JPS6318930B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention involves self-condensation of 2,2-dimethyl-3-hydroxypropanal (hereinafter referred to as OPA) to produce 2,2-dimethyl-1, which has excellent thermal stability.
The present invention relates to a method for producing 3-propanediol hydroxypivalic acid monoester (hereinafter referred to as EDO) in a high yield in a short period of time. EDO is a type of ester glycol with a neo-structure, and is mainly used in polyester, polyurethane, plasticity, lubricating oil, etc., so it is required to have excellent thermal stability, transparency, and hydrolysis resistance. Conventionally, a method of heating OPA in the absence of a catalyst is known as a method for producing EDO by self-condensing OPA (US Pat. No. 3,057,911). but
Simply heating OPA results in a slow reaction rate and cannot be put to practical use industrially.For this reason, many methods have been proposed in which the reaction is carried out in the presence of various catalysts (Tokuko Sho).
46-41888, JP-A-49-51218 and others). However, even if the reaction is carried out in the presence of a catalyst, the reaction rate is not necessarily sufficient, and the resulting reaction product may be colored due to thermal decomposition or the yield of the desired EDO may be significantly impaired. In particular, when an amine compound is used as a catalyst, colored EDO with a Hazen color number of 400 may be obtained, and unsaturated polyester resins obtained from such raw materials are colored slightly yellow and their commercial value is significantly reduced. It becomes what it is. Furthermore, methods of producing and decolorizing EDO colored in this way are being considered, but these methods are complicated to operate and are not sufficiently effective, making it difficult to produce EDO of excellent quality in a short time and at a high yield. A manufacturing method was desired. The present invention solves such drawbacks, and OPA is heated at an absolute pressure of 8 to 8 in the absence of a catalyst.
Self-condensing at 43mmHg and temperature below 200℃,
This is a method in which the reaction is carried out while the produced EDO is continuously or intermittently extracted from the reaction system by a reactive distillation method. In the present invention, the absence of a catalyst means not only that no catalyst is added during the reaction, but also that amines, potassium carbonate, and other basic substances used in the manufacturing process of OPA used as a raw material are removed from the raw material in advance. includes. As a method for purifying the raw material OPA, publicly known methods such as distillation, solvent extraction, and recrystallization methods can be applied. The temperature of the self-condensation reaction is 200°C or less. 200℃
In this case, the amount of side reaction products generated increases due to thermal decomposition of the generated EDO, resulting in coloring of the EDO and a decrease in yield. In the present invention, it is produced by a reactive distillation method.
By performing the reaction while continuously or intermittently extracting EDO from the reaction system, OPA can be self-condensed in the absence of a high concentration of EDO, and the reaction can be continuously performed at a high initial velocity. As a result, the reaction ends in a short time. Furthermore, since EDO is not exposed to heating for a long period of time, no side reaction products are generated, and EDO can be obtained in high yield. The reactive distillation method is when OPA is selectively self-condensed inside the distillation column while substances with a lower boiling point than OPA (solvent, water, and other impurities) are removed by distillation. Since it accumulates at the bottom of the column due to the difference in boiling point, this is extracted continuously or intermittently. This reactive distillation method can be carried out in a continuous, semi-continuous or batch manner, and the operating pressure is
It is necessary to maintain the temperature of the part with the highest concentration of OPA (the bottom of the column in a continuous distillation column) in the range of 160 to 200℃, which is 8℃.
Equivalent to ~43mmHg (absolute pressure). The internal structure of the reactive distillation apparatus may be any structure as long as it has a certain degree of rectification effect; for example, general distillation column structures such as packed column type, buttful tray type, bubble cap type, sieve tray type, etc. can be used as is. . Moreover, the heating method can be performed by preheating the raw material and reboiler at the bottom of the column. According to the present invention, it is possible to obtain highly pure EDO with a high yield and high reaction rate by a simple means, and the obtained EDO does not require a catalyst removal step.
It can be made into a product as is or with a simple process. Next, the present invention will be explained in more detail with reference to Examples. "%" and "part" in Examples and Comparative Examples
Unless otherwise specified, "% by weight" and "parts by weight" are respectively meant. Example 1 OPA 96.3% produced from isobutyraldehyde and formaldehyde using triethylamine as a catalyst, recrystallized from water, and obtained by removing triethylamine.
2,2-dimethyl-1,3-propanediol
Undried OPA with a composition of 0.1% and 3.5% water
was heated and melted at 95°C and fed to the center of the reactive distillation column at a feed rate of 1410 parts/hour. In the reactive distillation column, the column top pressure is 18 to 20 mmHg, and the column top temperature, column center temperature, and column bottom temperature are each 55 to 20 mmHg.
Operated at 60°C, 165-168°C and 175-180°C. A water-based fraction is continuously extracted from the top of the reactive distillation column at a distillation rate of 59 parts/hour, and a self-condensation reaction product liquid is continuously extracted from the bottom of the reactive distillation column at a distillation rate of 59 parts/hour. I pulled it out. At this time, the average residence time in the reactive distillation column was 0.84 hours. The composition of this reaction product liquid was as follows. OPA 0.05% or less 2,2-dimethyl-1,3-propanediol
0.28% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 0.11% EDO 98.9% Water 0.01% Other unknown components 0.65% The color of this reaction liquid was less than 10 in Hazen color number. Example 2 Produced from isobutyraldehyde and formaldehyde using triethylamine as a catalyst, extracted with toluene to remove triethylamine.
OPA50.4%, 2,2-dimethyl-1,3-propanediol 0.8%, water 4.3% and toluene 44.2
OPA extract with a composition of % was heated to 60 °C and 2460
It was continuously fed to the center of the reactive distillation column at a feeding rate of 1 part/hour. In the reactive distillation column, the column top pressure is 18 to 20 mmHg, and the column top temperature, column center temperature, and column bottom temperature are each 55 to 20 mmHg.
