JPH02164848A - Ester interchange - Google Patents

Abstract

PURPOSE:To readily obtain methacrylic esters by initially blending a mixed alcohol composed of ethyl alcohol and butyl alcohol with methyl methacrylate, subsequently carrying out separation based on the boiling points and independently carrying out ester interchange of the respective separated solutions. CONSTITUTION:A mixed alcohol composed of ethyl alcohol and butyl alcohol is initially blended with methyl methacrylate and the resultant mixture is subjected to rectification under the ordinal or reduced pressure to be separated into a mixture solution of ethanol and methyl methacrylate and the other mixture solution of n-butyl alcohol and methyl methacrylate. The above-mentioned separated solutions are independently subjected to ester interchange in the presence of an ester interchange catalyst and a polymerization inhibitor at 50-100 deg.C for 3-20hrs. under the ordinary or reduced pressure to obtain the objective methacrylates such as ethyl methacrylate or butyl methacrylate useful for pigments, textile treatments, adhesions and molding materials in a form of a monomer or a polymer thereof.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a transesterification process.

More specifically, when a mixed alcohol is transesterified with methyl methacrylate, the two are mixed in advance and then separated into a mixture of ethanol and methyl methacrylate and a mixture of n-butanol and methyl methacrylate. ,
The present invention relates to a transesterification method characterized in that each separated liquid is reacted individually.

Methacrylic acid ester is used as the main component of acrylic resin products.

Plastic products made from polymers of methyl methacrylate, a typical methacrylic acid ester, have excellent weather resistance, are transparent and glossy, and have excellent electrical insulation, chemical resistance, and processability.

Furthermore, ethyl methacrylate, butyl methacrylate, and the like are useful substances that can be used as paints, fiber treatment agents, adhesives, and molding materials either as monomers or as polymers.

[Prior Art] Transesterification methods using various catalysts are known as methods for producing methacrylic acid esters.

The reaction formula for transesterifying a methacrylic acid ester and an alcohol is generally expressed as follows.

In these reactions, usually only a single alcohol is transesterified with a methacrylic ester.

For example, when producing ethyl methacrylate, methyl methacrylate and ethanol are transesterified using phenoxybis(triphenylphosphine) copper (
For example, JP-A-55-7244) is known.

In addition, when producing n-butyl methacrylate, methyl methacrylate and n-butanol are combined with sodium hydroxide, dibutyltin dilaurate, lithium hydroxide, lithium acetylacetonate, molybdenum trioxide, zinc acetylacetonate, zirconium acetyl A method of transesterification using a catalyst such as acetonate, iron acetylacetonate, calcium acetylacetonate, barium acetylacetonate (for example, JP-A-52-111
No. 512, etc.) are known.

Although methacrylic acid esters can be synthesized using a single alcohol, the use of a mixed alcohol as in the method of the present invention is cheaper than when a single alcohol is used. Can be done.

The mixed alcohol referred to in the present invention is a by-product from the 1,3-butanediol manufacturing process, and is composed of ethanol and n-butanol.

This by-product mixed alcohol has few impurities and is of a grade comparable in quality to commercially available ethanol or n-butanol.

Because it is cheaper than commercially available alcohol,
It is usually used to produce esters of organic acids or glycol ethers.

Therefore, if a mixed alcohol is used in the synthesis of methacrylic ester by the transesterification method, methacrylic ester can be produced at low cost.

By the way, when this mixed alcohol is used as it is and transesterified with methyl methacrylate in the presence of a sodium methylate catalyst or the like, ethyl methacrylate and n-butyl methacrylate are produced in high yield.

[Problems to be Solved by the Invention] However, when separating and purifying each component from the above-mentioned reaction bile mixture, ethyl methacrylate can be successfully recovered due to the relationship between the boiling points of each substance, but n-butyl methacrylate is recovered during the reaction. There is a problem in that it is not possible to effectively separate the high-boiling substances produced.

In view of the above situation, the inventor of the present invention has made extensive studies and found that
The present invention has been completed.

