JPH066557B2 - Amino acid esterification reactor - Google Patents

Description

The present invention relates to an amino acid esterification reaction device, and more specifically, to a circulating amino acid ester compound ester utilizing a pervaporation device using a water-selective permeable membrane. The present invention relates to a chemical reaction device.

[Conventional technology]

In the amino acid esterification reaction, an amino acid ester compound is prepared by reacting an amino acid with an excess of an acid catalyst such as alcohol, hydrochloric acid or sulfuric acid in a reaction vessel.

As the reaction product water is generated as seen in the reaction formula, in order to remove this, a distillation column and a separation column are installed in the subsequent stage of the reaction tank, and the reaction product water and the amino acid ester compound, excess alcohol, acid are installed in the distillation column. The catalyst and dehydrated solvent such as benzene are fractionally distilled. Further, dehydration solvents such as alcohol and benzene are separated in the separation tank.

[Problems to be solved by the invention]

In the conventional apparatus, a distillation apparatus is used to dehydrate the reaction product water, but dehydration by the distillation apparatus has the following problems.

(1) In addition to the separation of the amino acid ester compound and the reaction product water by a distillation apparatus, it is necessary to install a distillation column and a separation column for fractional distillation of the reaction product water, excess alcohol, and dehydrating solvent such as benzene. Excessive equipment load and complicated operation and control are required.

(2) When dehydrating the reaction product water, extra equipment such as a separator for excess alcohol added to increase the esterification rate and a separator for dehydrating solvent such as benzene added to increase the dehydration rate is required. become.

(3) 1m of amino acid in the amino acid esterification reaction
The amount of alcohol is 100 mol or more with respect to ol, and an excessive amount of chemicals such as 10 mol of acid catalyst is required. In particular, the excessive amount of acid catalyst causes corrosion of the reaction system. Even when excess alcohol is returned to the reaction tank, the rate of amino acid esterification is not increased, and it is difficult to separate it from the dehydrated solvent after distillation.

(4) Since a dehydrating solvent such as benzene is easily mixed in the amino acid ester compound during the esterification reaction, it is difficult to use in the fields of medicine and food.

FIG. 2 shows an example of a conventional amino acid esterification apparatus.

When the reaction has proceeded sufficiently by mixing the amino acid with excess alcohol and hydrochloric acid or sulfuric acid as an acid catalyst in the reaction vessel 1 as a reaction tank, the reaction liquid is passed through the pipe 4 to the distillation column 2 to remove the water produced by the reaction. The fed ester compound, water and alcohol are fractionated. At this time, a solvent such as benzene may be added as a dehydrating solvent to the reaction solution to further enhance the dehydrating effect.

In order to dehydrate and dealcoholize the reaction product, the reaction solution is often circulated through a pipe 5 provided between the reaction kettle 1 and the distillation column 2 to perform an operation for increasing the separation rate.

In the distillation column 2, most of the reaction-produced water is fractionally distilled as water vapor from alcohol and a dehydrating solvent, and recovered as an aqueous solution from the pipe 8.

The mixed solution of alcohol and dehydrated solvent passes through the pipe 7 and the heater 6
Is heated to the separation column 3 and the fractionation temperature is strictly controlled to fractionate the alcohol and the dehydrated solvent, and at the same time, residual reaction product water is separated. The alcohol and dehydrated solvent recovered from the tubes 9 and 10 are reused for the next amino acid esterification reaction in the reaction vessel 1.

[Means for solving problems]

The present invention solves the above-mentioned problems of the conventional amino acid esterification reaction device. In the supply chamber of the pervaporation device provided with a water-selective permeable membrane, the presence of the alcohol and the acid catalyst for the amino acid is present in the reaction tank. The amino acid ester compound-containing liquid that underwent the esterification reaction is allowed to flow in, and the reaction product water in the amino acid ester compound-containing liquid is selectively permeated through the water-selective permeable membrane into the permeation chamber of the depressurized pervaporation device. The amino acid ester compound-containing liquid, which has been dehydrated by dehydration and further removed of the reaction product water, is circulated in the reaction tank for carrying out the above-mentioned amino acid esterification reaction, and then re-introduced into the supply chamber of the pervaporation device. .

