JPH08308588A - Condensation reaction using biocatalyst - Google Patents

Abstract

PURPOSE: To proceed smoothly a condensation reaction by stabilizing the amount of reflux of a reaction liquor through change in reaction pressure and by rapidly discharging byproducts from the reaction system without biocatalyst deactivation. CONSTITUTION: First, a reaction solvent higher in boiling point than byproducts is mixed with feedstocks and a biocatalyst, and a reaction vessel 1 is charged with the resultant mixture via a line 27 and a reaction is conducted under boiling at a temperature lower than the deactivation temperature of the biocatalyst. Secondly, the steam generated is partially condensed by a condenser 2, the resultant condensate as the reaction solvent is refluxed via a storage tank 3 to the reaction vessel 1, and the uncondensed steam is condensed by a condenser 4 and discharged out of the system. Finally, the reflux amount of the reaction solvent is detected using a flowmeter 1 and when the amount of reflux falls off a specified range, the reaction pressure is kept lower than a specified level to restore the amount of reflux within the specified range.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a condensation reaction method using a biocatalyst.

[0002]

2. Description of the Related Art Conventionally, one or more reaction raw materials have been used.
A method of conducting a condensation reaction using a biocatalyst such as an enzyme or a microorganism is widely known. For example, as such a condensation reaction, a reaction of condensing methyl glucoside and a fatty acid methyl ester in the presence of an enzyme, a reaction of condensing a fatty acid methyl ester and a polyhydric alcohol in the presence of an enzyme, and the like are known. Has been. By the way, in the condensation reaction using such a biocatalyst, from the viewpoint of the life of the biocatalyst,
The use of higher temperatures is not preferred and there is a limit on the upper limit of the reaction temperature. On the other hand, the reaction temperature is preferably as high as possible from the viewpoint of reaction rate. Further, it is preferable that the by-product having a low boiling point, which is a by-product of the condensation reaction, is promptly discharged out of the reaction system in relation to the reaction equilibrium. From these points, in an actual condensation reaction using a biocatalyst, a method of controlling the pressure and temperature of the reaction system to be constant and performing the reaction while refluxing the reaction solution is generally adopted. However, in such a method in which the reaction is carried out at a constant temperature and pressure of the reaction system, the composition of the reaction solution changes as the reaction progresses, and the boiling point of the reaction solution fluctuates toward the high temperature side. Without it, smooth removal of by-products from the reaction system becomes impossible. On the other hand, in order to stabilize the reflux amount of the reaction solution, the pressure was kept constant and the reaction temperature was controlled. In this case, when the reaction temperature became low, the reaction did not proceed smoothly and the reaction temperature became high. Sometimes the problem of deactivation of biocatalysts arises. As described above, the conventional condensation reaction method using a biocatalyst has not been industrially satisfactory.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a condensation reaction method using a biocatalyst, which allows the reaction to proceed smoothly without deactivating the biocatalyst.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a condensation reaction method in which one or more reaction raw materials are subjected to a condensation reaction in the presence of a biocatalyst and in the presence of a reaction solvent, and by-products having a boiling point lower than that of the reaction raw materials are produced. In (i) using a reaction solvent having a boiling point higher than that of the by-product, (ii) heating the reaction mixture containing the reaction raw material, the biocatalyst and the reaction solvent to a predetermined temperature lower than the deactivation initiation temperature of the biocatalyst. , Reacting while boiling, (iii) the vapor generated by boiling the reaction mixture is withdrawn from the reaction system, cooled and partially condensed, from a condensate mainly composed of a reaction solvent and mainly by-products. And (iv) refluxing the condensate obtained by the partial condensation to the reaction system,
(V) Completely condensing the uncondensed vapor obtained in the partial condensation, (vi) Detecting the reflux amount of the condensate to the reaction system, (vii) Detecting the reaction pressure, and setting the set pressure. Holding, (viii) when the reflux amount of the condensate falls below the set range due to the passage of reaction time, the reaction pressure is set to be lower than the set pressure when the reflux amount is within the set range. There is provided a condensation reaction method using a biocatalyst, which is characterized in that the pressure is maintained and the reflux amount is again maintained within a set range.

