CN102977069A - The manufacture method of cyclic formal - Google Patents

Abstract

The invention provides a method for producing cyclic formal. The present invention is used to produce high-purity cyclic formal with reduced amount of waste generated when producing cyclic formal and having few side components. A method for producing a cyclic formal, comprising reacting an alkylene glycol and a formaldehyde derivative in the presence of an acid catalyst to obtain a cyclic formal mixture and purifying the cyclic formal mixture, The above production method is characterized in that it further includes the step of purifying the alkylene glycol-containing mixture obtained in the step of purifying the cyclic formal mixture and supplying it to the purification process of the cyclic formal mixture. in the process.

Description

The manufacture method of cyclic formal

technical field

The present invention relates to the preparation method of cyclic formal.

Background technique

Cyclic formal refers to, for example, 1,3-dioxolane, 1,4-butanediol formal, diethylene glycol formal, 4-methyl-1,3-dioxolane , 1,3-dioxane, 1,3,5-trioxepane, etc. Cyclic formals are used, for example, as solvents for fats and oils, extractants, intermediates for pharmaceuticals, raw materials for resin materials, and the like.

The aforementioned cyclic formal can be produced, for example, by a cyclization reaction between an alkylene glycol and an aldehyde. As a method for producing cyclic formal (a representative example is 1,3-dioxolane), for example, the production methods described in Patent Documents 1 to 5 have been proposed. Specifically, for example, according to the method described in Patent Document 1, the cyclic formal obtained by the reaction of an alkylene glycol and a formaldehyde derivative is brought into countercurrent contact with a diluent (pure water, etc.) in a distillation column, thereby , the cyclic formal can be purified by absorbing unreacted formaldehyde derivatives, and the alkylene glycol can be charged into another distillation column, whereby the water present in the cyclic formal can be absorbed and separated.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 4245921 (Chinese Patent No. CN1197858C)

Patent Document 2: Japanese Patent No. 3098300

Patent Document 3: Japanese Patent Application Laid-Open No. 8-012667

Patent Document 4: Japanese Patent Application Laid-Open No. 9-048774

Patent Document 5: Japanese Patent No. 3474252

Contents of the invention

The problem to be solved by the invention

In the fields where the above-mentioned cyclic formals are applied, oil solvents, extractants, pharmaceutical intermediates, and raw materials for resin materials, etc., high-purity cyclic formals have been sought. In the techniques of Patent Documents 1 to 5, attempts to improve the purity have also been made. For example, Patent Document 1 discloses a method such as regulating the ratio of the amount of the raw material alkylene glycol to the formaldehyde derivative. Cyclic formals obtained by this technique are of very high purity. On the other hand, in the field of using cyclic formal as a raw material, there is an increasing demand for high purification. For example, for polyacetal resins that use 1,3-dioxolane as one of the cyclic formals as a raw material, in the fields of automobile parts and the like to which the above-mentioned polyacetal resins are applied, low volatility The requirements for high purity have increased, and subsequently, the requirements for high purity of raw materials have also increased. Therefore, cyclic formals having higher purity than cyclic formals obtained by the techniques of Patent Documents 1 to 5 have been sought.

In order to increase the purity of the cyclic formal, for example, a method of further purifying the obtained cyclic formal is considered, but in this method, the waste of the substance used for purification (such as water) will increase, so It cannot be said to be an efficient method. Therefore, a method for efficiently obtaining cyclic formal with higher purity has been sought.

An object of the present invention is to provide a method for economically producing high-purity cyclic formal while reducing side components further efficiently.

means of solving problems

The inventors of the present invention conducted in-depth research on a method for further efficiently reducing by-products and producing high-purity cyclic formal economically and efficiently. As a result, they found that, in the production process of cyclic formal, Purifying the mixture containing alkylene glycol produced in the purification process of the mixture and supplying it to the process of purifying the cyclic formal mixture can further efficiently reduce side components and reduce waste, thereby enabling economical Obtain high-purity cyclic formal, and then complete the present invention. That is, the present invention is as follows.