[Means for Solving the Problems] That is, the present invention provides a method for transesterifying a mixed alcohol consisting of ethyl alcohol and butyl alcohol with methyl methacrylate.

■After mixing mixed alcohol and methyl methacrylate■(a
) separated into a mixture of ethyl alcohol and methyl methacrylate and (b) a mixture of butyl alcohol and methyl methacrylate.

A transesterification method characterized by reacting the liquid (a) and the liquid (b) separately.

The transesterification method of the present invention will be explained in detail below.

The mixed alcohol used in the present invention is a by-product in the manufacturing process of 1,3-butanediol, and as mentioned above, it can be obtained at a lower cost than commercially available ethanol and n-butanol.

And, regardless of the ratio of ethanol and n-butanol in this mixed alcohol, it can be used in the present invention.

However, the mixed alcohol used in the present invention is 1,3-
It goes without saying that it is not limited to by-products in the butanediol manufacturing process, but may also be derived from other processes or uses.

Further, the methacrylic acid ester used in the present invention is methyl methacrylate.

This is synthesized by the acetone cyanohydrin method or the like.

Mixed alcohol and methyl methacrylate as raw materials can be mixed in any ratio;
It can be separated into a mixture of ethanol and methyl methacrylate and a mixture of n-butanol and methyl methacrylate.

At this time, a mixture of ethanol and methyl methacrylate is distilled out from the top of the column, leaving a mixture of n-butanol and methyl methacrylate in the pot.

The separation operation can be carried out under normal pressure or reduced pressure.

The can temperature at that time is in the range of 50 to 150°C, but in order to prevent polymerization of the methacrylic ester, it is preferable to suppress the can temperature to 100°C or less.

Separation can be carried out by conventional rectification.

At this time, almost no polymerization occurs even if no polymerization inhibitor is used.

The mixture of ethanol and methyl methacrylate and the mixture of n-butanol and methyl methacrylate are then separately transesterified by the method described below.

The reaction is carried out as follows.

In the method of the present invention, catalysts known as catalysts for transesterification reactions, such as sodium methylate, lithium methylate, sodium hydroxide, lithium hydroxide, and tetraalkoxytitanium, can be used.

It can be used in a molar ratio of 300 to 3000 ppm based on the number of moles of methyl methacrylate and ethanol, and methyl methacrylate and n-butanol in the charging solution.

Although the reaction proceeds even at 300 ppm or less, there is a drawback that the reaction rate becomes slow.

Furthermore, if the catalyst is used in an amount of 3000 ppm or more, secondary reactions are likely to occur, resulting in compounds and polymers with a large number of double bonds.

Preferably, the amount of catalyst used is 1200 to 1800 ppm.

In general, catalysts can be added in solid form, but
In order to further increase the activity and reduce the amount used, it is preferable to dissolve it in a solvent and add it.

The catalyst may be charged either intermittently or continuously, but it is preferably charged continuously to minimize side reactions.

The molar ratio of methyl methacrylate and alcohol to be charged is in the range of methyl methacrylate/alcohol=115 to 5, preferably 1/2 to 2.

This is because using too much of one substance slows down the reaction.

The reaction time varies depending on the amount of raw materials used, temperature, amount of catalyst, etc., but is usually 3 to 20 hours.

The reaction can be carried out under normal pressure or reduced pressure.

The can temperature is in the range of 50 to 150°C, but in order to further reduce polymerization of the methacrylic ester, it is preferable to keep it below 100°C.

Moreover, if it is too low, the reaction will be difficult to proceed.

In the present invention, the reaction is preferably carried out by batchwise reactive distillation.

By extracting methanol produced by transesterification from the top of the column azeotropically with methyl methacrylate, the equilibrium in the general reaction formula is significantly shifted and the reaction proceeds.

The reaction is terminated when methanol is no longer generated.

Further, as a polymerization inhibitor, it is preferable to charge a polymerization inhibitor in a weight ratio of 500 to 5000 ppm based on the total raw materials into the reaction vessel before the reaction.