The condensation reaction method of the present invention is carried out under the conditions of a reaction mixture consisting of a reaction raw material, a biocatalyst and a reaction solvent, at a reaction temperature and a reaction pressure lower than atmospheric pressure in a range that does not cause deactivation of the biocatalyst. To be done. Typical reaction temperature is 3
It is 0 to 100 ° C., and the general reaction pressure is 200 Torr or less.

As the reaction solvent, a high boiling point organic solvent having a boiling point higher than that of the by-product, preferably a boiling point higher than that of the by-product by 30 ° C. or higher, more preferably 50 ° C. or higher is used. Examples of such a high boiling point organic solvent include acetylacetone, γ-butyrolactone, ethylene carbonate, propylene carbonate, α-picoline, β-picoline, γ-picoline, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, and 2 -Vinylpyridine, 4-vinylpyridine, 2-isopropylpyridine, N, N-dimethylpropionamide, N, N-dimethylbutyric acid amide, N, N-
Dimethylvaleric acid amide, N, N-capronamide, N,
N-methylethylacetamide, N, N-methylethylpropionamide, N, N-diethylformamide,
Examples thereof include N, N-dipropylformamide, N, N-dipropylacetamide and the like. When two or more components are used as reaction raw materials, one reaction component may be added in excess of the reaction equivalent to serve as a reaction solvent. The reaction solvent is used in an amount of 0.05 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 1 part by weight of the reaction raw material.

The biocatalyst includes an enzyme and a microorganism (bacteria), and an appropriate one is selected and used according to the type of reaction, and in many cases, one supported on a carrier is used. The ratio of the biocatalyst used was 0.
The proportion is 001 to 10 parts by weight, preferably 0.003 to 5 parts by weight.

The condensation reaction of the present invention includes various conventionally known condensation reactions (including transesterification reaction) which can be carried out using a biocatalyst. In this condensation reaction, a compound having a lower boiling point than the reaction raw material is produced as a by-product, and a condensation reaction product is produced as a target product. In this case, by-products include not only organic compounds such as lower alcohols but also inorganic substances such as water.

The following is an example of a condensation reaction carried out using a biocatalyst. (1) Condensation reaction of glucose and alcohol The reaction in this case can be performed using an enzyme as a biocatalyst, and the reaction formula is as follows. _{C 6 H 12 O 6 + ROH} → RO-C 6 H 11 O 5 + H 2 O (R: alcohol residue) (2) condensation reaction reaction in this case the methyl glucoside and a higher alcohol or polyhydric alcohol biocatalyst Can be carried out using an enzyme, and the reaction formula is as follows. _{CH 3 O-C 6 H 11} O 5 + ROH → RO-C 6 H 11 O 5 + C
H ₃ OH (R: higher alcohol or polyhydric alcohol residue) (3) Condensation reaction (esterification reaction) of a higher fatty acid or its lower alkyl ester with a monohydric or polyhydric alcohol It can be carried out using an enzyme, and its reaction formula is as follows. R ¹ COOR ² + ROH → R ¹ COOR + R ² OH (R ¹ : higher alkyl group, R ² : hydrogen or lower alkyl group, R: alcohol residue) (4) Alkyl glucoside or glucose and fatty acid or lower alkyl ester thereof Condensation reaction (esterification reaction) The reaction in this case can be carried out using oxygen as a biocatalyst, and its reaction formula is as follows. ^{_{R 3 O-C 6 H 11}} O 5 ( or _{C 6 H 12 O 6) +} R 1 COOR 2
_{^{→ R 3 O-C 6 H}} 11 O 4 -OCOR 1 ( or C ₆ H ₁₁ O ₅ -O
COR ¹ ) + R ² OH (R ¹ : higher alkyl group, R ² : hydrogen or lower alkyl group, R ³ : alkyl group)

Next, the present invention will be described with reference to the drawings.
FIG. 1 shows a flow sheet for carrying out the method of the present invention.
Here is an example. In FIG. 1, 1 is a reactor, 2 is a first condenser, 3 is a condensate storage tank, 4 is a second condenser, 5 is a controller,
6 indicates a vacuum pump, TC indicates a temperature controller, PC indicates a pressure controller, and FI indicates a flow rate measuring device.

