KR101422850B1 - Process for producing 1-methoxy-2-propanol - Google Patents

Abstract

Methoxy-2-propanol which exhibits a high conversion of propylene oxide and a high selectivity of 1-methoxy-2-propanol and which can reduce the content of by-products. 1-methoxy-2-propanol is produced through a reaction step in which methanol and propylene oxide are reacted at 90-110 占 폚 in the presence of a tertiary amine to obtain a reaction liquid and a distillation step in which the reaction liquid is distilled. In this method, methanol, propylene oxide and tertiary amine are continuously fed into a tower reactor having therein a temperature control unit composed of a helical tube through which a heat transfer medium can circulate, and the resulting reaction tank liquid is continuously supplied as a regular packing Methanol was distilled from the packed column to prepare 1-methoxy-2-propanol.

Propylene oxide, conversion, tertiary amine, distillation column, regulation packing, temperature control unit

Description

PROCESS FOR PRODUCING 1-METHOXY-2-PROPANOL < RTI ID = 0.0 >

The present invention relates to a process for producing 1-methoxy-2-propanol, and more particularly, to a process for producing 1-methoxy-2-propanol with a high conversion ratio of propylene oxide and a high selectivity.

As with other glycol ethers, 1-alkoxy-2-propanol is used in resin solvents for paints and inks as well as in dyeing couplers for brake oils, fabrics and leather products, and has marketability different from so-called general-purpose solvents It is useful industrial goods.

As a conventional method for producing 1-alkoxy-2-propanol, there is known a method of producing propylene oxide by reacting an alcohol with propylene oxide in the presence of a catalyst. As a by-product, 2-alkoxy-1-propanol and dipropylene glycol mono A compound having a high boiling point such as an alkyl ether is often produced. For example, when the alcohol is methanol, distillation may be carried out to separate the 1-methoxy-2-propanol and the by-product and reduce the content of the by-product. However, Ethoxy-1-propanol have a similar boiling point, making it difficult to completely separate them. For example, it is known that about 300 ppm of 2-methoxy-1-propanol is mixed in 1-methoxy-2-propanol used as an industrial product. It is known that 2-methoxy-1-propanol has strong toxicity (reproductive toxicity and the like), and it is an important task to reduce the content of 2-methoxy-1-propanol in an industrially used product as much as possible.

Japanese Unexamined Patent Publication (Kokai) No. 56-15229 (Patent Document 1) discloses a process for producing a propylene oxide which comprises reacting a lower monohydric alcohol with propylene oxide in the presence of a tertiary amine, adjusting the molar ratio of alcohol to propylene oxide to about 2 or more, To produce 1-alkoxy-2-propanol.

In this production process, 1-methoxy-2-propanol can be prepared by reacting methanol and propylene oxide in the presence of a tertiary amine. In this method, by separating 1-methoxy-2-propanol and a by-product (such as a compound having a high boiling point such as 2-methoxy-1-propanol) As described above, since 1-methoxy-2-propanol and 2-methoxy-1-propanol have similar boiling points, it is difficult to efficiently separate them by distillation. The efficiency of distillation can be improved by increasing the reflux ratio or increasing the height of the distillation column, but it is not practical because of high cost.

As a result, a convenient distillation operation is possible, and another approach is required in order to efficiently separate 1-methoxy-2-propanol and by-products. As another approach, for example, a method of improving the conversion ratio of propylene oxide and the selectivity of 1-methoxy-2-propanol to reduce the content of the by-product in advance and distillation is considered effective. Patent Literature 1 discloses that 1-methoxy-2-propanol is produced at a conversion of propylene oxide of 93.2 to 98.8% and a selectivity of 92.9 to 96.5% when methanol and propylene oxide are reacted at 80 ° C or lower and distillation Is described.

