Method for producing 2-methylene-1,3-propanediol diacetate and method for producing modified ethylene-vinyl ester copolymer

Abstract

To provide a method for producing MPDAc which can efficiently obtain 2-methylene-1,3-propanediol diacetate (MPDAc) of high purity at a high yield.SOLUTION: A method for producing MPADc (Z) using 2-methylene-1,3-propanediol (X: MPDA) as a raw material at a yield of 95% or more includes a first step of performing an esterification reaction of the MPDA (X) using an acetic acid (W) in the presence of a titanium-containing catalyst at a reaction temperature of 130°C or higher and 180°C or lower so that a molar ratio (W / (X+Y+Z)) of an acetic acid (W) to the total amount of the MPDA (X), 2-methylene-1,3-propanediol monoacetate (Y) and MPDAc (Z) in a reaction system is kept in a range of 0.01 or more and 1.95 or less while adding an acetic acid (Z) into the system and removing produced water to the outside of the system.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing 2-methylene-1,3-propanediol diacetate and a method for producing a modified ethylene-vinyl ester copolymer. [Background technology]

[0002] 2-Methylene-1,3-propanediol diacetate (hereinafter also referred to as "MPDAc") is used, for example, as a modifier (comonomer) for ethylene-vinyl alcohol copolymer (hereinafter also referred to as "EVOH") (see Patent Document 1). MPDAc-modified EVOH obtained by saponifying a copolymer of ethylene, vinyl ester, and MPDAc has the characteristics of having improved stretchability and shrinkability while maintaining good barrier properties compared to unmodified EVOH.

[0003] As a method for synthesizing MPDAc, Non-Patent Document 1 describes a method in which 2-methylene-1,3-propanediol (hereinafter also referred to as "MPDA") is reacted with acetic anhydride. Non-Patent Document 2 describes a method in which 3-chloro-2-(chloromethyl)-1-propene is reacted with sodium acetate.

[0004] Furthermore, Patent Document 2 describes a method for synthesizing an unsaturated ester by an ester exchange reaction of an unsaturated alcohol, in which 2-isopropenyl-5-methyl-4-hexen-1-ol and an alkyl senecioate are used as raw materials, and an ester exchange reaction is carried out while removing the by-product alcohol to synthesize 2-isopropenyl-5-methyl-4-hexen-1-yl-3-methyl-2-butenoate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-34647 A [Patent Document 2] JP 2016-108334 A [Non-patent literature]

[0006] [Non-Patent Document 1] CHIssidorides and AIMatar, "Pentaerythritol Derivatives.I. The Preparation of Pentaerythritol Monomethyl Ether" Journal of the American Chemical Society, 1955, 77, 23, p6382-6383 [Non-Patent Document 2] Fumio Sanda et al., "Radical polymerization of 3,9-dimethylene-1,5,7,11-tetraoxaspiro[5.5]undecane. Study of the structure of the polymer and mechanism of polymerization", Macromolecules, 1993, 26, 4, p729-736 Summary of the Invention [Problem to be solved by the invention]

[0007] When carrying out the esterification reaction using acetic anhydride as described in Non-Patent Document 1, the by-production of acetic acid by the reaction is problematic. In other words, it is necessary to neutralize the by-product with an amount of base corresponding to the amount of acetic acid, and in this case, a part of MPDAc dissolves in the aqueous phase, making it difficult to obtain MPDAc in high yield. Specifically, Non-Patent Document 1 obtains MPDAc in about 90% yield.

[0008] In the method of using 3-chloro-2-(chloromethyl)-1-propene as a raw material as described in Non-Patent Document 2, it is difficult to completely remove trace amounts of chlorine compounds contained in the raw material, and therefore, the obtained MPDAc may contain trace amounts of chlorine compounds, which is not industrially preferable.

[0009] In addition, when the method using the transesterification reaction of Patent Document 2 is applied to the synthesis of MPDAc, since the boiling point of the acetate ester is relatively low, the reaction temperature cannot be increased, and it is difficult to synthesize MPDAc efficiently and in a high yield. It is also possible to use an ester of a higher alcohol with a high boiling point and acetate. However, this is not desirable because it is costly and the by-product higher alcohol becomes waste.

[0010] When producing MPDAc industrially, it is desirable to produce MPDAc with a yield of 95% or more from the viewpoint of productivity, etc. However, it is difficult to efficiently produce high-purity MPDAc with such a high yield using the conventional synthesis methods described above. Therefore, the inventors have considered synthesizing MPDAc by an esterification reaction of MPDA and acetic acid. However, due to the low boiling point of acetic acid, it is difficult to increase the reaction temperature, as in the case of using the above-mentioned acetate ester, and it is difficult to efficiently synthesize MPDAc with a high yield.