A stirrer 7 is provided inside the reactor 1,
It is rotated by the motor 8. A heating coil 9 is arranged on the inner peripheral wall surface of the reactor 1 so that it can be heated by steam. In the reaction, first, the reaction raw material, the reaction solvent and the biocatalyst are filled in the reactor. These fillings can be done through line 27 and valve 28. Next, the agitator 7 in the reactor 1 is rotated, and steam is supplied to the heating coil 9 attached to the reactor 1 through the line 13, the valve 14 and the flow rate adjusting valve 15 to heat the contents of the reactor. Then, by further driving the vacuum pump 6, the inside of the reactor 1 and the first condenser 2
And the inside of the second condenser 4 are kept under reduced pressure.

In the present invention, the reaction temperature (temperature of the contents of the reactor) and the reaction pressure (pressure of the space inside the reactor) are
Both are set to a predetermined temperature and pressure. The reaction temperature can be maintained at the set temperature by controlling the amount of steam flowing through the flow rate control valve 15 by the temperature controller TC connected to the temperature detector 10. The reaction pressure can be maintained at the set pressure by the pressure regulator PC connected to the controller 5 and the pressure regulating valve 25 while being connected to the pressure detector 10 '. The reaction temperature in this case is a temperature in a range that does not deactivate the biocatalyst and allows the reaction to proceed smoothly, and is, for example, 1 to 30 ° C. lower than the deactivation start temperature of the biocatalyst, preferably 5 to 2
0 ° C lower temperature. On the other hand, the reaction pressure is a pressure at which the reactor contents (reaction liquid) are boiled at the reaction temperature and the reflux amount of the condensed liquid from the first condenser 2 to the reactor 1 is maintained within a predetermined range. The deactivation initiation temperature of the biocatalyst is a temperature higher than the temperature at which the biocatalyst exhibits maximum activity, and the lowest temperature at which the activity is 97% or less of the maximum activity.

The inside of the reactor 1 is kept under the above-mentioned reaction temperature and reaction pressure, and the reaction liquid is kept in a boiling state. In the condensation reaction method of the present invention, a reaction mixture (reaction liquid)
Reacts in this boiling state to produce a by-product having a lower boiling point than the reaction raw material together with the desired condensation reaction product.
The vapor generated by the boiling of the reaction liquid mainly consists of the reaction solvent and by-products, and is introduced into the first condenser 2 through the line 16.

As the first condenser 2, a conventionally known heat exchanger having a structure for indirectly contacting gas and liquid can be used. The one shown in FIG. 1 has a plurality of cooling tubes inside,
The structure is such that steam contacts the outer surface of the cooling pipe. The cooling water is introduced into the condenser through the line 18 and the valve 19, flows through the cooling pipe, and then is discharged from the condenser through the line 20. The steam introduced into the condenser through the line 16 comes into contact with the outer surface of the cooling pipe to be partially condensed, and a condensate mainly composed of a reaction solvent and an uncondensed steam mainly composed of a by-product. Is generated. The uncondensed vapor is introduced into the second condenser 4 through the line 17, while the condensate produced in the first condenser 2 is introduced into the condensate storage tank 3.

The condensation temperature (cooling temperature) of the vapor in the first condenser 2 is the reaction solvent under the pressure conditions in the condenser,
Based on the gas-liquid equilibrium value of the by-products, raw materials, and products, the temperature is set within a range in which the loss of the reaction solvent, the raw materials, and the products is small, and the by-products can be efficiently removed as vapor.

As the second condenser, it is possible to use a heat exchanger having a structure for indirectly contacting gas and liquid, a gas-liquid contact device or the like. What is shown in FIG. 1 is a plate type heat exchanger, in which cooling water is introduced into the apparatus through a line 20 and a valve 21, and is discharged through a line 29. On the other hand, the uncondensed vapor introduced into the apparatus through the line 17 condenses on the plate surface and is discharged through the lines 22 and 23. A vacuum line 24 is connected to the line 22, and the vacuum line is connected to the vacuum pump 6 through a pressure control valve 25. The condensate generated in the first condenser 2 is temporarily stored in the storage tank 3 and then the line 26
And is refluxed into the reactor 1.