[1] A method for producing a cyclic formal, comprising the steps of reacting an alkylene glycol and a formaldehyde derivative in the presence of an acid catalyst to obtain a cyclic formal mixture and purifying the cyclic formal mixture The process of said manufacturing method is characterized in that,

It also has the following procedures:

The mixture containing alkylene glycol obtained in the step of purifying the cyclic formal mixture is purified and supplied to the step of purifying the cyclic formal mixture.

[2] The method for producing a cyclic formal according to [1], wherein the step of purifying the cyclic formal mixture includes a step of removing formaldehyde derivatives and a step of removing water.

[3] The method for producing cyclic formal as described in [1], wherein in the step of purifying the mixture containing alkylene glycol, the components distilled from the top of the purification tower The components distilled from the bottom of the purification column are supplied to the step of purifying the cyclic formal mixture, respectively.

[4] The method for producing cyclic formal as described in [2], wherein in the step of purifying the mixture containing alkylene glycol, the components distilled from the top of the purification tower It is supplied to the step of removing formaldehyde derivatives from the cyclic formal mixture, and the component distilled from the bottom of the purification tower is fed to the step of removing water.

[5] The method for producing cyclic formal as described in [2], wherein in the step of purifying the mixture containing alkylene glycol, the components distilled from the top of the purification tower It is supplied to the cyclic formal mixture, and the component distilled from the bottom of the purification column is supplied to the step of removing water.

[6] The method for producing cyclic formal according to any one of [1] to [5], wherein ethylene glycol is supplied to the mixture containing alkylene glycol or the mixture containing The mixture of alkylene glycols is in the process of purification.

[7] The method for producing cyclic formal as described in [1], wherein in the step of purifying the mixture containing alkylene glycol, the temperature at the bottom of the purification tower is 190° C. to 190° C. 210°C.

Invention effect

According to the method for producing cyclic formal of the present invention, by-components can be reduced more efficiently, waste can be reduced, and high-purity cyclic formal can be obtained economically.

Description of drawings

FIG. 1 is a schematic diagram of an apparatus for producing cyclic formal used in Examples 1 to 3. It should be noted that each figure only shows main equipment, and auxiliary equipment is omitted.

FIG. 2 is a schematic diagram of an apparatus for producing cyclic formal used in Example 4. FIG.

FIG. 3 is a schematic diagram of an apparatus for producing cyclic formal used in Example 5. FIG.

FIG. 4 is a schematic diagram of a production apparatus for cyclic formal used in Comparative Examples 1 to 2. FIG.

Label description

1. Purification tower (Ⅱ-1)

2. Purification tower (Ⅱ-2)

3. Purification tower (Ⅲ)

4. Mixture (A)

5. Mixture (B)

6. Mixture (C)

7. Mixture (D)

8. Mixture (E)

9. Mixture (F)

10. Mixture (G)

11. water

12. Ethylene glycol

Detailed ways

Hereinafter, a mode for implementing the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to the present embodiment described below. Various modifications can be made to the present invention without departing from the gist thereof.

The manufacturing method of the cyclic formal of the present embodiment comprises:

(Step I) a step of reacting an alkylene glycol and a formaldehyde derivative in the presence of an acid catalyst to obtain a cyclic formal mixture (A), and

(Step II) a step of purifying the obtained cyclic formal mixture (A),

The manufacturing method is characterized in that it also has the following steps:

(Step III) The mixture containing alkylene glycol obtained in the step (Step II) of purifying the mixture (A) containing cyclic formal is purified and supplied to the mixture (A) containing cyclic formal. ) in the purification step (step II).

In this embodiment, the cyclic formal refers to a cyclic formal synthesized from an alkylene glycol and a formaldehyde derivative. Specific examples of the aforementioned cyclic formal include: 1,3-dioxolane, 1,4-butanediol formal, diethylene glycol formal, 4-methyl-1,3- Dioxolane, 1,3-dioxane, 1,3,5-trioxepane. The aforementioned cyclic formal can be produced by reacting an alkylene glycol and a formaldehyde derivative in the presence of an acid catalyst.

As an impurity accompanying in the process of producing a cyclic formal, 2-methyl cyclic formal is mentioned, for example. By reducing the amount of 2-methyl cyclic formal contained in cyclic formal, for example, when used as an auxiliary raw material for polyacetal resin, a high polymerization yield can be obtained, and polycondensation with excellent thermal stability can be obtained. Aldehyde resin.

