of an alcohol other than methanol of a carboxylic acid, with a high aldehyde conversion and a high selectivity for a plurality of carboxylic esters.

[0006]

According to the present invention, a aldehyde is reacted in the liquid phase with methanol and at least one alcohol other than methanol using a catalyst containing at least palladium in the presence of molecular oxygen. In a process for producing an ester of an alcohol other than methanol with a methyl ester of an acid and a carboxylic acid, an aldehyde 1
A method for producing a carboxylic acid ester, wherein the reaction is carried out at a raw material ratio of 1 to 100 mol of methanol and 0.1 to 10 mol of alcohol other than methanol with respect to mol.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The catalyst used in the present invention is as follows.
It is necessary to contain at least palladium, and there is no particular limitation on catalyst constituent elements other than palladium. Such catalysts include, for example, the many palladium-based catalysts listed in the prior art literature. In particular, palladium, X and Y (where X is tellurium,
At least one element selected from the group consisting of mercury, thallium, lead and bismuth, Y is magnesium, aluminum, calcium, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium, zirconium, silver, It represents at least one element selected from the group consisting of tin, antimony, barium and cerium. The catalyst comprising ()) can be preferably used in the present invention because of good reaction results.

Usually, the catalyst containing at least palladium is silica, alumina, silica-alumina, silica-
A known carrier such as magnesia, zinc oxide, calcium carbonate, barium carbonate, activated carbon, diatomaceous earth, or zeolite carrying a catalyst constituent element is used, but it is not necessarily required to be a supported catalyst. May be used.

In the case of a supported catalyst, the content of palladium element is 1 to 15% by weight, preferably 3 to 13% by weight.
Since the content of the catalyst constituent elements other than palladium varies depending on the element types and combinations, it cannot be unconditionally determined. However, in the case of the above-mentioned catalyst comprising palladium, X and Y, X is 0.1
To 15% by weight, particularly 0.5 to 12% by weight. Y is preferably from 0 to 7% by weight, particularly from 0 to 7% by weight.
5% by weight is preferred. Here, the content of the element means the weight of the metal element in the supported metal or metal compound with respect to the total weight of the catalyst including the support.

The raw materials of the constituent elements of the catalyst used in the production of the catalyst are not particularly limited. Examples of the raw materials of palladium include palladium acetate, palladium chloride, palladium nitrate, palladium sulfate, palladium ammonium chloride and palladium ammine complex salt. And the like. Also,
Examples of the raw material of the catalyst constituent element other than palladium include common metal compounds such as acetate, carbonate, nitrate, sulfate, oxalate, chloride, and hydroxide of the metal.

In the present invention, the aldehyde used as a raw material is not particularly limited. Group aldehydes, of which methacrolein and acrolein are preferred. The aldehyde used as a raw material is preferably one kind, but two or more kinds of aldehydes may be used as a mixture.

The alcohol other than methanol used as a raw material is not particularly limited, and includes, for example, various alcohols such as ethanol and allyl alcohol. Alcohols having a boiling point of 100 ° C. or higher are preferable, and isobutanol, Cyclohexanol, 2-ethylhexanol and tetrahydrofurfuryl alcohol are preferred.

In the present invention, the amount of methanol used in the reaction for producing the carboxylic acid ester is 1 to 100 mol, preferably 2 to 1 mol per mol of the aldehyde.
７０70 mol. The amount of the alcohol other than methanol is 0.1 to 10 mol, preferably 0.5 to 5, and more preferably 1 to 3 per mol of the aldehyde. By setting the amount of methanol and the alcohol other than methanol to such a specific amount, a plurality of carboxylic esters can be produced in high yield.

In the present invention, the reaction for producing the carboxylic acid ester is carried out in a liquid phase, and the catalyst containing at least palladium is used in a suspended or fixed state. The reaction system is not particularly limited, and may be any of a batch system, a semi-batch system, and a continuous system. The type of the reactor is not particularly limited, and for example, an arbitrary type such as a stirred tank reactor, a bubble column reactor, a draft tube type reactor and the like can be applied. The amount of the catalyst used in the reaction varies depending on the type of reaction and reaction conditions to be employed, and cannot be specified unconditionally, and is determined in consideration of a desired conversion rate and the like.

