JPH03118346A - Production of ester - Google Patents

Abstract

PURPOSE:To make an effective reaction for obtaining an ester without the need for any fractionating column in such a way that a reflux fluid is allowed to fall on a umbrella attached to an agitating shaft in the vapor phase section in a reaction vessel and made into a thin-layered form, which is then dispersed dropwise from the edge of said umbrella into the vapor phase section. CONSTITUTION:In a reaction vessel 11, liquid phase reaction is made between an alcohol and an organic acid by agitating an agitator with agitating blades 14 dipped into the liquid phase section 13 of the agitating shaft 12 extending in the axial direction of said reaction vessel. Thence, the water as a byproduct is introduced, in combination with an excess amount of the alcohol or the organic acid, from the reaction vessel 11 into a heat exchanger 15, and the water is condensed and separated with a decanter 16, and the resulting fluid is returned to the reaction vessel 11 as reflux fluid. At this time, this reflux fluid is allowed to fall on a radially extending umbrella 18 attached to the agitating shaft 12 in the vapor phase section 17, and returned to the reaction mixture as a liquid phase. Thus, the reflux fluid, through the revolution of the shaft 12, is converted to a thin-layered form on the umbrella 18 and can be dispersed dropwise from the edge of the umbrella 18 into the vapor phase section, thereby, achieving high yield and high reaction rate equal to or greater than the case with the use of a fractionating column.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing esters.

(Prior art) As is well known, the reaction to produce esters from alcohol and organic acid is an equilibrium reaction, so in order to obtain high yield and high reaction rate, catalysts are used and other methods are used. ,
Usually, alcohol or organic acid is used in excess, and if necessary, an inert solvent is used. In particular, when water produced by the reaction (hereinafter referred to as produced water) accumulates in the reaction mixture, the reaction rate decreases, so it is necessary to efficiently remove the produced water from the reaction system.

Generally, in an industrial esterification reaction, an organic acid and an alcohol are reacted in a liquid phase, and as shown in FIGS. 1 and 2, excess alcohol or organic acid and/or The inert solvent vapor is guided from the reaction vessel 1 to the heat exchanger 2 and condensed, and the water is transferred to the decanter 3.
After separation, the alcohol or organic acid and/or
Alternatively, a method is known in which an inert solvent (hereinafter sometimes referred to as reflux liquid) is circulated into the reaction vessel 1. According to the method shown in FIG. 1, the reflux liquid is directly returned to the reaction vessel 1. According to the method shown in FIG. 2, it is returned to the reaction vessel 1 through a rectification column 4.

However, as shown in Figure 1, according to the method of directly returning the reflux liquid to the reaction vessel, the reflux liquid contains water in a saturated state, and therefore the esterification reaction rate is low and the reaction rate is also low. . On the other hand, according to the method using a rectification column shown in Figure 2, the water content of the reflux liquid can be kept low, but the space required to install the rectification column, the equipment cost, and the reboiler are required. This requires the supply of thermal energy, etc., which increases manufacturing costs.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned problems in the conventional method for producing ester by esterification reaction. To provide a method for producing esters that can produce esters at a high yield by ensuring a reaction rate equal to or higher than that using a rectification column in a method of directly returning the esters to a reaction vessel. With the goal.

(Means for Solving the Problems) The present invention provides an organic acid in a reaction vessel, if necessary, in the presence of an inert solvent, while stirring with a stirrer equipped with a stirring shaft extending in the axial direction of the reaction vessel. and alcohol are reacted in a liquid phase, and along with the water produced by the reaction, excess alcohol or organic acid and/or inert solvent vapor is led from the reaction vessel to a heat exchanger to be condensed, and the water is transferred to a decanter. In the ester production method, the alcohol, organic acid and/or inert solvent are separated in a reaction vessel and then circulated through the reaction vessel. And/or the method is characterized in that an inert solvent is dropped onto the shade and circulated into the reaction vessel.

The method for producing ester of the present invention will be described below based on drawings showing examples.

As shown in FIG. 3, in the method for producing ester according to the present invention, the reaction vessel 11 is equipped with a stirring shaft 12 extending in the axial direction, and the alcohol and organic acid are inertly mixed as needed. In the presence of a solvent, while being stirred by a stirrer having stirring blades 14 in the liquid phase portion 13 of the stirring shaft 12,
The reaction is carried out in the liquid phase.

As mentioned above, the water produced by this esterification reaction is
Together with excess alcohol or organic acid and/or inert solvent, the reaction vessel 11 is led to a heat exchanger 15, where it is condensed, and after separating water in a decanter 16, the reflux liquid is transferred to the reaction vessel 11. will be returned to.

Here, in the manufacturing method of the present invention, a radially expanding cap-shaped body 18 is attached to the stirring shaft 12 of the gas phase section 17 of the reaction vessel 11, and the reflux liquid is poured onto this cap-shaped body for one day. It is allowed to fall back into the reaction mixture as a liquid phase.