That is, the present invention separates the reaction product water from the amino acid esterification reaction and the amino acid ester compound-containing liquid,
The main purpose is to reduce equipment cost and operation cost by using without using a distillation column or a separation column that consumes a large amount of energy and without using a dehydrating solvent that is troublesome for separation.

Further, the present invention provides an alcohol required for the esterification reaction,
The purpose of the present invention is to prevent the corrosion of the reaction system due to excess acid by avoiding the use of excess alcohol by making the reaction amount ratio of the acid catalyst with the amino acid as close as possible to an equimolar ratio.

Furthermore, if the present invention can achieve a higher degree of esterification,
The goal is 100%.

The pervaporation method divides the inside of the apparatus into two chambers by a water-selective permeable membrane, that is, a membrane that allows water to pass as water vapor but does not pass a liquid, and one chamber is used as a supply chamber for the liquid to be treated, and the other is used. This is a separation method that utilizes a phase change in which the chamber is the permeation chamber, the supply chamber is a liquid across the membrane, and the permeation chamber is a gas such as vapor. By decompressing the supply chamber and extracting the gas to the permeation chamber, It is applied to the separation of water in the liquid to be treated.

The driving force of permeation in pervaporation is due to the concentration difference between the feed chamber and the permeate chamber in the membrane of the permeate, and the dissolution of components on the membrane surface of the feed chamber into the membrane, diffusion in the membrane, and It is said that the separation (steam) is the mechanism of permeation.

Materials for the water-selective permeable membrane include acetic acid cellulose membrane, acetic acid cellulose derivative membrane, tetrafluoroethylenepolyvinylpyrrolidone membrane, tetrafluoroethylenepolyvinyl graft polymer membrane, polyvinylalcohol membrane, cuprophane membrane, sulfone. Ethylene-ethyl acrylate film,
Ion exchange membranes made of styrene-based, silicon-based, ethylene-based materials, and composite membranes of these materials can be used. In particular, it is most desirable to use a cationic ion exchange membrane as the water selective permeable membrane.

Further, as the water-selective permeable membrane, it is possible to use one that allows water vapor to pass but does not allow liquid to pass, that is, one that has a pore size (surface layer) of 10 to 1,000 Å and a film thickness of 100 to 100,000 Å. Desirably, the shape of the permeable membrane is usually spiral, hollow fiber, cylindrical, flat, etc., but in order to increase the membrane area, use spiral or hollow type. Is desirable.

As the amino acid, a general commercial product (solid matter) may be used, as the alcohol, a monohydric alcohol such as methyl, ethyl, propyl, butyl or isopropyl may be used, and as the acid catalyst, hydrochloric acid, sulfuric acid, etc. Acid catalysts with acid carriers such as the mineral acids or cation exchange resins described above may be used.

The molar ratio of amino acid: alcohol: acid catalyst in the esterification reaction (amino acid ester compound-containing liquid) of the amino acid of the present invention is preferably in the range of 1: 1 to 100: 1 to 2, and particularly 1: 1. A range of up to 10: 1 is most desirable.

The amino acid ester compound of the present invention is preferably produced in an equimolar amount to the amount of amino acid, and the esterification conversion rate is preferably 90% or more.

The temperature for pervaporation of the present invention is preferably in the range of 0 to 150 ° C, and particularly in the range of 50 to 100 ° C, the reaction time is short and the efficiency is good.

It is desirable to reduce the degree of pressure reduction as much as possible, such as 1 to 760 mmHg, in the permeation chamber of the pervaporation apparatus, and to increase the degree of pressure reduction when performing pervaporation at low temperatures. In the case of pervaporation by, it is advisable to use a low degree of pressure reduction.

The flow rate of the amino acid ester compound-containing liquid on the surface of the water-selective permeable membrane is 1 to 1 of the water vapor transmission rate (0.1 to 10 / hr · m ² ).
It is preferably 0 times, and the number of circulation of the amino acid ester compound-containing liquid to the pervaporation apparatus is preferably 2 times or more, particularly preferably 8 to 10 times.