Each step in the production method of the cyclic formal of the present embodiment will be described below.

Step I of the present embodiment is a step of reacting an alkylene glycol and a formaldehyde derivative in the presence of an acid catalyst to obtain a cyclic formal-containing mixture (A).

Examples of the alkylene glycol used in the present embodiment include ethylene glycol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol.

Examples of formaldehyde derivatives used in this embodiment include formaldehyde (formalin), paraldehyde, trioxane, tetraoxane, methylal, polyacetal, etc. or a mixture of them. Among the above formaldehyde derivatives, formaldehyde (formalin) and trioxane are preferably used.

Examples of the acid catalyst used in the present embodiment include inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid; organic acids such as sulfonic acid, phosphonic acid, and carboxylic acid; strongly acidic ion exchange resins, zeolites, silica, and alumina. Solid acid catalyst; heteropoly acids such as phosphomolybdic acid, phosphotungstic acid, etc. From the viewpoint of being able to easily remove and replenish the acid catalyst, it is preferable to use a liquid substance as the acid catalyst. Among them, sulfuric acid, strongly acidic ion exchange resins, and heteropolyacids can be preferably used. In addition, sulfuric acid is particularly preferable since it can make the decomposition rate of formaldehyde derivatives such as trioxane extremely fast compared with organic acids, and is in a liquid state.

The temperature conditions for reacting the alkylene glycol and the formaldehyde derivative in the presence of a catalyst vary depending on the raw material and the catalyst used, but it is necessary to set the temperature condition at which the formation reaction of the cyclic formal can proceed and maintain a predetermined temperature. Cyclic formal yields and yields within the temperature range. Furthermore, in this temperature range, in order to reduce the formation of impurities, it is preferable to carry out the reaction at a lower temperature. Taking the case of producing 1,3-dioxolane as an example, in order to suppress the formation of impurities such as acetaldehyde and 2-methyl-1,3-dioxolane, the reaction temperature is preferably 70 to 150 °C, more preferably 90 to 120 °C.

In addition, the pressure in the reaction tank is preferably a pressure at which most of the cyclic formal and water can be evaporated at the above reaction temperature, and may be either normal pressure or reduced pressure.

Step II of the present embodiment is a step of purifying the cyclic formal mixture (A) obtained in Step I. The cyclic formal mixture (A) contains, for example, unreacted formaldehyde derivatives and water associated with the reaction. Therefore, in order to obtain high-purity cyclic formal, it is necessary to separate and remove the above-mentioned unreacted formaldehyde derivative and water produced by the reaction, and in step II, purification for removing the above-mentioned side components is performed.

The step of purifying the cyclic formal mixture (A) preferably includes a step of removing formaldehyde derivatives (step II-1) and a step of removing water (step II-2), and is preferably carried out in different purification towers. . When performing this step using a purification column, it is preferable to use a sieve plate distillation column. By using a sieve plate distillation column, the purity of the obtained cyclic formal can be further improved.

In step II-1, formaldehyde derivatives are removed.

The cyclic formal mixture (A) is specifically a mixture containing cyclic formal, formaldehyde derivatives and water, which is sent into the purification tower (II-1), and the cyclic formal The mixture (B) of formal and water is separated from the mixture (G) containing formaldehyde derivatives. When water is supplied to the purification column (II-1) separately from the mixture, since this separation can be efficiently performed, it is preferable.

The number of stages of the purification column (II-1) is preferably 25 to 50 stages. More preferably, it is 20 to 40 stages, and even more preferably, it is 25 to 40 stages. Next, a case where the number of stages of the purification column (II-1) is 30 stages is taken as an example, and the supply stage of each mixture will be described. The supply section of the cyclic formal mixture (A) is preferably the 2nd to 20th section from the upper section of the purification tower (II-1), more preferably the 3rd to 15th section, and even more preferably the 5th section ~ Paragraph 15. In addition, when water is further supplied to the purification column (II-1), it is preferable to make the water supply stage be an upper stage than the mixture (A) supply stage. For example, when the supply stage of the mixture (A) is 15 stages from the upper stage, the water supply stage is preferably the upper stage higher than the 12 stage. In a more preferable supply stage, the supply stage of the mixture (A) is 10 stages from the upper stage, and the supply stage of water is 5 stages. By setting the water supply section above the mixture (A) supply section, the formaldehyde derivative can be easily separated in the purification column (II-1), and the purity of the cyclic formal can be further improved.