[0011] The present invention has been made under the above circumstances, and an object of the present invention is to provide a method for producing 2-methylene-1,3-propanediol diacetate, which can efficiently produce 2-methylene-1,3-propanediol diacetate with high purity and in high yield, and a method for producing a modified ethylene-vinyl ester copolymer using the method for producing 2-methylene-1,3-propanediol diacetate. [Means for solving the problem]

[0012] The above objectives are: [1] A method for producing 2-methylene-1,3-propanediol diacetate (Z) from 2-methylene-1,3-propanediol (X) as a raw material in a yield of 95% or more, comprising a first step of carrying out an esterification reaction of 2-methylene-1,3-propanediol (X) using acetic acid (W) in the presence of a titanium-containing catalyst at a reaction temperature of 130° C. to 180° C. while adding acetic acid (Z) to the system so that the molar ratio (W / (X+Y+Z)) of acetic acid (W) to the total amount of 2-methylene-1,3-propanediol (X), 2-methylene-1,3-propanediol monoacetate (Y), and methylene-1,3-propanediol diacetate (Z) in the reaction system is maintained in the range of 0.010 to 1.95, and while removing water generated at the same time from the system; [2] The method for producing 2-methylene-1,3-propanediol diacetate according to [1], further comprising a second step of carrying out an esterification reaction of 2-methylene-1,3-propanediol (X) using acetic anhydride following the first step; [3] The method for producing 2-methylene-1,3-propanediol diacetate according to [1] or [2], wherein at least a part of the acetic acid (W) removed together with water from the system in the first step is reused for the esterification reaction in the first step; [4] A method for producing 2-methylene-1,3-propanediol diacetate according to any one of [1] to [3], further comprising a third step of purifying the resulting product liquid containing 2-methylene-1,3-propane diacetate (Z) so that the purity is 95% by mass or more; [5] A method for producing a modified ethylene-vinyl ester copolymer, comprising a step of copolymerizing 2-methylene-1,3-propanediol diacetate obtained by the method for producing 2-methylene-1,3-propanediol diacetate according to any one of [1] to [4], ethylene, and a vinyl ester, and a step of saponifying the copolymer obtained; This is achieved by providing Effect of the Invention

[0013] According to the present invention, there are provided a method for producing 2-methylene-1,3-propanediol diacetate, which can efficiently produce 2-methylene-1,3-propanediol diacetate with high purity and in high yield, and a method for producing a modified ethylene-vinyl ester copolymer using the method for producing 2-methylene-1,3-propanediol diacetate. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a graph showing the relationship between the MPDA concentration and the boiling point (reflux temperature) in a mixed solution of MPDA and acetic acid or water. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <Method for producing 2-methylene-1,3-propanediol diacetate> The method for producing 2-methylene-1,3-propanediol diacetate (MPDAc) of the present invention is a method for producing MPDAc (Z) in a yield of 95% or more using 2-methylene-1,3-propanediol (MPDA:X) as a raw material, and includes a first step of carrying out an esterification reaction of MPDA (X) using acetic acid (W) in the presence of a titanium-containing catalyst at a reaction temperature of 130° C. to 180° C. while adding acetic acid (Z) to the system so that the molar ratio (W / (X+Y+Z)) of acetic acid (W) to the total amount of MPDA (X), 2-methylene-1,3-propanediol monoacetate (hereinafter also referred to as "MPMAc") (Y) and MPDAc (Z) in the reaction system is maintained in the range of 0.010 to 1.95, and while removing water generated at the same time from the system. Note that MPMAc (Y) and MPDAc (Z) are produced in conjunction with the esterification reaction of MPDA (X). MPMAc(Y) is a so-called intermediate product, and MPDAc(Z) in the reaction system can reversibly become MPMAc(Y). The reaction scheme of the esterification reaction in the first step is as follows.

[0016] [ka]

[0017] In the above scheme, Ac represents an acetyl group (CH 3 -CO-).

[0018] In the method for producing MPDAc, a titanium-containing catalyst is used as a catalyst, so that decomposition of the raw material MPDA (X) and the like does not easily occur. On the other hand, when an acid catalyst such as sulfuric acid or paratoluenesulfonic acid is used as a catalyst, it is difficult to obtain MPDAc (Z) in high yield due to partial decomposition of MPDA (X) and the like. In addition, in the first step of the method for producing MPDAc, acetic acid (W) is used as a component for esterification, so that acetic acid is not by-produced, unlike when acetic anhydride is used. Therefore, in the method for producing MPDAc, the outflow of a part of the target product during neutralization treatment and the like is suppressed, and MPDAc (Z) can be obtained efficiently in high yield.

[0019] In addition, when a large amount of acetic acid (W) is charged from the beginning in order to increase the yield, the reaction temperature cannot be increased due to the low boiling point of acetic acid (W) (boiling point at 1 atmospheric pressure: 118°C). In contrast, in the method for producing MPDAc, the esterification reaction is carried out while maintaining the content of acetic acid (W) in the reaction system (reaction liquid) in a small range, so the reaction temperature can be relatively high. FIG. 1 is a graph showing the boiling points (reflux temperatures) of a mixture of MPDA and acetic acid and a mixture of MPDA and water. It can be seen that the higher the concentration of MPDA, in other words, the lower the concentration of acetic acid, etc., the higher the reflux temperature (reaction temperature) at which the reaction can be carried out. On the other hand, when the reaction temperature exceeds 180°C, a side reaction such as polymerization of MPDAc (Z) occurs. Thus, in the method for producing MPDAc, the content of acetic acid (W) in the reaction system is controlled and the esterification reaction is carried out in a relatively high reaction temperature range, so that MPDAc (Z) can be efficiently obtained with high purity and high yield.