As described above, when the condensation reaction is carried out at a predetermined reaction temperature and a predetermined reaction pressure while boiling the reaction liquid in the reactor and refluxing the condensate into the reactor, The composition of the reaction liquid varies with the progress of the reaction due to the addition of solvent loss and the like, the boiling point of the reaction liquid rises, and accordingly, the reflux amount of the condensate passing through the line 26 gradually decreases. The reduction of the reflux amount means that the evaporation amount of the reaction solvent from the reaction solution is reduced and it becomes difficult to distill the by-product from the reactor smoothly.

In the present invention, the reflux amount of the condensate to the reactor is measured, and when the reflux amount decreases from the set range due to the progress of the reaction, the reaction pressure is set within the set range. Set pressure at a certain time (1st set pressure)
The second set pressure lower than the above is set. Further, when the reflux amount decreases below the set range as the reaction progresses, the reaction pressure is set to the third set pressure lower than the second set pressure. Such a changing operation of the set pressure is sequentially performed to complete the condensation reaction.

Fluctuations in the set reaction pressure include a flow rate measuring device FI for measuring the reflux amount of the condensate, a pressure controller PC for adjusting the pressure in the reactor to a set pressure, and a pressure adjusting valve 25.
Can be performed using the controller 5. That is, an electric signal of the reflux amount obtained by the flow rate measuring device FI is sent to the controller 5, and in this controller 5, the set pressure value of the pressure regulator PC is set based on the predetermined relationship between the reflux amount and the reaction pressure. Is converted to a predetermined value and converted into an electric signal for setting, and this electric signal is sent to the pressure controller PC, and the pressure controller PC
Change the set pressure value of to a new lower pressure set value. The reaction pressure is kept at this newly set pressure value by the action of the pressure regulator PC set to this new pressure value and the pressure regulating valve 25 connected thereto. A computer can be used as the controller 5.

The controller 5 stores the relationship between the reflux amount that gradually decreases with the passage of the reaction operation time and the reaction pressure necessary to increase the reduced reflux amount to the set value again. FIG. 2 shows an explanatory diagram for controlling the reflux amount using the relationship between the reaction operation time, the reflux amount and the reaction pressure. In FIG. 2, point a-1 indicates the set reflux amount at the start of the reaction, and point b-1 indicates the set lower limit value of the reflux amount.
The range between the points a-1 and b-1 indicates the set range (fluctuation range) of the reflux amount. The reaction pressure while the reflux amount is decreasing from the point a-1 to the point b-1 is set to the first set value P-I. When the reflux amount decreases from the point a-1 to the point b-1, the reaction pressure is set to the second set value P-II which is lower than the first set value PI. As a result, the reflux amount increases from the point b-1 to the point a-2, and gradually decreases as the reaction operation time elapses. When the reflux amount is reduced to point b-2, the reaction pressure is set to a third set value P-III lower than P-II.
Set to. As a result, the reflux amount is from point b-2 to point a-3.
It increases to the point and gradually decreases as the reaction operation time elapses. The reaction pressure set values P-I, P-II, P
The specific value of -III varies depending on the condensation reaction system and cannot be uniquely determined, but can be determined by preliminary experiments or chemical engineering calculations. Also, P-I and P-
It is also possible to predetermine the differential pressure portion of II and calculate the pressure value to be set next from the first pressure setting value in the controller 5. In addition, in FIG.
1, a-2, a-3 points and b-1, b-2 and b-
Although each point of 3 is set to the same value, it does not necessarily have to be set to the same value, and may be within the upper and lower limits of the set range of the reflux amount. The controller 5 determines the relationship between the reaction pressure and the reflux amount shown in FIG. 2 or the value of the differential pressure when the pressure is reduced.
By storing it in the
The reaction pressure can be sequentially decreased to a preset set value as the reaction operation time elapses.