Moreover, even during the reaction, from the top of the fractionation column, 300 to 3500 pp by weight is added to the total amount charged until the end of the reaction.
Add m polymerization inhibitor.

This should be done continuously during the reaction.

Any polymerization inhibitor can be used, such as phenothiazine, hydroquinone monomethyl ether, methylene blue, etc. These can be prepared using an organic solvent such as alcohol, or as a solution of the same methacrylic ester as the desired product.

After the reaction is complete, the ethyl methacrylate and n-butyl methacrylate products can be recovered by purification.

Purification can be carried out under reduced pressure or normal pressure.

The temperature of the reaction vessel during distillation can be 50 to 200°C.

In order to further reduce polymerization, it is preferable to adjust the degree of vacuum so that the temperature of the reaction vessel at the end of distillation is 100° C. or lower.

Also, during distillation, a polymerization inhibitor was added at 50% of the reaction crude liquid.
~8000 ppm is charged from the column.

Any polymerization inhibitor can be used and can be provided in solid or solution form. Preferably, it is prepared as a solution of the same methacrylic ester as the target product.

Hereinafter, the method of the present invention will be specifically explained with reference to Examples.

Example 1 Internal volume 2000 with thermometer, dropping funnel and fractionation column
In a mJl flask, mixed alcohol (552.5 g < ethanol, 467.2 g: 10.14 mol, n-butanol, 85.3 g: 1.15 mol) and methyl methacrylate (699.3 g, 699.3 mol) were added. The mixture was charged and heated at a pressure of 200 mmHg.

467.2 g of ethanol (10
, 14 mol) and methyl methacrylate 513, Og(5,
A mixture of 1.32 g (0.02 mol) of n-butanol and n-butanol was distilled out.

To this mixture was added 164.7 g of methyl methacrylate (1
, 64 mol), phenothiazine 0.579 g (0,0
After adding 03 mol), this liquid was charged into another reactor.

After heating at normal pressure and stabilizing the system, a 28% methanol solution of sodium methylate (4.9%) was added as a catalyst.
g was added intermittently from the dropping funnel over 4 hours.

At the same time, 1.39 g of hydroquinone monomethyl ether was continuously added from the top of the column.

After the reaction started, the generated methanol was distilled out together with methyl methacrylate and ethyl methacrylate.

The reaction temperature was 74 to 88°C for 5 hours and 30 minutes.

After the reaction, 1.90 g of an 85% by weight aqueous phosphorus 'fIi solution was added, and vacuum distillation was carried out at 150 mm Tg for 6 hours to obtain the desired ethyl methacrylate (G, C, purity 99.0%).
281.0 g of the above) was obtained.

During the distillation, 55.6 g of a 10% solution of hydroquinone monomethyl ether in ethyl methacrylate were added. The yield based on methyl methacrylate was 36%.

On the other hand, 186.3 g (<1°86 mol) of methyl methacrylate and n-butanol (84.0 g (1°14 mol)
To the mixture were added 0.74 g (0.10 mol) of n-butanol and 0.14 g (0.0007 mol) of phenothiazine.

After heating at 200 to 400 mmHg and stabilizing the system, 0.90 g of a 28% methanol solution of sodium methylate was added intermittently over 2.5 hours from the dropping funnel, and the resulting methanol was added to methyl methacrylate. It was distilled out azeotropically. The reaction temperature was 55-102°C.
The reaction was carried out for 4.5 hours.

During the reaction, 1 of hydroquinone monomethyl ether
3.5 g of 0% n-butyl methacrylate solution was added to the column.

After the reaction, 0.35 g of 85% by weight aqueous phosphoric acid solution was added, and vacuum distillation was carried out at 100 mmHg for 7° for 3 hours.
n-butyl methacrylate (G, C.

160.5 g of the product (purity of 99.5% or higher) was obtained.

During the distillation, 3.9 g of a 10% n-butyl methacrylate solution of hydroquinone monomethyl ether was added.