The mass ratio (R: mixture (A)/water) of the mixture (A) supplied to the purification column (II-1) to the supply amount of water is preferably in the range of 0.1 to 10, more preferably in the range of 0.5 to 5, More preferably, it is the range of 0.5-3. When the range of the mass ratio (R: mixture (A)/water) of the mixture (A) supplied to the purification column (II-1) to the supply amount of water is within the above range, it tends to be possible to produce a small amount of by-products and Cyclic formal with higher purity.

Regarding the temperature and pressure of the purification column (II-1), it is preferable that the temperature of the bottom of the purification column (II-1) is in the range of 80 to 130° C., and the pressure is in the range of 1 to 50 kPa. More preferably, the temperature at the bottom of the tower is in the range of 90° C. to 120° C., and the pressure is in the range of 10 to 40 kPa. More preferably, the temperature at the bottom of the tower is in the range of 90° C. to 110° C., and the pressure is in the range of 20 to 40 kPa. By setting the temperature and pressure at the bottom of the purification tower (II-1) within the above range, the temperature at the top of the purification tower (II-1) can be adjusted to a range of 60 to 90° C. High-purity cyclic formal with few products.

Next, in step II-2, water is removed.

Specifically, the mixture (B) containing cyclic formal and water obtained in the process II-1 is sent to the purification tower (II-2), and the water is removed in the purification tower (II-2) to obtain high-purity The cyclic formal (F). In the purification step, water tends to azeotrope with the cyclic formal compound, and it is difficult to purify only by distillation. Therefore, it is preferable to supply an alkylene glycol as an absorbent for water to the purification column (II-2) to make the water Absorbed by alkylene glycol and distilled. At this time, a mixture (C) containing alkylene glycol and water is obtained from the bottom of the purification column (II-2).

The number of stages of the purification column (II-2) is preferably 30 to 60 stages, more preferably 30 to 50 stages, and even more preferably 35 to 50 stages. Next, a case where the number of stages of the purification column (II-2) is 45 stages is taken as an example, and the supply stage of each mixture will be described. The supply section of the mixture (B) supplied to the purification tower (II-2) is preferably 10 to 40 sections from the upper section of the purification column (II-2), more preferably 20 to 40 sections, and even more preferably 25 to 40 sections. 35 paragraphs. The supply stage of the alkylene glycol is preferably 2 to 10 stages from the upper stage of the purification column (II-2), more preferably 2 to 8 stages, and even more preferably 2 to 5 stages. When the supply section is within the above range, it tends to be possible to produce cyclic formal with less by-products and higher purity.

Regarding the temperature and pressure of the purification column (II-2), it is preferable that the temperature at the bottom of the column is in the range of 130 to 180° C., and the pressure is in the range of 1 to 50 kPa. More preferably, the temperature at the bottom of the tower is in the range of 140 to 170° C., and the pressure is in the range of 10 to 40 kPa. More preferably, the temperature at the bottom of the tower is in the range of 150 to 170° C., and the pressure is in the range of 20 to 40 kPa. By keeping the temperature and pressure at the bottom of the purification tower (II-2) in the above range, the temperature at the top of the purification tower (II-2) can be adjusted to a range of 60 to 90°C, and by-products tend to be produced Less high-purity cyclic formal.

In step III of the present embodiment, the mixture (C) containing alkylene glycol obtained in the step (step II) of purifying the cyclic formal mixture (A) is purified and supplied to the cyclic formal mixture. (A) A step in the step of performing purification (step II).

By providing this step, the conventionally discarded mixture (C) can be effectively utilized, thereby not only reducing waste, but also surprisingly improving the purity of the cyclic formal.

Step III will be specifically described.