[0020] Furthermore, in the production method of MPDAc, since a compound not containing chlorine is used as a raw material, there is also an advantage that the obtained MPDAc(Z) does not substantially contain chlorine compounds.

[0021] The method for producing MPDAc of the present invention will be specifically described below.

[0022] (first step) The method for producing MPDAc includes a first step (esterification reaction step) of obtaining MPDAc (Z) by esterification reaction of MPDA (X) and acetic acid (W) in the presence of a titanium-containing catalyst. This esterification reaction is carried out while removing by-produced water from the reaction system, that is, while removing water from a reaction liquid containing MPDA (X), acetic acid (W), MPMAc (Y), MPDAc (Z), etc. Usually, this esterification reaction is carried out in a state where the reaction liquid is boiling (azeotropic), and water is removed from the system by fractional distillation. During this fractional distillation, usually, a part of acetic acid (W), which has a boiling point relatively close to that of water, is also distilled. In addition, MPDA (X), MPMAc (Y), and MPDAc (Z), which have high boiling points, basically remain in the reaction system (reaction liquid). This esterification reaction is preferably carried out while refluxing at least a part of acetic acid (W), and at this time, a part of water may also be refluxed. The esterification reaction can be suitably carried out under an inert gas atmosphere such as a nitrogen atmosphere.

[0023] (Titanium-containing catalyst) Examples of titanium-containing catalysts (titanium-based catalysts) include titanium tetrachloride, titanium tetrabromide, tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, and titanium (IV) oxide. Among these, titanium alkoxides such as tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, and tetrabutoxytitanium are preferred. One or more types of titanium-containing catalysts can be used.

[0024] The amount of the titanium-containing catalyst used in the esterification reaction is preferably 0.0005 mol or more and 0.5 mol or less, more preferably 0.001 mol or more and 0.1 mol or less, and even more preferably 0.003 mol or more and 0.04 mol or less, relative to 1.00 mol of MPDA (X).

[0025] (Reaction conditions, etc.) The first step (esterification reaction) is carried out while adding acetic acid (W) to the reaction system so that the molar ratio (W / (X+Y+Z)) of acetic acid (W) to the total amount of MPDA (X), MPMAc (Y), and MPDAc (Z) in the reaction system is maintained in the range of 0.010 to 1.95. This esterification reaction is carried out while removing by-produced water from the reaction system. The content of each component in the reaction system may be the content of each component in the reaction liquid.

[0026] When the raw materials are charged, a reaction solution is prepared by mixing MPDA (X) and acetic acid (W) so that the molar ratio (W / X) of acetic acid (W) to MPDA (X) is 0.010 or more and 1.95 or less. Then, as the esterification reaction proceeds, acetic acid (W) is consumed, and some of the acetic acid (W) is distilled together with water, so that the amount of acetic acid (W) in the reaction system (reaction solution) decreases. Therefore, the esterification reaction is carried out while adding acetic acid (W) to the reaction system, i.e., while adding it to the reaction solution, so that the molar ratio (W / (X+Y+Z)) in the reaction system (reaction solution) does not deviate from the range of 0.010 or more and 1.95 or less. The addition of acetic acid (W) may be performed sequentially or continuously. In addition, acetic acid (W) may be added while constantly monitoring the content of each component in the reaction system (reaction solution), or acetic acid (W) may be added at an appropriate timing and amount based on data on the content of each component once obtained. In addition, the molar ratio (W / (X+Y+Z)) can be estimated from the temperature of the refluxing reaction solution. Therefore, acetic acid (W) may be added appropriately while monitoring the temperature change of the reaction solution.

[0027] The lower limit of the molar ratio (W / (X+Y+Z)) in the first step is 0.010, and 0.015, 0.02, or 0.03 may be preferred. If the molar ratio (W / (X+Y+Z)) in the first step is below the lower limit, the reaction does not proceed sufficiently, and MPDAc(Z) cannot be obtained efficiently and in high yield. The upper limit of the molar ratio (W / (X+Y+Z)) in the first step is 1.95, and preferably 1.50, 1.00, or 0.95. If the molar ratio (W / (X+Y+Z)) in the first step exceeds the upper limit, it becomes difficult to sufficiently increase the reaction temperature, and MPDAc with high purity cannot be obtained efficiently and in high yield. In addition, if the molar ratio (W / (X+Y+Z)) in the first step exceeds the upper limit, the total mass of the raw materials increases, which is undesirable in terms of productivity, environmental load, and the like. In the first step, the molar ratio (W / (X+Y+Z)) does not have to be constant all the time as long as it is maintained within a predetermined range.