Japanese Patent Application Laid-Open No. 7-206744 (Patent Document 2) discloses a method for producing a glycol ether from alkylene oxide and an alcohol in which methanol and propylene oxide are reacted at 80 ° C and 100 ° C Methoxy-2-propanol can be produced at a conversion of propylene oxide of 97 to 100% and a selectivity of 94 to 95% when the reaction is carried out at 120 ° C. However, even with the method of this document, the selectivity is not sufficient.

As described above, since 1-methoxy-2-propanol is commonly used as an industrial article, and the 2-methoxy-1-propanol has a very strong toxicity, by-products (especially 2-methoxy- 1-propanol), in other words, it is necessary to remarkably improve the conversion of propylene oxide and the selectivity of 1-methoxy-2-propanol.

[Patent Document 1] Japanese Unexamined Patent Publication (Kokai) No. 56-15229 (Claims, Examples)

[Patent Document 2] Japanese Unexamined Patent Application Publication No. 7-206744 (Claims, Examples)

Accordingly, an object of the present invention is to provide a process for producing 1-methoxy-2-propanol with high conversion and high selectivity.

It is another object of the present invention to provide a process for producing 1-methoxy-2-propanol with reduced content of toxic by-products.

It is another object of the present invention to provide a method for efficiently producing 1-methoxy-2-propanol at low cost even on an industrial scale.

As a result of intensive studies to achieve the above object, the present inventors have found that when methanol and propylene oxide are reacted at a specific temperature and distillation, 1-methoxy-2-propanol can be selectively produced and the content of toxic by- Methoxy-2-propanol can be prepared, and the present invention has been completed.

That is, in the method of the present invention, a reaction step of reacting methanol and propylene oxide at 90 to 110 ° C in the presence of a tertiary amine to obtain a reaction liquid, and a distillation step of distilling the reaction liquid to obtain 1-methoxy- Propanol.

In this method, methanol and propylene oxide may be reacted so that the ratio of methanol to propylene oxide is about 2 to 10 times the molar amount. The tertiary amine may be used in a proportion of about 0.1 to 10% by weight based on the total amount of methanol, propylene oxide and tertiary amine.

In this method, a tower-type reactor may also be used. The tower-type reactor may have a temperature control unit therein, which is constituted by a helical tube capable of circulating the heat transfer medium. In the method of the present invention, methanol, propylene oxide, and tertiary amine may be continuously supplied to the reactor, and the reaction tank liquid from the reactor may be continuously distilled. In addition, a plurality of reactors may be disposed in series. In addition, the reaction tank liquid obtained in the reaction step may be distilled from a packed column filled with a structured packing.

In the present invention, since methanol and propylene oxide are reacted at a specific temperature in the presence of a tertiary amine, the conversion ratio of propylene oxide and the selectivity of 1-methoxy-2-propanol can be improved, 1-methoxy-2-propanol can be selectively prepared by reducing the content of the product. In addition, since it is possible to inhibit the formation of byproducts having a high boiling point (such as 2-methoxy-1-propanol and dipropylene glycol monomethyl ether), it is possible to efficiently produce 1-methoxy- - propanol and by-products can be separated. Therefore, even at an industrial scale, 1-methoxy-2-propanol can be efficiently produced at low cost.

In the present invention, a reaction step of reacting methanol and propylene oxide at a predetermined temperature in the presence of a tertiary amine to obtain a reaction liquid, and a distillation step of distilling the reaction liquid to produce 1-methoxy-2-propanol do.

[Reaction Process]

The reactor of the reaction process may be a commonly used reactor, for example, a tower, a molding, a tubular, or the like. It may also be a continuous reactor capable of continuous operation, or a batch reactor capable of batch operation (or semi-batch operation). It is also preferable that the reactor to be used is provided with a temperature control unit useful for alleviating the temperature change due to the reaction to maintain the desired reaction temperature. As the temperature control unit, for example, a unit (coil temperature control unit) which can circulate a heat transfer medium (for example, water, steam, oil, etc.) And a unit (jacket) capable of flowing the heat transfer medium between the heat exchanger and the reactor. In the present invention, it is preferable to use a tower reactor (reaction tower) in terms of temperature control efficiency and production efficiency. In particular, a tower reactor (reaction tower) having a temperature control unit (for example, a temperature control unit formed of a spiral tube through which a heat transfer medium can flow) may be used in the reactor.