In step III, the mixture (C) containing the alkylene glycol obtained in step II is purified. This procedure is preferably carried out in a purification column. When performing this step using a purification column, it is preferable to use a sieve plate distillation column. By using a sieve plate distillation column, the purity of the obtained cyclic formal can be further improved.

The number of stages of the purification column (III) is preferably 10 to 30 stages, more preferably 15 to 30 stages, and even more preferably 15 to 25 stages. Next, the supply stages of the respective mixtures will be described taking a case where the number of stages of the purification column (III) is 20 stages as an example. The supply section of the mixture (C) supplied to the purification column (III) is preferably 1 to 20 sections from the upper section of the purification column (III), more preferably 1 to 15 sections, and more preferably 5 to 10 sections. part. When the supply section of the mixture (C) supplied to the purification column (III) is within the above range, it tends to be possible to produce cyclic formal with less by-products and higher purity.

The pressure of the purification tower (III) is 10~20MPa, preferably 15~18MPa. In addition, as for the temperature, the temperature at the bottom of the tower is preferably 180 to 210°C, more preferably 190 to 210°C, and even more preferably 195 to 205°C. When the temperature of the bottom of the purification column (III) is within the above range, the temperature of the top of the purification column (III) can be adjusted to 90° C. or higher, and high-purity cyclic formal with few by-products tends to be produced.

In addition, it is preferable to supply the alkylene glycol to the purification column (III) or to the mixture (C) supplied to the purification column (III). By supplying the alkylene glycol, the purification efficiency in the purification column (III) can be improved, and it tends to be possible to produce high-purity cyclic formal with few by-products.

Through the above-mentioned purification process, it is separated into component (D) distilled from the top of the purification tower (III) and component (E) distilled from the bottom of the purification tower (III), and in this embodiment, they are respectively supplied to In the step of purifying the cyclic formal mixture (A) (step II).

The supply position of the component (E) distilled from the bottom of the purification column (III) may be any position in the step II, but the step of removing water (step II-2) is preferable. As described above, it is preferable to supply alkylene glycol as an absorbent for water to the purification column (II-2) in step II-2. Component (E) contains a large amount of alkylene glycol. (E) Supplying it as an absorbent for water to step II-2 not only effectively utilizes the conventionally discarded mixture, but also surprisingly improves the purity of the cyclic formal.

The supply position of the component (D) distilled from the top of the purification column (III) can be any position in the step II, and can be supplied to the step of removing the formaldehyde derivative (step II-1), the step of removing the water ( In the cyclic formal mixture (A) supplied to the purification column in step II-2) or in step II-1. Among them, it is preferable to supply to the step of removing formaldehyde derivatives (step II-1) or to the cyclic formal mixture (A) supplied to the purification column in step II-1. As described above, it is preferable to supply water to the purification tower (II-1) in the step II-1, and the component (D) contains a large amount of water, and by supplying the component (D) to the purification tower (II-1) of the step II-1 In -1) or the cyclic formal mixture (A), not only the conventionally discarded mixture can be effectively utilized, but also the purity of the cyclic formal can be improved surprisingly.

When the component (D) is supplied to the purification column (II-1) in the step II-1, it is preferably supplied to the same number of stages as the supply stages of the cyclic formal mixture (A).

Component (D) contains formaldehyde, and its content is preferably 5000 ppm or less. More preferably, it is 3000 ppm or less, and still more preferably, it is 1000 ppm or less. The lower the content of formaldehyde in the component (D), the better, and it is particularly preferably 0 ppm. Alkylated cyclic formal compounds such as 2-methyl-1,3-dioxolane tend to be able to be produced with higher purity by adjusting the content of formaldehyde in component (D) to 5000 ppm or less Less cyclic formal compounds. The formaldehyde content of the component (D) can be controlled by supplying the above-mentioned alkylene glycol or adjusting the temperature and pressure of the purification column (III).

In the present invention, it is preferable to use a purification tower in both Step II (Step II-1, Step II-2) and Step III. The reflux ratio at the top of each purification tower is preferably 0.1-10, more preferably 0.5-8, even more preferably 0.5-5.