FIG. 3 shows another explanatory diagram for controlling the reflux rate by using the relationship between the reaction operation time, the reflux rate and the reaction pressure. A horizontal line X in FIG. 3 indicates a desired set value of the reflux amount, a horizontal line Y indicates a set lower limit value of the reflux amount, and a horizontal line Z indicates a set upper limit value of the reflux amount. The set range (variation range) of the reflux amount is shown between Z and Y. Also, c-1, c-2, c-3
And c-4 are ΔT (1) and ΔT, respectively.
The average values of the reflux amounts in the time intervals of (2), ΔT (3), and ΔT (4) are shown. The time interval ΔT is 10 minutes or less,
It is preferably 3 minutes or less. A method of controlling the reflux amount using the relationship between the reaction operation time, the reflux amount, and the reaction pressure shown in FIG. 3 is shown. When the reaction operation time is ΔT (1), the average value at the ΔT (1) time is shown. The reflux amount c-1 is calculated. In this case, the average reflux amount at ΔT (1) is c
Since it is not lower than the -1 setting lower limit value Y, the operation for resetting the reaction pressure to be low is not performed. Next, the same operation is performed at the time intervals ΔT (2) and ΔT (3) in the reaction operation time. Time interval ΔT (4) in reaction operation time
Since the average recirculation amount c-4 is lower than the lower limit value Y, the reaction pressure is set to a pressure T-II lower than T-I and the recirculation amount is increased to d-1. Thereafter, the reflux amount is set to the set value X every time the reaction operation time elapses for a fixed time.
Alternatively, the operation of increasing the value between Z and Y is repeated until the reaction is completed. The controller 5 can perform the above-described calculation of the average reflux amount each time the reaction operation time elapses for a certain period of time, operation of newly setting the reaction pressure based on the calculation result of the average reflux amount, and the like. When the reflux amount exceeds the upper limit Z due to abnormal reaction or poor temperature control, the pressure can be increased by the exact opposite operation to prevent excessive evaporation.

The control of the reflux amount by the reaction pressure of the present invention is as follows.
It can also be done manually. In this case, the controller 5
In addition to the buttons and dials for setting the reaction pressure for adjusting the set pressure in the pressure controller PC, while watching the measured value of the reflux amount by the flow rate measuring device FI,
When the reflux amount becomes lower than the set lower limit value, the reaction pressure is adjusted by using the reaction pressure setting button or dial so that the reflux amount falls within the set range. The set value of the reaction pressure set by the pressure regulator PC is a plurality of pressure values, P (1), P (2), P (3), P (n-
1) and P (n) are selected. In this case, the relationship between those pressure values is as follows. P (1)> P (2)> P (3)> P (n-1)> P
(N)

The number n and P (n-
The pressure difference Δp between 1) and P (n) is appropriately selected according to the type of condensation reaction. Also, P (n-1) and P (n-1)
The pressure difference ΔP between (n) is 0.01-5 Torr, preferably 0.05-1 Torr.

The adjustment of the reflux amount using the above-mentioned set pressure value is performed by measuring the reflux amount at the set value P (1) of the reaction pressure with the measuring instrument FI and observing the measured value of the reflux amount. Is lower than a predetermined lower limit value, the reaction pressure is newly set to P (2) to increase the reflux amount. Next, when the measured value of the reflux amount again falls below the set lower limit value due to the passage of the reaction time, the reaction pressure is newly set to P (3). Next, when the measured value of the reflux amount under the reaction pressure of P (n-1) falls below the lower limit of the setting due to the elapse of the reaction time, the reaction pressure is set to P.
Set new to (n). In this way, the condensation reaction can be allowed to proceed smoothly without constantly lowering the reflux amount below the set lower limit value.

The reflux amount of the condensate to be returned from the first condenser 2 to the reactor 1 is appropriately determined according to the type of condensation reaction, but generally, in the steady reaction state, the reactor 1 is started at the start of the reaction. The amount is 10 to 100% by weight, preferably 20 to 60% by weight, per hour with respect to the total weight of the reaction mixture added to the. If the reflux amount is too small, the by-products cannot be smoothly discharged from the reactor, whereas if it is too large, the loss amount of the reaction solvent increases, which is disadvantageous. The set value of the reflux amount in the present invention is selected from the above-mentioned reflux amount range, and the lower limit value of the set reflux amount is selected to be lower than the reflux amount set value within the above-mentioned reflux amount range. The lower limit value of the recirculation amount is usually 70 to 99 of the recirculation amount setting value.
%, Preferably 80 to 95%.

As described above, the set value of the reaction pressure is a temperature close to the deactivation point of the biocatalyst at the start of the reaction or the initial stage of the reaction, usually 5 to 30 ° C. higher than the deactivation start temperature of the biocatalyst. The pressure is selected such that the reaction liquid boils at a temperature as low as possible. After the reaction is started, the set value of the reaction pressure is gradually and continuously, preferably intermittently changed by changing the set value of the pressure controller PC so that the reflux amount does not fall below the set lower limit value. Lower.