The number of reactors is not particularly limited and may be 1, and a plurality of units (two or more units) may be combined to obtain a product with a high reaction yield. In terms of reaction efficiency, equipment, and energy cost, typically, the reactor has 2 to 3 groups (particularly, 2 groups). A plurality of reactors may be arranged in series (arranged), arranged in parallel, or arranged in combination of series and parallel. Typically, a plurality of reactors are disposed in series. When a plurality of reactors are used, it is preferable that at least one of the plurality of reactors (in particular, the first reactor to which the reaction component is supplied) is provided with a coil-shaped temperature control unit.

In addition, in order to improve the reaction efficiency (reaction yield), a tower reactor (reaction tower) filled with a packing as required may be used. Examples of the filler include ring-shaped fillers such as poling, lashing, and ringing, saddle-shaped fillers such as saddle and McMahon packing, ball-shaped fillers, fillers of other shapes such as sulzer packing, and the like. These fillers may be used alone or in combination of two or more. Preferred fillers are ring-shaped fillers (e. G., Rashihing et al.).

The ratio of methanol to propylene oxide is, for example, 2-fold mol or more (for example, 2 to 10-fold mol), preferably 3 to 9-fold mol, more preferably 4 8-fold molar amount (especially 5 to 7-fold molar amount). When the ratio of methanol to propylene oxide is small, the content of high boiling point byproducts such as higher-order addition products of propylene oxide (for example, dipropylene glycol monomethyl ether) may increase.

As the tertiary amine, typically tertiary aliphatic amines, tertiary aromatic amines, tertiary heterocyclic amines and the like can be exemplified. Examples of tertiary aliphatic amines, e.g., trimethylamine, triethylamine, tri -n- propyl amine such as a trialkylamine (in particular tree C _{1 - 6} alkyl amines), dimethyl ethyl amine, such as di-alkyl amines (especially di-C _{1 - 6} alkyl amines and the like), _{- 6} alkyl, C _1. Examples of tertiary aromatic amines, e.g., N, N- dimethylaniline, N, N- di-N- alkyl -N- alkyl anilines such as aniline acetate (especially, NC _{1 - 6} alkyl, -NC _{1 - 6} alkyl aniline) And the like. As the tertiary heterocyclic amine, for example, pyridine, picoline, quinoline and the like can be given. These tertiary amines can be used alone or in combination of two or more.

In the present invention, 1-methoxy-2, and to use a tertiary amine that has a lower boiling point than the boiling point of the preferred propanol, for example, trimethylamine, triethylamine, dimethyl ethyl amine, such as a tree C _{1 - 3} alkylamine, pyridine, and the like. A particularly preferred tertiary amine is triethylamine.

The proportion of the tertiary amine is 0.1 to 10% by weight, preferably 0.2 to 7% by weight, more preferably 0.5 to 5% by weight, particularly preferably 0.7 to 2% by weight based on the total amount of methanol, propylene oxide and tertiary amine % (For example, 0.8 to 1.5% by weight).

Methanol, propylene oxide and tertiary amine can be fed batchwise (or semi-batch) into the reactor, but are usually continuously fed in terms of industrial productivity. The feed rate of methanol, propylene oxide and tertiary amine to the reactor may be 2.0 to 5.0 m / h, preferably 2.1 to 4.6 m / h, more preferably 2.2 to 4.2 m / h, have.

In the process of the present invention, methanol and propylene oxide are reacted in the presence of a tertiary amine at 90 to 110 캜, preferably 95 to 110 캜, more preferably 95 to 105 캜. When the reaction is carried out at a temperature lower than the above temperature range, the conversion of propylene oxide tends to be lowered. On the other hand, when the reaction is carried out at a temperature higher than the above temperature range, the content of the by-products, 2-methoxy-1-propanol and dipropylene glycol monomethyl ether tends to increase.