The molecular oxygen source required for the reaction includes air, oxygen-enriched air, oxygen, air diluted with a gas inert to the reaction, and the like. A method for supplying molecular oxygen is not particularly limited, but usually, a gas of a molecular oxygen source is supplied by bubbling into a reaction solution. The supply amount of molecular oxygen per hour is 0.05 to 2 molecular oxygen per mole of aldehyde.
Mole, preferably 0.1-0.5 mole. During the reaction, an oxidizing agent such as hydrogen peroxide may be added to the reaction solution.

It is not always necessary to use a solvent for the reaction, but if it is used, a substance having no functional group which affects the reaction is used. Examples of such a solvent include hydrocarbons such as pentane and hexane, and aromatic hydrocarbons such as benzene and toluene.

The reaction temperature is usually 0-200 ° C, preferably 50-150 ° C. The reaction pressure may be any of normal pressure, pressurization and reduced pressure, but is preferably from normal pressure to
0.4 MPa. The pH of the reaction solution is usually 5 to 8. When the pH of the reaction solution needs to be adjusted, it can be adjusted by adding an alkali metal salt, an alkaline earth metal salt, or the like.

[0018]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The analysis of the reaction product was performed by gas chromatography. The conversion rate of the aldehyde and the selectivity of the carboxylic acid ester were calculated by the following equations. Conversion of aldehyde (%) = A / B × 100 Selectivity of carboxylic acid ester (%) = C / A × 100 where A is the number of moles of aldehyde reacted, and B is the number of moles of aldehyde used for reaction. , C is the number of moles of the carboxylic acid ester formed.

EXAMPLE 1 2.0 g of a catalyst having 5% by weight of palladium-3% by weight of bismuth supported on a silica carrier and methacrolein 3.5 in a 200 ml flask equipped with a reflux condenser.
g (0.05 mol), methanol 80 g (2.5 mol,
50 mol per 1 mol of methacrolein) and 7.4 g of isobutanol (0.1 mol, 2 mol per 1 mol of methacrolein) were added, and air was supplied to the reaction solution at 100 m / min.
The reaction was carried out at a reaction temperature of 70 ° C. for 4 hours while blowing at a rate of 1. As a result of collecting and analyzing the reaction product, the conversion of methacrolein was 81.5%, the selectivity of methyl methacrylate was 90.0%, and the selectivity of isobutyl methacrylate was 4.5%.
Met.

Example 2 7.4 g of isobutanol was added to 2
Example 1 was repeated except that the amount was changed to 13.0 g (0.1 mol, 2 mol per 1 mol of methacrolein). As a result, the conversion of methacrolein was 8
The selectivity was 2.6%, the selectivity for methyl methacrylate was 89.3%, and the selectivity for 2-ethylhexyl methacrylate was 4.1%.

Example 3 As a result of carrying out in the same manner as in Example 1 except that 7.4 g of isobutanol was changed to 10.0 g of cyclohexanol (0.1 mol, 2 mol per 1 mol of methacrolein). Conversion of methacrolein 81.8
%, The selectivity of methyl methacrylate was 90.5%, and the selectivity of cyclohexyl methacrylate was 3.9%.

Example 4 The procedure of Example 1 was repeated except that 7.4 g of isobutanol was changed to 10.2 g of tetrahydrofurfuryl alcohol (0.1 mol, 2 mol per 1 mol of methacrolein). As a result, the conversion of methacrolein was 82.0% and the selectivity of methyl methacrylate was 89.89%.
The selectivity for tetrahydrofurfuryl methacrylate was 9% and 3.8%.

Example 5 3.5 g of methacrolein
(0.05 mol) was changed to 2.8 g (0.05 mol) of acrolein. As a result, the conversion of acrolein was 87.4% and the selectivity of methyl acrylate was 93.4. %, Selectivity of isobutyl acrylate 5.1
%Met.