An embodiment of the present invention will be described below. In FIG. 1, reference numeral 11 indicates a water-selective permeable membrane 12 for supply chamber 13 and permeation chamber 14.
The pervaporation apparatus is divided into two chambers, the supply chamber 13 is connected to the reaction vessel 1 as a reaction tank by a pipe 4, and the permeation chamber 14 is connected to a cooling trap 16 provided with a decompression pump 15 by a pipe 7.
The permeate side 14 is communicated with each other to reduce the pressure on the permeate side 14.

Next, the operation of the present invention will be described. The amino acid ester compound-containing liquid obtained by esterifying the amino acid in the reaction kettle 1 in the presence of an alcohol and an acid (hydrochloric acid or sulfuric acid) catalyst is heated to 40 ° C. or higher and the tube 4 When it is allowed to flow into the supply chamber 13 of the pervaporation apparatus 11 via the water, the reaction product water in the amino acid ester compound-containing liquid generated in the reaction step of the amino acid esterification reaction becomes steam in the permeation chamber 14 in a reduced pressure state. The water-selective permeable membrane 12 is vaporized and permeated to be removed. On the other hand, the amino acid ester compound-containing liquid from which the reaction product water has been removed is allowed to flow into the pipe 17 while promoting the amino acid esterification reaction in the supply chamber 13 of the pervaporation apparatus 11. In order to increase the amino acid esterification rate of the amino acid ester compound-containing liquid (mixed liquid of amino acid ester compound, unreacted amino acid, alcohol, and acid catalyst) from which this reaction product water has been removed, the liquid containing the same is subjected to the aforementioned amino acid esterification reaction. The amino acid esterification reaction is further promoted in the reaction kettle 1 after being circulated in the reaction kettle 1 through the pipe 17, and the amino acid esterification reaction is further fed into the supply chamber 13 of the pervaporation apparatus 11 to dehydrate the reaction product water. .

In the present invention, the dehydration rate of the reaction product water from the amino acid ester compound-containing solution is obtained by performing the circulating amino acid esterification reaction in the permeation vaporizer provided with the reaction tank (reaction kettle 1) and the water selective permeable membrane as described above. Also, the amino acid esterification conversion rate can be increased to the maximum as shown in FIGS. 3 and 4 described later.

In addition, the present invention does not need to use a distillation column or a separation column that requires a large amount of energy for fractionating the reaction product water and the alcohol, the acid catalyst, and the dehydrating solvent, unlike the conventional apparatus. The equipment cost and operating cost of the device can be significantly reduced.

Further, in the present invention, an alcohol, an acid catalyst, and a dehydrating solvent are not used in an excessive amount with respect to an amino acid unlike the amino acid esterification reaction by a conventional apparatus, so that various harmful effects caused by this do not occur. .

That is, a pervaporation device provided with a water-selective permeable membrane selectively removes reaction product water unnecessary for the amino acid esterification reaction, and hardly removes alcohol, acid catalyst, etc. required for this reaction. It can be effectively used in equimolar amounts with amino acids in the circulation system amino acid esterification reaction. Therefore, in the present invention, as a matter of course, it is not necessary to separate the alcohol, the acid catalyst and the like from the amino acid ester compound, and the corrosion of the device, the piping and the equipment by the acid catalyst does not occur.

In the present invention, since a dehydrating solvent such as ethanol, which has been conventionally used to enhance dehydration property, is not used, the dehydrating solvent is not mixed in the produced amino acid ester compound. The amino acid ester compound can be used for food additives, medicines and the like.

Examples of the present invention will be described below.

Example 1 A reaction vessel and a pervaporation apparatus as shown in FIG. 1 were used, and the permeation chamber of the pervaporation apparatus was set to a reduced pressure of 4 mmHg.

Then, a solution of 1 mol of glycine, 50 mol of ethyl alcohol, and 1 mol of hydrochloric acid was placed in a reaction vessel at a temperature of 75 ° C to perform an esterification reaction of glycine, and then as a water-selective permeable membrane,
A Nafion membrane having an effective area of 0.8 m ² was introduced into a supply chamber of a pervaporation apparatus, and the reaction product water in the solution was used as water vapor to pervaporate the Nafion membrane to dehydrate the permeation chamber.