In order to prepare 1-methoxy-2-propanol having a high conversion of propylene oxide and a reduced content of the by-product, it is preferable to maintain the reaction temperature at a specific temperature (90 to 110 ° C) And it is effective to control the reaction temperature (the temperature of the reaction system). The temperature control unit, particularly, the coiling-phase temperature control unit can be used for controlling the reaction temperature. For example, in the case of circulating the heat transfer medium in the coil-shaped temperature control unit (particularly, a temperature control unit constituted by a helical tube), the heat transfer efficiency can be improved, Can be controlled. Further, when the reaction material is continuously supplied to the reactor to perform the reaction, it is usually difficult to control and maintain the reaction temperature (the temperature of the reaction system) due to the variation of the composition of the reaction system and the temperature change due to the reaction. Even in such a case, the temperature can easily be controlled by flowing a heat transfer medium (particularly, water) in the coil-shaped temperature control unit (particularly, a temperature control unit formed of a helical tube) It becomes possible to maintain the temperature at a specific temperature. As the heat transfer medium, oil (silicone oil or the like) may be used, but water is usually used. The temperature of the medium (particularly, water) can be selected according to the reaction temperature, but is preferably lower than the reaction temperature. For example, the difference between the temperature of the medium and the desired reaction temperature may be about 5 to 30 占 폚, preferably 7 to 25 占 폚, and more preferably about 10 to 20 占 폚. If the difference between the temperature of the medium and the desired reaction temperature is too large, it may become difficult to maintain the temperature of the reaction system at a constant (almost constant) level.

Is defined as the sum of the vapor pressure determined from the pressure of the reaction system, the composition of the reactant and the reaction temperature, and the gas pressure of the inert gas (nitrogen gas or the like) which is pushed (or press- Cm 2 G (≒ 1.0 × 10 ⁵ to 20 × 10 ⁵ Pa), preferably 2 to 15 kg / cm 2 G (≒ 2.0 × 10 ⁵ to 15 × 10 ⁵ pa), and more preferably 3 to 10 Kg / cm < 2 > G (≒ 3.0 x 10 ⁵ to 10 x 10 ⁵ pa).

[Distilling process]

In the distillation step, the reaction liquid obtained through the reaction step is distilled.

The distillation apparatus (distillation apparatus) may be a commonly used distillation apparatus (distillation tower), for example, a tower (a perforated plate tower, a bubble tower, etc.), a packed tower, and the like. In the present invention, it is preferable to use a packed column in order to suppress pressure loss in the apparatus. The packing of the packed column may be a random packing, but it is preferable to use a structured packing in order to further suppress the pressure loss in the apparatus and further improve the efficiency of the distillation. The regular filler may be a general-purpose filler, for example, a metal such as titanium or zirconium or an alloy thereof, stainless steel (such as austenitic stainless steel), ceramics, or the like. In addition, the regular packing may be sheet-like (plate-like), mesh-like (network), grid-like (grid-like) or the like. These regular fillers may be used alone or in combination of two or more.

The distillation column has a number of stages (theoretical number of stages) of 30 or more stages (for example, 30 to 60 stages, preferably 32 to 55 stages, more preferably 30 stages or more) since the separation performance is improved by increasing the number Preferably about 35 to 50 stages) of the distillation column. The number of the distillation columns is not particularly limited and may be one or a plurality of (two or more) may be combined. In view of the reaction yield, equipment, energy cost, etc., (Particularly, the second group) can be used. In addition, in order to improve the distillation efficiency (separation efficiency), the distillation is preferably performed in multiple stages. Typically, distillation is carried out in two to three stages (particularly, two stages) in terms of recovery efficiency of the desired product. In each step, the number of distillation columns used may be the same or different. For example, two distillation columns may be used in the first stage, and one distillation column may be used after the second stage. In the present invention, for example, in the distillation operation at the first stage, a low boiling point component (unreacted methanol, tertiary amine, etc.) is distilled out, and in the distillation operation at the second stage, the high boiling point component (2-methoxy- 1-propanol, dipropylene glycol monomethyl ether, and the like) can also be removed. Further, the methanol and the tertiary amine flowing out in the first stage of the distillation operation may be reused as the reactant again.