In the conventional production method of cyclic formal, the treatment of the mixture containing alkylene glycol obtained in the purification step (step II) of the cyclic formal mixture has not been explained, and it has been discarded substantially. In the present invention, by effectively utilizing the mixture containing the above-mentioned alkylene glycol, the surprising effects of reducing waste and improving the purity of cyclic formal can be obtained. The high-purity cyclic formal obtained in this way satisfies the requirements in the field (polyacetal resin, etc.) where it is used as a raw material, and is highly useful industrially.

Example

Hereinafter, the production method of the cyclic formal of the present invention will be described in detail by way of examples (production method of 1,3-dioxolane), but the present invention is not limited to the production methods of these examples.

(a) Composition analysis method

In the compositional analysis of each mixture, quantification was carried out under the following conditions using a gas chromatograph (model: GC-14A) manufactured by Shimadzu Corporation.

1. Analysis method: gas chromatography

2. Model: GC-14A

3. Detector: TCD

4. Chromatographic column: Porapak T

(b) Equipment for producing cyclic formal

The production apparatus of the cyclic formal used in the Example and the comparative example is shown in FIG.1, FIG.2, FIG.3 and FIG.4. It should be noted that each figure only shows main equipment, and auxiliary equipment is omitted.

[Example 1]

Ethylene glycol and formaldehyde are reacted in the presence of an acid catalyst to obtain a mixture (A) containing 1,3-dioxolane. Sulfuric acid was used as acid catalyst.

An apparatus for producing a cyclic formal compound is shown in FIG. 1 .

(Process Ⅱ-1)

The mixture (A) having the composition shown in Table 1 is supplied to the purification column (II-1), and the mixture (D) distilled from the top of the purification column (III) is supplied to the purification column (II-1) . Furthermore, water was supplied to the purification column (II-1) at a rate of 260 g/hour from a supply line different from the supply lines of the mixture (A) and the mixture (D). The temperature and pressure of the purification column (II-1) were 100°C at the bottom of the column, 25kPa at the pressure, and 75°C at the top of the column. The reflux ratio at the top of the purification column (II-1) was adjusted to 2. Table 1 shows the composition of the mixture (B) distilled from the top of the purification column (II-1). Separately, the mixture (G) was taken out from the bottom of the purification column (II-1).

(Process Ⅱ-2)

Then, the mixture (B) distilled from the top of the purification column (II-1) is supplied to the purification column (II-2), and 1,3-dioxolane and water are separated. The purification conditions of the purification column (II-2) were: the temperature at the bottom of the column was 170°C, the pressure was 30 kPa, and the temperature at the top of the column was 75°C. The reflux ratio at the top of the purification column (II-2) was set to 4. 1,3-dioxolane was distilled off from the top of the purification column (II-2).

(Process Ⅲ)

Ethylene glycol was supplied at 7 g/H to the mixture (C) distilled from the bottom of the purification column (II-2), and supplied to the fifth stage from the upper stage of the purification column (III).

The operating conditions of the purification tower (Ⅲ) are: the temperature at the bottom of the tower is 200°C, the pressure is 15kPa, and the temperature at the top of the tower is 99°C. Set the reflux ratio at the top of the column to 1. The mixture (D) distilled from the top of the purification column (III) contains 1,3-dioxolane, formaldehyde and water. The mixture (E) distilled off from the bottom of the purification column (III) contains ethylene glycol, 1,3-dioxolane and water. The mixture (D) is fed to the seventh stage from the upper stage of the supply stage of the purification column (II-1). Separately, the mixture (E) is supplied to a purification column (II-2). Table 1 shows the composition of each of the above mixtures and the amount supplied to the distillation column.

Table 1

weight% Mixture (A) Mixture (B) Mixture (C) Mixture (D) Mixture (E) Mixture (F) Mixture (G) 1,3-dioxolane 76.31 78.16 2.80 24.58 1.53 99.98 6.17 Formaldehyde 0.61 0.05 0.01 0.20 0.00 0.00 0.44 water 23.07 21.79 4.70 75.22 0.64 0.00 93.93 Ethylene glycol 0.00 0.00 92.49 0.00 97.83 0.00 0.00 2-Methyl-1,3-dioxolane 0.00 0.00 0.00 0.00 0.00 0.02 0.00 Supply (g/H) 208.3 198.0 919.0 49.9 868.9 129.0 268.4

[Example 2]

The same operation as in Example 1 was performed except that the temperature of the bottom of the purification column (III) was set to 190°C. The results are shown in Table 2.