The yield based on 11-butanol was 86%.

[Example 2] 466.6 g of mixed alcohol was placed in the same apparatus as in Example 1.
After charging (ethanol: 405.2 g, 879 mol), n-butanol: 61.4 g, 0°83 mol) and methyl methacrylate (318.5 g < 3.18 mol),
200mmHg, 47.5-82°C for 14.5 hours,
405.2 g (<8.79 mol) of ethanol and 271.7 g (2.71 mol) of methyl methacrylate were distilled out. To this mixture was added 314.6 g of methyl methacrylate (3
, 14 mol) under normal pressure in the same manner as in the previous example.
The reaction was carried out for 26.5 hours at a can temperature of 74 to 88°C.

During this time, 4.24 g of a 28% methanol solution of sodium methylate was charged over 3.5 hours, and 16.5 g of a 10% ethyl methacrylate solution of hydroquinone monomethyl ether was charged from the top of the column over 6.5 hours. 85% of phosphoric acid after reaction
After adding 64 g of aqueous solution], 150 mmHg, 7
When distilled under reduced pressure for an hour, the yield of ethyl methacrylate (G, C, purity 99%) was 50% based on methyl methacrylate.
% or more) was obtained.

During this time, 26.5 g of a 10% solution of hydroquinone monomethyl ether in ethyl methacrylate was added. On the other hand, n-
Butanol, 61. ．． After adding 77.6 g (0.78 mol) of methyl methacrylate to a mixture of 4 g (0.83 mol) and 46.8 g (0°47 mol) of methyl methacrylate, the mixture was heated at 200 to 400 mmHg for 6.5 hours. The reaction was carried out at a can temperature of 65 to 125°C.

During this time, a 28% methanol solution of sodium methylate
．． 60 g was added over 2.8 hours, and 1.3 g of a 10% n-butyl methacrylate solution of hydroquinone monomethyl ether was added from the top of the column over 6.5 hours.

After the reaction, 0.23 g of 85% phosphoric acid aqueous solution was added, and 1
When purified at 00 mmHg for 7.5 hours at a can temperature of 92 to 140°C, n-butymethacrylic acid # (G, C, purity 9
9.5% or more) was obtained at 90% (based on n-butanol).

During this time, 3.0 g of a 10% n-butyl methacrylate solution of hydroquinone monomethyl ether was added. [Reference Example] (When mixed alcohol was directly transesterified) To the same apparatus as in Example, 1063 g of methyl methacrylate was added.
0g (10,62 mol), mixed alcohol 701.4
g (ethanol 605.3 g, 13.1 mol), n-
96.1 g (1°30 mol) of butanol and 8.82 g (0,044 mol) of phenothiazine were charged.

Then, while intermittently adding 7.25 g of a 28% methanol solution of sodium methylate over 2.8 hours,
React for 6.5 hours at 0-760 mmHg.

Can temperature was 75-91°C.

Meanwhile, 56.3 g of a 10% solution of hydroquinone monomethyl ether in ethyl methacrylate was added from the top of the column.

After the reaction, 2.76 g of an 85% aqueous solution of phosphoric acid was added, and the temperature of the can was 75-1 for 22.5 hours at 40-150 mmHg.
Distilled at 08°C.

During this time, 55.8 g of a solution of hydroquinone monomethyl ether in ethyl methacrylate was added from the top of the column.

As a result, ethyl methacrylate (G, C, purity 99.0
% or more) was obtained, but methacrylic acid n
Only 232.6 g of -butyl G and C with a purity of 70% were obtained.

Claims (1)

[Claims] When carrying out a transesterification reaction between a mixed alcohol consisting of ethyl alcohol and butyl alcohol and methyl methacrylate, (1) after mixing the mixed alcohol and methyl methacrylate (
2) It is characterized by separating into (a) a mixture of ethyl alcohol and methyl methacrylate and (b) a mixture of butyl alcohol and methyl methacrylate, and reacting the (a) liquid and the (b) liquid separately. transesterification method.