[0028] The lower limit of the reaction temperature in the first step is 130°C, preferably 135°C, more preferably 140°C, and even more preferably 145°C. By setting the reaction temperature to the above lower limit or higher, MPDAc(Z) can be obtained efficiently in a short period of time with high purity and high yield. On the other hand, the upper limit of the reaction temperature is 180°C, and may be 170°C or 160°C. By setting the reaction temperature to the above upper limit or lower, polymerization of MPDAc(Z) can be suppressed and the yield can be increased. The reaction temperature may be constant, or may not be constant, for example, by gradually increasing the temperature. The reaction temperature in the esterification reaction is the temperature of the reaction liquid.

[0029] The lower limit of the reaction time in the first step is preferably 12 hours, and in some cases more preferably 20 hours, from the viewpoint of increasing the yield, etc. The upper limit of the reaction time is preferably 48 hours, and more preferably 40 hours, 30 hours, or 26 hours, from the viewpoints of efficiency, productivity, etc.

[0030] The first step (esterification reaction) can be carried out without using a solvent, or may be carried out using a solvent. However, from the viewpoints of adjusting the reaction temperature and achieving high purity of the obtained MPDAc(Z), it is preferable to carry out the reaction without a solvent.

[0031] The first step (esterification reaction) may be carried out under atmospheric pressure, or under pressure or reduced pressure. However, from the viewpoint of sufficiently increasing the reaction temperature, it is preferable to carry out the reaction under atmospheric pressure or pressure, and more preferably under pressure. The upper limit of the pressure (gauge pressure) when pressurizing is preferably, for example, 5 kPaG, more preferably 3 kPG. The lower limit of the pressure (gauge pressure) when pressurizing can be, for example, 0.1 kPaG.

[0032] In the first step, it is preferable to reuse at least a part of the acetic acid (W) removed from the system together with water for the esterification reaction in this step. When removing water by fractional distillation, a part of the acetic acid (W) having a boiling point of 118° C. under 1 atmosphere is usually removed at the same time. Therefore, by reusing the distilled acetic acid (W) as a raw material, the raw material can be used efficiently and waste can be reduced. When reusing acetic acid (W), a part of the water distilled together with acetic acid (W) may be added again to the reaction system. However, from the viewpoint of reaction efficiency, it is preferable to remove as much water as possible and add (reuse) acetic acid (W) to the reaction liquid. The acetic acid (W) used as a raw material may be a combination of the recycled acetic acid and other acetic acid (W).

[0033] The first step can be completed by stopping the addition of acetic acid (W). It is preferable to continue to heat the product liquid (a solution containing the produced MPDAc (Z) and the like) obtained through the reaction at a predetermined temperature thereafter to advance the esterification reaction and to distill off water and the like sufficiently. At this time, heating may be performed under reduced pressure. In this way, MPDAc (Z) with higher purity can be obtained in higher yield. After stopping the addition of acetic acid (W) in this way, in other words, after the completion of the first step, the molar ratio (W / (X+Y+Z)) may be less than 0.010.

[0034] (Second process) The method for producing MPDAc preferably further comprises a second step of esterifying MPDA (X) using acetic anhydride following the first step. In the esterification reaction using acetic acid (W), the reaction rate decreases when the esterification proceeds to a certain extent because the proportion of water remaining in the reaction system becomes relatively high compared to the ester compound. The esterification reaction is accelerated by lowering the proportion of water. Therefore, by adding acetic anhydride, the acetic anhydride reacts with the water present in the reaction system and consumes water to produce acetic acid, thereby accelerating the reaction rate. In addition, acetic anhydride has a higher esterification reactivity than acetic acid. Therefore, by further proceeding with the esterification reaction using acetic anhydride following the first step using acetic acid (W), MPDAc (Z) can be obtained more efficiently and in a higher yield.

[0035] The amount of acetic anhydride used in the second step is, for example, preferably 0.05 to 0.6, more preferably 0.1 to 0.5, in terms of molar ratio relative to the raw material MPDA (X). Some of the acetic acid produced by using acetic anhydride is consumed by the esterification reaction, and some is removed from the system together with water. The amount of acetic anhydride used can be set to a relatively small range as described above, and can be sufficiently reduced by vacuum distillation or the like, which will be described later. Therefore, unlike the case where the esterification reaction is carried out using only acetic anhydride, it is not necessary to neutralize at least two equivalents of the by-product acetic acid produced. However, a neutralization treatment may be carried out to adjust the liquid property as necessary.

[0036] The lower limit of the reaction temperature in the second step is preferably 130° C., more preferably 140° C. By setting the reaction temperature to the above lower limit or higher, the esterification reaction can be more fully promoted. On the other hand, the upper limit of the reaction temperature is preferably 180° C., more preferably 170° C., and even more preferably 160° C. By setting the reaction temperature to the above upper limit or lower, polymerization of MPDAc(Z) can be suppressed, and the yield can be increased.

[0037] The reaction atmosphere, the presence or absence of a solvent, etc. in the second step can be the same as in the first step.