Example 6 As an alcohol other than methanol, 7.4 g of isobutanol (0.1 mol, 2 mol per mol of methacrolein) was added to 13.0 g of 2-ethylhexanol (0.1 mol). , Methacrolein 1
(2 mol per mol), and the same procedure as in Example 1 was carried out. As a result, the conversion of methacrolein was 83.2%, the selectivity of methyl methacrylate was 89.1%, and the selectivity of isobutyl methacrylate was 4 0.3% and a selectivity of 2-ethylhexyl methacrylate of 3.6%.

Comparative Example 1 The amount of methanol used was 80 g
(2.5 mol, 50 mol per 1 mol of methacrolein) was changed to 32 g (1 mol, 20 mol per 1 mol of methacrolein), and the amount of isobutanol used was 7.4.
g (0.1 mol, 2 mol per 1 mol of methacrolein) was changed to 74.1 g (1 mol, 20 mol per 1 mol of methacrolein). The conversion of methacrolein was 28.3%, the selectivity of methyl methacrylate was 50.6%, and the selectivity of isobutyl methacrylate was 7.8%. When 20 mol of isobutanol was used per 1 mol of methacrolein, conversion and selectivity were low.

[Comparative Example 2] The same procedure as in Comparative Example 1 was carried out except that 74.1 g of isobutanol was changed to 130.2 g of 2-ethylhexanol (1 mol, 20 mol per 1 mol of methacrolein). Conversion of methacrolein 2
The selectivity was 0.4%, the selectivity for methyl methacrylate was 41.6%, and the selectivity for 2-ethylhexyl methacrylate was 8.5%. When 20 mol of 2-ethylhexanol was used per 1 mol of methacrolein, conversion and selectivity were low.

Comparative Example 3 Comparative Example 1 was conducted except that 74.1 g of isobutanol was changed to 100.2 g of cyclohexanol (1 mol, 20 mol per 1 mol of methacrolein).
As a result, the conversion of methacrolein was 14.
The selectivity was 30.5%, the selectivity for methyl methacrylate was 60.5%, and the selectivity for cyclohexyl methacrylate was 9.3%. When cyclohexanol was used in an amount of 20 mol per 1 mol of methacrolein, conversion and selectivity were low.

[Comparative Example 4] The same procedure as in Comparative Example 1 was carried out except that 74.1 g of isobutanol was changed to 102.1 g of tetrahydrofurfuryl alcohol (1 mol, 20 mol per 1 mol of methacrolein). Conversion of methacrolein 20.4%, selectivity of methyl methacrylate 4
6.7% and a selectivity of tetrahydrofurfuryl methacrylate of 4.2%. When 20 moles of tetrahydrofurfuryl alcohol was used per 1 mole of methacrolein, conversion and selectivity were low.

[Comparative Example 5] The same procedures as in Example 1 were carried out except that 7.4 g of isobutanol was not used. As a result, the conversion of methacrolein was 80.2% and the selectivity of methyl methacrylate was 91.4%. Met.

[0030]

According to the present invention, an aldehyde is reacted with methanol and at least one alcohol other than methanol in a liquid phase using a catalyst containing at least palladium in the presence of molecular oxygen to form a carboxylic acid. In a method for producing an ester of an alcohol other than methanol of a methyl ester and a carboxylic acid, a plurality of carboxylic esters can be produced with a high aldehyde conversion and a high selectivity.

Claims (1)

[Claims] 1. The method of claim 1 wherein the aldehyde is converted to a aldehyde in the presence of molecular oxygen.
A method for producing a methyl ester of carboxylic acid and an ester of alcohol other than methanol of carboxylic acid by reacting in the liquid phase with methanol and one or more alcohols other than methanol using a catalyst containing at least palladium. On the other hand, methanol 1
100 mol, alcohol other than methanol 0.1 to 10
A method for producing a carboxylic acid ester, wherein the reaction is carried out at a molar raw material ratio.