Table 2

weight% Mixture (A) Mixture (B) Mixture (C) Mixture (D) Mixture (E) Mixture (F) Mixture (G) 1,3-dioxolane 76.31 78.16 2.8 24.93 1.53 99.98 6.17 formaldehyde 0.61 0.05 001 0.3 0.01 0 0.44 water 23.07 21.79 4.7 74.77 0.73 0 93.39 Ethylene glycol 0.00 0 92.49 0 97.93 0 0 2-Methyl-1,3-dioxolane 0.00 0 0 0 0 0.02 0 Supply (g/H) 208.3 198.0 919.0 49.2 869.7 129.0 267.7

[Example 3]

The same operation as in Example 1 was performed except that the temperature of the bottom of the purification column (III) was set to 210°C. The results are shown in Table 3.

table 3

weight% Mixture (A) mixture (B) mixture (C) mixture (D) Mixture (E) Mixture (F) Mixture (G) 1,3-dioxolane 76.31 78.16 2.8 23.95 1.55 99.98 6.12 formaldehyde 0.61 0.05 0.01 0.2 0 0 0.44 water 23.07 21.79 4.7 75.68 0.5 0 93.44 Ethylene glycol 0.00 0 92.49 0 97.95 O 0 2-Methyl-1,3-dioxolane 0.00 0 0 0 0 0.02 0 Supply (g/H) 208.3 198.0 919.0 51.2 867.7 129.0 269.7

[Example 4]

The production apparatus of cyclic formal is shown in FIG. 2 . The same operation as in Example 1 was performed except that the mixture (D) distilled from the top of the purification column (III) was supplied to the mixture (A) and then to the purification column (II-1). The results are shown in Table 4.

Table 4

weight% Mixture (A) mixture (B) mixture (C) mixture (D) Mixture (E) Mixture (F) Mixture (G) 1,3-dioxolane 76.31 78.35 2.80 24.58 1.52 99.98 5.52 formaldehyde 0.61 0.05 0.01 O.20 0.00 0.00 0.48 water 23.07 21.60 4.70 75.22 0.64 0.00 94.00 Ethylene glycol 0.00 0.00 92.49 0.00 97.83 0.00 0.00 2-Methyl-1,3-dioxolane 0.00 0.00 0.00 0.00 0.00 0.02 0.00 Supply (g/H) 208.3 199.7 919.O 49.9 868.9 130.8 266.7

[Example 5]

The production apparatus of cyclic formal is shown in FIG. 3 . The same operation as in Example 1 was performed except that the mixture (D) distilled from the top of the purification column (III) was supplied to the purification column (II-2). The results are shown in Table 5.

table 5

weight% Mixture (A) mixture (B) mixture (C) mixture (D) Mixture (E) Mixture (F) Mixture (G) 1,3-dioxolane 76.31 78.16 2.69 24.55 1.53 99.97 2.34 formaldehyde 0.61 0.05 0.03 0.30 0.06 0.00 0.65 water 23.07 21.79 8.43 75.15 0.64 0.00 97.01 Ethylene glycol 0.00 0.00 88.85 0.00 97.77 0.00 0.00 2-Methyl-1,3-dioxolane 0.00 0.00 0.00 0.00 0.00 0.03 0.00 Supply (g.H) 208.3 198.0 956.7 50.0 869.4 129.4 181.1

[Comparative example 1]

The production apparatus of cyclic formal is shown in FIG. 4 . Except that the purification column (III) of the alkylene glycol mixture is not provided and 266.5 g/H of ethylene alcohol equivalent to the mixture (C) is directly supplied to the purification column (II-2), the same procedure as in Example 1 is carried out. Same operation. The results are shown in Table 6.