[0038] The first or second step is preferably carried out until the molar ratio (Z / (X+Y+Z)) of MPDAc(Z) to the total amount of MPDA(X), MPMAc(Y) and MPDAc(Z) in the reaction system (reaction solution) becomes 0.95 or more, furthermore 0.96 or 0.97 or more. In this way, MPDAc can be produced in a high yield. The upper limit of this molar ratio (Z / (X+Y+Z)) may be 1, or from the viewpoint of production efficiency, it may be 0.999 or 0.99.

[0039] (Third step) In the method for producing MPDAc, it is preferable to provide a step of purifying the product liquid containing the obtained MPDAc (Z) after the first step and the second step performed as necessary. By carrying out the purification, the purity of the obtained MPDAc (Z) can be further increased. The purification of the product liquid can be effectively carried out by distillation, particularly vacuum distillation. This purification is preferably carried out so that the purity of MPDAc (Z) is 95% by mass or more, further 96%, 97% by mass or 98% by mass or more.

[0040] (Yield, etc.) The yield of MPDAc(Z) in the method for producing MPDAc is 95% or more, and preferably 96% or more or 97% or more. According to the method for producing MPDAc, MPDAc(Z) can be produced with such a high yield. The upper limit of this yield may be 100%, or from the viewpoint of production efficiency, it may be 99.9% or 99%. The yield is the ratio of the amount of a substance actually obtained (yield) to the maximum amount of the substance that can be theoretically obtained (theoretical yield). In the method for producing MPDAc, it is equal to the ratio of the amount of substance (number of moles) of the obtained MPDAc(Z) to the amount of substance (number of moles) of MPDA(X) used as a raw material.

[0041] The lower limit of the purity of MPDAc(Z) obtained by the method for producing MPDAc is preferably 90% by mass, more preferably 95%, 96% by mass, or 97% by mass, and the upper limit of this purity may be 100% by mass or 99.9% by mass.

[0042] The content of chlorine compounds in MPDAc(Z) obtained by the method for producing MPDAc is preferably 1,000 ppm or less, more preferably 100 ppm or less, and even more preferably 10 ppm or less or 1 ppm or less, calculated as chlorine atoms. Since the method for producing MPDAc does not use a compound containing chlorine element as a raw material, it is possible to obtain MPDAc(Z) with an extremely low content of chlorine compounds, which is industrially useful.

[0043] (Applications, etc.) The MPDAc obtained by the method for producing MPDAc can be used in various applications known in the art. MPDAc can be suitably used as a comonomer in producing modified ethylene-vinyl ester copolymer (modified EVOH). In particular, the MPDAc obtained by the method for producing MPDAc contains less impurities such as chlorine compounds, which is preferable because it can suppress corrosion of MPDAc tanks and transport drums, and is also useful in that it can produce modified EVOH with good color tone.

[0044] <Method of producing modified ethylene-vinyl ester copolymer> The method for producing a modified ethylene-vinyl ester copolymer (modified EVOH) of the present invention includes a step of copolymerizing the MPDAc obtained by the above-mentioned method for producing MPDAc, ethylene, and a vinyl ester, and a step of saponifying the obtained copolymer.

[0045] Such MPDAc-modified EVOH has the characteristics of having improved stretchability and shrinkability while maintaining good barrier properties compared to unmodified EVOH. In addition, according to the method for producing modified EVOH using MPDAC obtained by the method for producing MPDAc of the present invention, since the purity of the MPDAc used is high, it is possible to synthesize high-quality modified EVOH, and the productivity is excellent.

[0046] The modified EVOH can be produced in the same manner as in the conventionally known methods, except that the MPDAc obtained by the above-mentioned MPDAc production method is used. For example, the modified EVOH can be obtained by copolymerization and saponification in accordance with the method described in the above-mentioned Patent Document 1. EXAMPLES

[0047] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0048] The composition of the product liquid and the distillate is as follows: 1 Analysis was carried out by 1 H-NMR (400 MHz, JEOL Ltd.) and gas chromatography (GC). 1 The H-NMR measurement conditions are as follows. Measurement solvent: deuterated dimethyl sulfoxide Reference material: Tetramethylsilane Measurement temperature: 25℃ Number of times: 32 The assignment of each compound is as follows: MPDA: 5.0ppm(s, 2H), 3.9ppm(s, 4H) MPMAc: 5.1ppm(s, 1H), 5.0ppm(s, 1H), 4.5ppm(s, 2H), 3.9ppm(s, 2H), 2.0ppm(s, 3H) MPDAc: 5.2ppm(s, 2H), 4.6ppm(s, 4H), 2.0ppm(s, 6H) Acetic acid: 1.9 ppm (s, 3H) Titanium tetrabutoxide: 3.4 ppm (t, 8H), 1.4 ppm (q, 8H), 1.3 ppm (q, 8H), 0.9 ppm (t, 12H), Water: 2.5ppm(s, 2H), Acetic anhydride: 2.2 ppm (s, 6H) The other peaks detected were classified as other unknown substances. For the other unknown substances, the total integral value detected in the range of 0 to 6 ppm other than the above assignments was used to calculate the number of moles as a compound with a 6H hydrogen atom.