Next, the present invention will be described in more detail with reference to examples. Example 1 A condensation reaction (transesterification reaction) was performed according to the flow sheet shown in FIG. Reaction raw material Methyl glucoside 1 part by weight Methyl caprylate 2.5 parts by weight Reaction solvent β-picoline (boiling point: 144 ° C.) 2 parts by weight Biocatalyst Oxygen (Candida antarctica-derived neutral heat resistant lipase in acrylic resin) Immobilized: immobilized lipase, manufactured by NOVO Co., deactivation start temperature of 80 ° C. or higher) 0.05 part by weight was added to the reactor 1 (volume: 200 liters) so that the total amount became 100 kg. The product of this reaction is caprylic acid ester of methyl glucoside, and the by-product is methanol (boiling point: 64.7 ° C). Then, while stirring, use a temperature controller TC and steam at 70 ° C.
After heating, the reactor internal pressure was lowered to 33.5 torr and reaction control was started. The condensate (reaction solvent) reflux rate is the average reflux rate per minute, and the target value is 45 kg / hr, which is 45% of the total weight of the reaction raw materials, and the lower limit value is 40 kg / hr and the upper limit value is 40 kg / hr. The control was performed by setting it to 50 kg / hr. Further, the pressure set value was set to be lowered by 0.1 torr when the reflux amount was below the lower limit value. The reaction temperature was controlled by the temperature controller TC so that it was always 70 ° C. The condensation temperature of the first condenser was 25 ° C. Table 1 shows the reaction operation time, the pressure setting value and the reflux amount. It was confirmed that the conversion rate (reaction rate) of methyl glucoside to caprylic acid ester of methyl glucoside after performing the reaction for 360 minutes was 95% or more. In addition, as a result of using the used enzyme in the repeated reaction, it was confirmed that the reaction rate was 95% or more in the reaction time of 360 minutes even in the repeated reaction, and it became clear that the reaction rate can be secured while suppressing the inactivation of the enzyme. It was

[0028]

[Table 1]

[0029]

According to the present invention, byproducts can be promptly discharged from the reaction system without deactivating the biocatalyst, and the condensation reaction can proceed smoothly.

[Brief description of drawings]

FIG. 1 shows an example of a flow sheet for carrying out the condensation reaction method of the present invention.

FIG. 2 is an explanatory diagram for controlling the reflux rate using the relationship between the reaction operation time, the reflux rate and the reaction pressure.

FIG. 3 shows another explanatory diagram for controlling the reflux rate by using the relationship between the reaction operation time, the reflux rate and the reaction pressure.

[Explanation of symbols]

 1 Reactor 2 1st condenser 3 Condensate storage tank 4 2nd condenser 5 Controller 6 Vacuum pump TC Temperature controller PC Pressure controller FI Flow rate measuring device

Claims (1)

[Claims] 1. A condensation reaction method in which one or more reaction raw materials are subjected to a condensation reaction in the presence of a biocatalyst and in the presence of a reaction solvent, and a by-product having a boiling point lower than that of the reaction raw materials is produced. i) using a reaction solvent having a boiling point higher than that of the by-product; (ii) heating the reaction mixture containing the reaction raw material, the biocatalyst and the reaction solvent to a predetermined temperature lower than the deactivation initiation temperature of the biocatalyst, and boiling it. (Iii) The vapor generated by boiling of the reaction mixture is withdrawn to the outside of the reaction system, cooled and partially condensed, and a condensate mainly composed of a reaction solvent and an uncondensed mainly composed of a by-product. (Iv) refluxing the condensate obtained by the partial condensation to the reaction system, (v) completely condensing the uncondensed vapor obtained in the partial condensation, (vi) the above Anti-condensate Detecting the amount of reflux to the reaction system, (vii) detecting the reaction pressure and holding it at a set pressure, (viii) when the amount of reflux of the condensate drops below the set range due to the passage of reaction time, Condensation using a biocatalyst, characterized in that the reaction pressure is held at a pressure set lower than the set pressure when the reflux amount is within the set range, and the reflux amount is held again within the set range. Reaction method.