The reaction step and the distillation step may be carried out separately, but it is advantageous to carry out the two steps continuously in view of industrial productivity. When the reaction step and the distillation step are continuously carried out, the conversion of propylene oxide is 99 mol% or more (for example, 99.1 to 99.9 mol%, preferably 99.2 to 99.8 mol%, more preferably 99.3 to 99.7 mol% , Particularly about 99.4 to 99.6 mol%) of 1-methoxy-2-propanol. The selectivity (based on propylene oxide) of 1-methoxy-2-propanol is 99.9 mol% or more (for example, 99.910 to 99.999 mol%, preferably 99.930 to 99.995 mol%, more preferably 99.9 to 50 mol% 99.992 mol%, especially about 99.960 to 99.99 mol%). The selectivity (based on propylene oxide) of 2-methoxy-1-propanol is about 0.001 to 0.03 mol% (for example, 0.002 to 0.028 mol%, particularly 0.003 to 0.026 mol%). By the method of the present invention, 1-methoxy-2-propanol having a very reduced content of 2-methoxy-1-propanol having a strong toxicity can be produced.

[Example]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

In the examples and comparative examples, reactants, reactors and distillation apparatuses having the following compositions were used.

Reactant; Methanol: 3462 kg / h (108.1 kmol / h)

           Propylene oxide: 1046 kg / h (18.0 kmol / h)

           Triethylamine: 45.5 kg / h (0.45 kmol / h)

           [Methanol / propylene oxide (molar ratio) = 6, concentration of triethylamine = 1.0% by weight]

Reactor 1; (Manufactured by Mitsui Josen Corporation, inner diameter: 1450 mmφ, height: 14698 mm)

Reactor 2; (Manufactured by Mitsui Josen Corporation, inner diameter: 500 mm, height: 15708 mm)

Distillation tower 1; (Inner diameter 1100 mmφ, height 30948 mm, theoretical number 45 manufactured by Mitsui Josen Corporation) filled with a regulating filler (Sumitomo SFLOW 250MY, manufactured by Sumitomo Plant Engineering Co., Ltd.)

Distillation column 2; (Manufactured by Mitsui Josen Corporation, inner diameter 1100 mmφ, height 30948 mm, yarn number 60, theoretical number 36).

In Examples and Comparative Examples, conversion of propylene oxide and selectivity of each component were determined by the following methods.

[Conversion rate]

The conversion of propylene oxide was determined by gas chromatography analysis of the reaction product, and the content of propylene oxide in the reaction solution was measured and found as a ratio of the content of propylene oxide before the reaction. That is, when the content (mol number) of the propylene oxide before the reaction is represented by C and the content (number of moles) of propylene oxide in the reaction liquid is represented by C ', the conversion ratio (mol%) = (1- (C' / C) .

[Selectivity of each component]

The selectivity of each component, for example, the selectivity of 1-methoxy-2-propanol, can be determined by analyzing the reaction product by gas chromatography, measuring the content of 1-methoxy-2-propanol in the reaction solution, Of the total amount. That is, when the content (mol number) of 1-methoxy-2-propanol in the reaction liquid is S and the total amount (total mol number) of reaction products is S ', the selectivity (mol%) = (S / S' Is displayed. Further, other components are obtained in the same manner.