The dehydrated reaction solution is circulated again in the reaction kettle and then allowed to flow into the supply chamber of the pervaporation apparatus to repeat the above-mentioned reaction and dehydration treatment, and after such circulation treatment is continued for 8 hours (circulation The esterification conversion rate of glycine was measured 5 times, and the result was as shown by the curve (a) in the graph of FIG. For comparison, the esterification conversion rate of glycine under the same conditions was measured by an amino acid esterification apparatus as shown in FIG. 2 without using the pervaporation apparatus for the water-selective permeable membrane of the present invention. Curve of diagram graph
The result is shown in (b).

When the esterification reaction apparatus of the present invention is installed, the esterification conversion rate of glycine is 98% in 8 hours, but when the apparatus of the present invention is not installed, the same conversion rate is 60% in 8 hours, and , Further improvement of the esterification conversion could not be expected.

Example 2 The esterification conversion rate of glycine was measured by the same method as in Example 1 except that the amount of hydrochloric acid as an acid catalyst for glycine and alcohol was changed using the same apparatus as in Example 1.

The curve (a) in the graph of FIG. 4 shows the esterification conversion rate of glycine when the esterification reaction was carried out for 8 hours with the molar ratio of glycine and hydrochloric acid being 1: 1. The esterification rate in this case Has reached 98%.

The curve (b) in the graph of FIG. 4 shows the esterification conversion rate of glycine when the esterification reaction was carried out for 8 hours with the molar ratio of glycine and hydrochloric acid being intentionally set to 1: 4 as a comparative example. The esterification rate after 8 hours was substantially the same as that in the case where the molar ratio of glycine to hydrochloric acid in the curve (a) was 1: 1.

As is clear from the above, in the present invention, the esterification conversion rate is 98% without using an excessive acid catalyst as in the conventional method.
It can be at least%.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the flow of the amino acid esterification reaction by the device of the present invention, FIG. 2 is an explanatory view showing the flow of the amino acid esterification reaction by the conventional device, and FIG. 3 is a graph showing the esterification conversion rate of glycine. (Wherein the vertical axis is the esterification conversion rate and the horizontal axis is the reaction time), curve (a) is the esterification conversion rate by the apparatus of the present invention, and curve (b) is the graph showing the esterification conversion rate by the conventional apparatus, FIG. Shows the esterification conversion rate of glycine by the device of the present invention (esterification conversion rate on the vertical axis, reaction time on the horizontal axis), and the curve (a) shows the case where the molar ratio of glycine and hydrochloric acid is 1: 1. The glycine esterification conversion curve (b) is a graph showing the glycine esterification conversion when the molar ratio of glycine to hydrochloric acid was 1: 4. DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Distillation tower, 3 ... Separation tower, 11 ... Permeation apparatus, 12 ... Water selective permeation membrane, 13 ... Supply chamber, 14 ... Permeation chamber, 15 ... Decompression pump.

Claims (3)

[Claims] 1. A liquid containing an amino acid ester compound obtained by esterifying an amino acid in the presence of an alcohol and an acid catalyst in a reaction tank is introduced into a supply chamber of a pervaporation apparatus divided by a water selective permeable membrane, and the pressure is reduced. In the permeation chamber of the pervaporation apparatus, the reaction product water in the amino acid ester compound-containing liquid is selectively permeated through the water-selective permeable membrane as water vapor for dehydration, and the reaction product water is removed to remove the amino acid ester compound-containing liquid. The amino acid esterification reaction device, which is circulated in the reaction tank for carrying out the amino acid esterification reaction, and then again flows into the supply chamber of the pervaporation device. 2. A water-selective permeable membrane comprising acetic acid cellulose membrane, acetic acid cellulose derivative membrane, tetrafluoroethylenepolyvinylpyrrolidone membrane, tetrafluoroethylenepolyvinylgraft polymer membrane, polyvinyl alcohol membrane, cuprophane membrane. The amino acid esterification reaction device according to claim 1, wherein a sulfonated ethylene-ethyl acrylate membrane or an ion exchange membrane made of a styrene-based / silicon-based / ethylene-based material is used. 3. The amino acid esterification reaction device according to claim 1, wherein a cationic ion exchange membrane is used as the water-selective permeable membrane.