[0049] [Example 1] In a nitrogen atmosphere, 100 parts by mass (1.00 molar equivalent) of MPDA, 54.5 parts by mass (0.80 molar equivalent) of acetic acid, and 1.93 parts by mass (0.005 molar equivalent) of tetrabutoxytitanium were added to a reactive distillation apparatus equipped with a heat medium jacket and a stirrer, and the mixture was stirred. The reaction temperature (reaction liquid temperature) was heated to 150 ° C. by heating the heat medium jacket, and the esterification reaction was carried out under atmospheric pressure under conditions where the temperature at the top of the tower was 85 to 100 ° C. while refluxing. After 1 hour from the start of the reaction, additional 6.8 parts by mass (0.1 molar equivalent) of acetic acid was added every hour, and the reaction was carried out for a total of 20 hours. Water generated during the reaction was collected as a distillate in a condenser at the top of the tower, which was water-cooled to 10 ° C. The composition of the product liquid obtained after 20 hours of reaction was as shown in Table 2. The maximum and minimum values ​​of the molar ratio (W / (X+Y+Z)) in the reaction solution during the reaction were as shown in Table 1. These maximum and minimum values ​​were measured in deuterated dimethyl sulfoxide by sampling every hour before adding acetic acid. 1 The values ​​were calculated from the H-NMR spectrum (measurements were similar in other examples and comparative examples). Thereafter, the addition of acetic acid was stopped, and the reaction solution was stirred for another 3 hours under conditions of a reaction solution temperature of 100-150°C and reduced pressure to 600-400 Torr using a steam ejector, and distillation was continued until no more acetic acid or water was distilled out. After removing the distillate from the receiving vessel, the reaction vessel was reduced in pressure to 50 Torr, and MPDAc was extracted by vacuum distillation. The yield of the distilled MPDAc-containing solution, the purity (GC) of MPDAc, and the yield (yield after vacuum distillation x purity) were as shown in Table 2. In addition, the total amount of acetic acid used, the total content of MPDA (X), MPMAc (Y) and MPDAc (Z) in the distillate during the reaction, and the total mass of the raw materials used to produce 1 mole of MPDAc (Z) are as shown in Table 2. In addition, the chlorine content in the obtained MPDAc was analyzed by automatic combustion / ion chromatography, and the chlorine content was found to be below the detection limit (5 ppm or less).

[0050] [Example 2] Except for extending the reaction time to a total of 22 hours, the synthesis of MPDAc was carried out in the same manner as in Example 1. The results of analysis, etc. are shown in Tables 1 and 2.

[0051] [Example 3] Except for extending the reaction time to a total of 24 hours, the synthesis of MPDAc was carried out in the same manner as in Example 1. The results of analysis, etc. are shown in Tables 1 and 2.

[0052] [Example 4] MPDAc was synthesized in the same manner as in Example 1, except that the reaction temperature (reaction liquid temperature) was 160° C. under a pressure of 0.5 kPaG and the reaction time was changed to a total of 18 hours. The results of analysis, etc. are shown in Tables 1 and 2.

[0053] [Example 5] MPDAc was synthesized in the same manner as in Example 1, except that the reaction temperature (reaction liquid temperature) was 180° C. under a pressure of 1.8 kPaG and the reaction time was changed to a total of 16 hours. The results of analysis, etc. are shown in Tables 1 and 2.

[0054] [Example 6] Except for changing the amount of tetrabutoxytitanium to 3.86 parts by mass (0.010 molar equivalents) and changing the reaction time to a total of 18 hours, MPDAc was synthesized in the same manner as in Example 1. The results of analysis, etc. are shown in Tables 1 and 2.

[0055] [Example 7] Except for changing the reaction temperature (reaction solution temperature) to 140° C. and the reaction time to 24 hours in total, the synthesis of MPDAc was carried out in the same manner as in Example 1. The results of analysis, etc. are shown in Tables 1 and 2.

[0056] [Example 8] Except for changing the reaction temperature (reaction solution temperature) to 130° C. and the reaction time to 28 hours in total, the synthesis of MPDAc was carried out in the same manner as in Example 1. The results of analysis, etc. are shown in Tables 1 and 2.

[0057] [Comparative Example 1] Except for changing the reaction temperature (reaction solution temperature) to 118° C. and the reaction time to 40 hours in total, the synthesis of MPDAc was carried out in the same manner as in Example 1. The results of analysis, etc. are shown in Tables 1 and 2. When the reaction temperature was low, the esterification reaction rate was very slow, and it was not possible to efficiently obtain the target product with high purity and high yield.

[0058] [Example 9] MPDAc was synthesized in the same manner as in Example 1, except that the amount of acetic acid charged was changed to 132.8 parts by mass (1.95 molar equivalents), the reaction temperature (reaction liquid temperature) was changed to 132° C., and the reaction time was changed to 28 hours in total. The results of analysis, etc. are shown in Tables 1 and 2.