[Example 1]

The reaction material was continuously supplied to a reactor 1 having a temperature control unit composed of a helical tube through which a heat transfer medium could flow and the reactor 1 was passed through the reactor 2 to carry out the reaction. In the reactor 1, water was passed through the unit at 80 ° C, and the temperature of the reaction system was controlled at 97 ° C to conduct the reaction. In the reaction tank liquid obtained, the conversion of propylene oxide was 99.6 mol%. The selectivity (based on propylene oxide) of 1-methoxy-2-propanol, 2-methoxy-1-propanol, dipropylene glycol monomethyl ether and other components was 87.7 mol%, 6.3 mol% 2.3 mol% and 3.7 mol%, respectively. Subsequently, the reaction tank liquid was distilled using the distillation column 1 under the conditions of a reflux ratio of 3.2 and an outlet rate of 86.5%. The conversion of propylene oxide and the selectivity of each component (based on propylene oxide) were determined in the purified liquid obtained by distillation.

[Example 2]

The procedure of Example 1 was repeated except that the distillation column 1 was used instead of the distillation column 1, and the conversion of propylene oxide and the selectivity of each component (based on propylene oxide) were determined in the obtained purified liquid.

[Comparative Example 1]

The reaction was carried out in the same manner as in Example 1 except that the temperature of the reaction system was not controlled. The obtained reaction tank liquid was distilled using a distillation column 2. The conversion of propylene oxide and the selectivity of each component (based on propylene oxide) were determined in the purified liquid obtained by distillation.

[Comparative Example 2]

The reaction material was reacted in the same manner as in Example 1. In the obtained reaction tank liquid, the conversion of propylene oxide and the selectivity of each component (based on propylene oxide) were determined.

[Comparative Example 3]

The reaction was carried out in the same manner as in Example 1 except that the temperature of the reaction system was not controlled. In the obtained reaction tank liquid, the conversion of propylene oxide and the selectivity of each component (based on propylene oxide) were determined.

The results of Examples and Comparative Examples are shown in Table 1. 1-MMPG "," 2-MMPG "," high boiling point component "and" other "refer to 1-methoxy-2-propanol, 2-methoxy-1-propanol, dipropylene glycol monomethyl ether, and other components (based on propylene oxide).

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Reaction temperature (캜) 97 97 135 97 135 Conversion rate (mol%) 99.6 99.6 99.4 99.6 99.4 1-MMPG (mol%) 99.991 99.968 99.949 87.7 85.6 2-MMPG (mol%) 0.003 0.026 0.038 6.3 8.5 High boiling point component (mol%) 0.006 0.006 0.005 2.3 2.5 Others (mol%) <0.0001 <0.0001 0.009 3.7 3.4

As apparent from Table 1, when the reaction product was reacted at a specific temperature range and distilled, the conversion of propylene oxide and the selectivity of 1-methoxy-2-propanol were very high, and the content of by- 1-methoxy-2-propanol reduced in content than the content of by-products contained in 1-methoxy-propanol which is commonly used. Further, in the distillation step, when the packed column filled with the regular packing as the distillation column was used, the effect became more remarkable.

In the method of the present invention, since 1-methoxy-2-propanol reduced in the content of by-products having strong toxicity even on an industrial scale can be produced, the obtained 1-methoxy- , Resin solvents for paints and inks as well as industrial products such as brake oils, dyeing couplers for fabrics and leather products, and the like.

Claims (5)

Methoxy-2-propanol is produced through a reaction step of reacting methanol and propylene oxide at 90 to 110 DEG C in the presence of a tertiary amine to obtain a reaction tank liquid and a distillation step of distilling the reaction tank liquid , And a spiral-shaped tube capable of circulating the heat transfer medium, and in which a plurality of column-shaped reactors filled with a packing and arranged in series are continuously provided with methanol, propylene oxide and tertiary amine And the reaction tank liquid from the reactor is continuously distilled in a packed column filled with a structured packing, thereby producing 1-methoxy-2-propanol. The method according to claim 1, wherein each of the plurality of tower reactors is a reactor having a spiral tube for allowing water to flow therethrough and filled with a ring-shaped filler. The method according to claim 1 or 2, wherein water having a temperature lower by 5 to 30 ° C than the reaction temperature is passed through a spiral tube to react. 3. A process according to claim 1 or 2 wherein two to three reactors are arranged in series. delete