According to the manufacturing method of the present invention, the reflux liquid is formed into a thin layer on the cap-like body by the rotation of the stirring shaft, and is dispersed into the gas phase portion from the periphery of the cap-like body in the form of droplets. Therefore, gas-liquid contact occurs with the vapor generated from the liquid phase, which is the reaction mixture in the reaction vessel, and a so-called rectification effect occurs, and the reflux liquid with a low water content is returned to the reaction mixture.As a result, It is possible to obtain a high yield and a high reaction rate equivalent to or higher than when using a rectification column.

Therefore, the cap-like body may have any shape as long as it can make the reflux liquid into a thin layer thereon and diffuse it into the gas phase from the periphery in the form of droplets, but for example, It can be a flat disk as shown in FIG. 4 or a cylinder as shown in FIG. The cap-like body may be a plate with a smooth surface, or may be a punched metal, a wire mesh, or the like in order to increase the gas-liquid contact area. Further, the number of stages of the cap-like body is not limited at all, and may be one stage or multiple stages.

After obtaining the esterification reaction product as described above, it is purified by a conventional method. For example, the system after the esterification reaction is neutralized with an alkali, the aqueous phase is separated, and further water is added for washing, followed by dehydration and dealcoholization. Further, if necessary, decolorization treatment may be performed using activated carbon, activated clay, or the like.

(Effect of the invention) As described above, according to the method for producing ester of the present invention,
The reflux liquid is dropped onto a cap-shaped body attached to the stirring shaft in the gas phase part of the reaction vessel, forming a thin layer, and then dispersed in the form of droplets from the periphery into the gas phase part of the reaction vessel. Without using a column, it is possible to obtain a reaction rate and reaction rate that are equivalent to or higher than when using a rectification column.

(Example) The present invention will be explained in detail below by way of examples.

Example 1 In a reactor system as shown in Fig. 1, 1 mole of phthalic anhydride and 2.5 moles of heptyl alcohol were mixed using a reaction vessel with a disc-shaped wire mesh cap attached to the stirring shaft. were reacted at 180-220°C under reduced pressure in the presence of a catalyst.

It took 3.1 hours for the reaction rate, determined from the acid value of the reaction mixture, to reach 99.8%.

A 10% aqueous sodium carbonate solution was added to the system after the esterification reaction, and the system was kept at a temperature of 90°C for 60 minutes.

After that, about half of the amount of water was added to the crude ester obtained by separating the aqueous phase, kept at 90°C for 60 minutes, and heated to 120°C under reduced pressure.
Purified ester was obtained by dehydration and dealcoholization at C.

Example 2 The reaction was carried out in the same manner as in Example 1, except that a cap made of punched metal was used. It took 3.2 hours for the reaction rate to reach 99.8%.

Thereafter, the treatment was carried out in substantially the same manner as in Example 1 to obtain a purified ester.

Comparative Example 1 As shown in Figure 1, when the reflux liquid was directly returned to the reaction vessel without using a rectification column, it took 4.5 hours for the reaction rate to reach 99.8%. Ta.

Comparative Example 2 As shown in FIG. 2, when the reflux liquid was returned to the reaction vessel using a rectification column, it took 362 hours for the reaction rate to reach 99.8%.

As is clear from the above results, according to the method of the present invention, the reaction rate reaches 99.8% in almost the same reaction time as when using a rectification column, which is advantageous. .

[Brief explanation of drawings]

Fig. 1 shows a conventional esterification reactor system in which the reflux liquid is returned directly to the reaction vessel, Fig. 2 shows a conventional esterification reactor system in which the reflux liquid is returned to the reaction vessel via a rectification column, and Fig. 3 The diagram is
FIG. 4 is a diagram showing an esterification reactor system including a reaction vessel equipped with a cap used in the method of the present invention, and FIGS. 4 and 5 are diagrams showing examples of the cap. DESCRIPTION OF SYMBOLS 1... Reaction container, 2... Heat exchanger, 3... Decanter 4... Rectification column, 11... Reaction container, 12...
Stirring shaft, 13... Liquid phase part, 14... Stirring blade, 15.
... Heat exchanger, 16 ... Decanter 117 ... Gas phase part, 18 ... Shade-shaped body.

Claims (1)

[Claims] (1) While stirring with a stirrer equipped with a stirring shaft extending in the axial direction of the reaction vessel, the organic acid and alcohol are reacted in a liquid phase in the reaction vessel, optionally in the presence of an inert solvent. At the same time, along with the water produced by the reaction, excess alcohol or organic acid and/or inert solvent vapor is led from the reaction vessel to a heat exchanger and condensed, and after separating the water in a decanter, the alcohol or organic acids and/or
Alternatively, in an ester production method in which an inert solvent is circulated through a reaction vessel, a shade is attached to the stirring shaft in the gas phase of the reaction vessel, and the alcohol or organic acid and/or inert solvent is poured onto the shade. 1. A method for producing ester, which comprises dropping the ester into water and circulating it in a reaction vessel.