[0059] [Comparative Example 2] MPDAc was synthesized in the same manner as in Example 1, except that the amount of acetic acid charged was changed to 170.3 parts by mass (2.50 molar equivalents), the reaction temperature (reaction liquid temperature) was changed to 118° C., and the reaction time was changed to 40 hours in total. The results of analysis, etc. are shown in Tables 1 and 2. When the amount of acetic acid charged and the amount of acetic acid in the reaction solution during the reaction are large, the temperature of the reaction solution in the reflux state becomes low, and therefore the reaction temperature cannot be sufficiently increased under normal pressure, and it is not possible to efficiently obtain the target product with high purity and high yield.

[0060] [Example 10] MPDAc was synthesized in the same manner as in Example 1, except that the amount of acetic acid charged was changed to 34.1 parts by mass (0.50 molar equivalents) and the reaction temperature (reaction liquid temperature) was changed to 160° C. The results of analysis, etc. are shown in Tables 1 and 2.

[0061] [Example 11] MPDAc was synthesized in the same manner as in Example 1, except that the amount of acetic acid charged was changed to 6.8 parts by mass (0.10 molar equivalents), the reaction temperature (reaction liquid temperature) was changed to 180° C., and the reaction time was changed to 25 hours in total. The results of analysis, etc. are shown in Tables 1 and 2.

[0062] [Example 12] MPDAc was synthesized in the same manner as in Example 1, except that the amount of acetic acid charged was changed to 3.4 parts by mass (0.05 molar equivalent), the reaction temperature (reaction liquid temperature) was changed to 180° C., and the reaction time was changed to 25 hours in total. The results of analysis, etc. are shown in Tables 1 and 2.

[0063] [Comparative Example 3] MPDAc was synthesized in the same manner as in Example 1, except that the amount of acetic acid charged was changed to 0.68 parts by mass (0.01 molar equivalent), the reaction temperature (reaction liquid temperature) was changed to 190° C., and the reaction time was changed to 25 hours in total. The results of analysis, etc. are shown in Tables 1 and 2. The yield was low, possibly due to polymerization of MPDAc caused by the high reaction temperature.

[0064] [Comparative Example 4] Except for using p-toluenesulfonic acid monohydrate (0.005 molar equivalent) as a catalyst instead of tetrabutoxytitanium, MPDAc was synthesized by esterification reaction in the same manner as in Example 1. The results of analysis, etc. are shown in Tables 1 and 2. When p-toluenesulfonic acid monohydrate was used as a catalyst, MPDAc could not be obtained in high purity and high yield.

[0065] [Comparative Example 5] In a nitrogen atmosphere, 100 parts by mass (1.00 molar equivalent) of MPDA and 231.7 parts by mass (2.00 molar equivalent) of acetic anhydride were added to a reactive distillation apparatus equipped with a stirrer and a cooling jacket, and the reaction solution was stirred and cooled to a reaction solution temperature of 0°C. Here, 1.39 parts by mass (0.010 molar equivalent) of N,N-dimethylaminopyridine was added and stirred. Subsequently, 229.7 parts by mass (2.00 molar equivalent) of triethylamine was added, and the reaction solution was stirred at a temperature of 0°C for 1 hour, after which the jacket temperature was raised to 25°C over 2 hours to carry out an esterification reaction. 200 parts by mass of 2N hydrochloric acid was added to the reaction solution obtained, and the mixture was stirred and allowed to stand, whereby the mixture was separated into an upper organic phase containing the target substance and a lower aqueous phase. After removing the aqueous phase, the organic phase was washed with 200 parts by mass of a saturated aqueous sodium carbonate solution, and the aqueous phase was removed. The organic phase was then circulated through a dryer filled with molecular sieves, whereby the moisture content was dried to 10 ppm or less. The yield of the obtained MPDAc was 186.5 parts by mass, the purity (GC) was 96.0% by mass, and the yield was 91.6%. Although the target product was obtained with high purity, the yield was low because the MPDAc was partially dissolved in the aqueous phase.

[0066] [Comparative Example 6] The reaction was carried out under the same conditions as in Example 1, except that the amount of acetic acid charged was 244 parts by mass (2.70 molar equivalents) and no acetic acid was added thereafter. The reaction temperature (reaction liquid temperature) did not rise above 118°C at the beginning of the reaction, and after the start of water distillation, the reaction temperature rose as the amount of distillate increased, and 5 hours after the start of the reaction, the reaction liquid temperature reached 150°C. The reaction was then carried out for another 35 hours. The yield of the solution containing MPDAc extracted by reduced pressure distillation was 182.0 parts by mass. The purity of MPDAc was 83.1% by mass. Compounds contained other than MPDAc were 1.6% by mass of MPDA and 14.1% by mass of MPMAc. When acetic acid was added all at once at the start of the reaction, the reaction temperature could not be increased, so the reaction rate was slow, and further, water and acetic acid formed an azeotropic mixture and were distilled out of the system, so the esterification reaction could not proceed sufficiently.