Table 6

weight% Mixture (A) Mixture (B) Mixture (C) Mixture (F) Mixture (G) 1,3-dioxolane 76.31 77.57 9.65 99.03 2.60 Formaldehyde 0.61 0.05 0.04 0.16 0.54 water 23.07 23.38 16.20 0.80 96.86 Ethylene glycol 0.00 0.00 74.11 0.00 0.00 2-Methyl-1,3-dioxolane 0.00 0.00 0.00 0.02 0.00 Supply (g/H) 208.3 197.5 266.5 128.8 220.1

[Comparative example 2]

An apparatus for producing a cyclic formal compound is shown in FIG. 4 . The same operation as in Comparative Example 1 was carried out except that the purification column (III) of the alkylene glycol mixture was not provided, and 840 g/H of ethylene glycol was directly supplied to the purification column (II-2). The results are shown in Table 7.

Table 7

weight% Mixture (A) Mixture (B) Mixture (C) Mixture (F) Mixture (G) 1,3-dioxolane 76.31 77.57 2.80 99.98 2.60 formaldehyde 0.61 0.05 0.01 0.00 0.54 water 23.07 22.38 4.70 0.00 96.86 Ethylene glycol 0.00 0.00 92.49 0.00 0.00 2-Methyl-1,3-dioxolane 0.00 0.00 0.00 0.02 0.00 Supply (g/H) 208.3 197.5 919.0 127.5 220.0

As shown in the comparative example, in the conventional method for producing cyclic formal, there was a problem that the component distilled from the bottom of the purification column (II-2) (mixture (C)) was discarded. In addition, in order to improve the yield In order to obtain the purity of the cyclic formal, a large amount of ethylene glycol needs to be supplied to the purification column (II-2), and since this ethylene glycol is contained in the mixture (C), there is a problem that the amount of waste increases.

The production method of the present invention is a method of reusing the mixture (C) distilled from the bottom of the purification column (II-2). By this method, the amount of ethylene glycol to be supplied can be greatly reduced. In addition, in It is excellent in that the amount of waste can be significantly reduced, and it is an excellent method capable of obtaining high-purity cyclic formal.

Claims (7)

1. the manufacture method of a cyclic formals, comprise and aklylene glycol and formaldehyde derivatives are reacted in the presence of acid catalyst and obtain the operation of cyclic formals mixture and the operation of this cyclic formals mixture being carried out purifying, described manufacture method is characterised in that

Also possess following operation:

To carry out purifying to the mixture that contains aklylene glycol that this cyclic formals mixture carries out obtaining in the operation of purifying and be supplied to this cyclic formals mixture is carried out in the operation of purifying.

2. the manufacture method of cyclic formals as claimed in claim 1 is characterized in that, the operation that this cyclic formals mixture is carried out purifying comprises the operation of removing formaldehyde derivatives and removes the operation of anhydrating.

3. the manufacture method of cyclic formals as claimed in claim 1, it is characterized in that, carry out in the operation of purifying at the mixture that this is contained aklylene glycol, the composition that will distillate from the cat head of purification column and the composition that distillates at the bottom of the tower of purification column are supplied to respectively this cyclic formals mixture are carried out the operation of purifying.

4. the manufacture method of cyclic formals as claimed in claim 2, it is characterized in that, carry out in the operation of purifying at the mixture that this is contained aklylene glycol, the composition that will distillate from the cat head of purification column is supplied to from this cyclic formals mixture to be removed in the operation of formaldehyde derivatives, and the composition that will distillate at the bottom of the tower of purification column is supplied to this except the operation of anhydrating.

5. the manufacture method of cyclic formals as claimed in claim 2, it is characterized in that, carry out in the operation of purifying at the mixture that this is contained aklylene glycol, the composition that will distillate from the cat head of purification column is supplied to this cyclic formals mixture, and the composition that will distillate at the bottom of the tower of purification column is supplied to this except the operation of anhydrating.

6. such as the manufacture method of each described cyclic formals in the claim 1 ~ 5, it is characterized in that, ethylene glycol is supplied in this mixture that contains aklylene glycol or to this mixture that contains aklylene glycol carries out in the operation of purifying.

7. the manufacture method of cyclic formals as claimed in claim 1 is characterized in that, carries out in the operation of purifying at the mixture that this is contained aklylene glycol, and the temperature at the bottom of the tower of purification column is 190 ℃ ~ 210 ℃.

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