[0067] [Example 13] In a nitrogen atmosphere, 100 parts by mass (1.00 molar equivalent) of 2-methylene-1,3-propanediol, 54.5 parts by mass (0.80 molar equivalent) of acetic acid, and 1.93 parts by mass (0.005 molar equivalent) of tetrabutoxytitanium were added to a reactive distillation apparatus equipped with a heat medium jacket and a stirrer, and the mixture was stirred. The reaction temperature (reaction liquid temperature) was heated to 150°C by heating the heat medium jacket, and the esterification reaction was carried out under atmospheric pressure under conditions where the temperature at the top of the tower was 85 to 100°C while refluxing. After 1 hour from the start of the reaction, additional 6.8 parts by mass (0.1 molar equivalent) of acetic acid was added every hour, and the reaction was carried out for a total of 20 hours. Water generated during the reaction was collected as a distillate in a condenser at the top of the tower, which was water-cooled to 10°C. The maximum and minimum values ​​of the molar ratio (Y / (W+X+Z)) in the reaction liquid during the reaction were as shown in Table 1. Thereafter, the addition of acetic acid was stopped, and 34.8 parts by mass (0.3 molar equivalents) of acetic anhydride was further added and reacted at 150°C for 2 hours. The composition of the reaction liquid after the reaction was as shown in Table 2. Stirring was continued for another 3 hours under conditions of a reaction liquid temperature of 100 to 150°C and reduced pressure to 600 to 400 Torr by a steam ejector, and distillation was continued until the distillate of acetic acid, water and acetic anhydride was no longer produced. After removing the distillate from the receiving tank, the reaction tank was reduced in pressure to 50 Torr, and MPDAc was taken out by distillation under reduced pressure. The yield of the distilled MPDAc-containing liquid, the purity (GC) of MPDAc, and the yield (yield after reduced pressure distillation x purity) were as shown in Table 2. In addition, the total amount of acetic acid used, the total content of MPDA (X), 2-methylene-1,3-propanediol monoacetate (Y) and MPDAc (Z) in the distillate during the reaction, and the total mass of the raw materials used to produce 1 mole of MPDAc (Z) are shown in Table 2.

[0068] [Table 1]

[0069] [Table 2]

[0070] In Tables 1 and 2 above, "-" indicates that there is no corresponding data or that the data has not been acquired.

[0071] As shown in Tables 1 and 2, MPDAc could be efficiently obtained in high purity and high yield in each of the production methods of Examples 1 to 13. Furthermore, when comparing Example 2 and Example 13, which have the same reaction temperature and total reaction time, it can be confirmed that the yield and purity of MPDAc are increased by adding acetic anhydride at the end of the esterification reaction.

[0072] Table 2 also shows the results of evaluation of the total mass of the raw materials used in producing 1 mole of MPDAc(Z) according to the following criteria. A: Less than 300g B: 300g or more and less than 400g C: 400g or more In each of the production methods of Examples 1 to 13, the total mass of the raw materials can be reduced, and it can be said that the methods are excellent in terms of productivity, environmental load, and the like.

Claims

1. A method for producing 2-methylene-1,3-propanediol diacetate (Z) in a yield of 95% or more using 2-methylene-1,3-propanediol (X) as a raw material, comprising the steps of: A method for producing 2-methylene-1,3-propanediol diacetate, comprising: a first step of carrying out an esterification reaction of 2-methylene-1,3-propanediol (X) using acetic acid (W) in the presence of a titanium-containing catalyst at a reaction temperature of 130° C. or higher and 180° C. or lower while adding acetic acid (Z) to the reaction system so that the molar ratio (W / (X+Y+Z)) of acetic acid (W) to the total amount of 2-methylene-1,3-propanediol (X), 2-methylene-1,3-propanediol monoacetate (Y), and methylene-1,3-propanediol diacetate (Z) in the reaction system is maintained in the range of 0.010 to 1.95, and while removing water generated at the same time from the system.

2. The method for producing 2-methylene-1,3-propanediol diacetate according to claim 1, further comprising a second step of carrying out an esterification reaction of 2-methylene-1,3-propanediol (X) using acetic anhydride following the first step.

3. The method for producing 2-methylene-1,3-propanediol diacetate according to claim 1 or 2, wherein at least a portion of the acetic acid (W) removed from the system together with water in the first step is reused for the esterification reaction in the first step.

4. The method for producing 2-methylene-1,3-propanediol diacetate according to any one of claims 1 to 3, further comprising a third step of purifying the product liquid containing the obtained 2-methylene-1,3-propane diacetate (Z) so that the purity is 95% by mass or more.

5. A step of producing 2-methylene-1,3-propanediol diacetate by the method for producing 2-methylene-1,3-propanediol diacetate according to any one of claims 1 to 4; A step of copolymerizing the obtained 2-methylene-1,3-propanediol diacetate with ethylene and a vinyl ester; and A step of saponifying the obtained copolymer The method for producing a modified ethylene-vinyl ester copolymer comprises:

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