Operated at 60°C, 165-168°C and 175-183°C. A fraction containing toluene as a main component at 1288 parts/hour was extracted from the top of the reactive distillation column, and 1172 parts/hour of a self-condensation reaction product liquid was continuously extracted from the bottom of the reactive distillation column. The average residence time in the reactive distillation column at this time was 0.97 hours. The composition of this reaction product liquid was as follows. OPA 0.05% or less 2,2-dimethyl-1,3-propanediol
0.46% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 0.10% EDO 98.9% Other unknown 0.49% The color of this reaction liquid was Hazen color number 10. Example 3 Produced from isobutyraldehyde and formaldehyde using triethylamine as a catalyst and purified by vacuum distillation to remove triethylamine.
OPA with a composition of 96.8% OPA, 1.4% 2,2-dimethyl-1,3-propanediol, and 1.8% EDO
was continuously fed into the center of the reactive distillation column at a feed rate of 1500 parts/hour. The reaction distillation column has a pressure at the top of the column of 25 to 26 mmHg, a temperature at the top, a temperature at the center of the column, and a temperature at the bottom of the column, each of 70 to 26 mmHg.
It was operated at 73°C, 176-183°C and 188-190°C. A self-condensation reaction product liquid of 1498 parts/hour was continuously withdrawn from the bottom of the reactive distillation column. The average residence time in the reactive distillation column at this time was 0.76 hours.
The composition of the reaction product liquid was as follows. OPA 0.1% 2,2-dimethyl-1,3-propanediol
2.1% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 0.2% EDO 97.1% Other unknown 0.5% The color of this reaction liquid was Hazen color number 10. Example 4 OPA 95.1%, 2,2- produced from isobutyraldehyde and formaldehyde using sodium hydroxide as a catalyst, recrystallized from water, and obtained by removing the catalyst.
Dimethyl-1,3-propanediol 2.4%, water
A self-condensation reaction was carried out in the same manner as in Example 1, except that undried OPA having a composition of 2.5% was used as the starting material. Table 1 shows the amount of the reaction product extracted from the bottom of the reactive distillation column, the average residence time in the reactive distillation column, the composition of the reaction product, and the color of the reaction product. Example 5 94.8% OPA, 1.9% 2,2-dimethyl-1,3-propanediol, 3.3% water obtained by manufacturing from isobutyraldehyde and formaldehyde using potassium carbonate as a catalyst, recrystallizing from water and removing the catalyst.
A self-condensation reaction was carried out in the same manner as in Example 1, except that undried OPA having the composition was used as the starting material. Table 1 shows the amount of the reaction product extracted from the bottom of the reactive distillation column, the average residence time in the reactive distillation column, the composition of the reaction product, and the color of the reaction product.

【table】

[Table] Example 6 Undried OPA obtained in the same manner as Example 1 was
The mixture was melted by heating to 0.degree. C. and fed to the center of the reactive distillation column at a feed rate of 925 parts/hour. The pressure at the top of the column is reduced to 8 to 10 mmHg in the reactive distillation column,
The column top temperature, column center temperature and column bottom temperature were operated at 50-53°C, 154-160°C and 165-167°C, respectively. A fraction containing water as a main component was extracted from the top of the reactive distillation column at a distillation rate of 46 parts/hour, and a self-condensation reaction product liquid was continuously extracted from the bottom of the reactive distillation column at 879 parts/hour. . The average residence time in the reactive distillation column at this time was 1.30 hours. Moreover, the composition of this reaction product liquid was as follows. OPA 0.07% 2,2-dimethyl-1,3-propanediol
0.31% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 0.20% EDO 98.87% Water 0.05% Other unknown components 0.50% The color of this reaction liquid was less than 10 in Hazen color number. Comparative Example 1 Undried product obtained in the same manner as Example 1
OPA was melted by heating to 95° C. and fed to the center of the reactive distillation column at a feed rate of 925 parts/hour. The reaction distillation column was operated at a reduced pressure of 2 to 3 mmHg at the top, and at temperatures at the top, center, and bottom of the column of 25 to 30°C, 131 to 136°C, and 140 to 145°C, respectively. A water-based fraction was extracted from the top of the reactive distillation column at a distillation rate of 31 parts/hour, and a self-condensation reaction product liquid of 894 parts/hour was continuously extracted from the bottom of the reactive distillation column. . The average residence time in the reactive distillation column at this time was 1.27 hours. However, the composition of the reaction product liquid contained a considerable amount of unreacted OPA, as shown below. OPA 7.40% 2,2-dimethyl-1,3-propanediol
0.15% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 0.10% EDO 91.80% Water 0.20% Other unknown components 0.35% The color of the reaction liquid was Hazen color number 10 or less. Comparative Example 2 Undried product obtained in the same manner as Example 1
OPA was melted by heating to 95° C. and fed to the center of the reactive distillation column at a feed rate of 925 parts/hour. The pressure at the top of the reaction distillation column is reduced to 95 to 100 mmHg, and the temperature at the top, center, and bottom of the column are each
It was operated at 85-90°C, 210-225°C, and 230-240°C. Self-condensation reaction product liquid was continuously extracted from the bottom of the reactive distillation column at a rate of 865.2 parts/hour, and distilled water was extracted from the top of the reactive distillation column at a rate of 59.8 parts/hour. Low boiling point organic substances including OPA were distilled out. The average residence time in the reactive distillation column was 1.30 hours. The composition of the reaction product liquid contained many side reaction products as shown below. Composition of the reaction product extracted from the bottom of the column OPA 0.02% 2,2-dimethyl-1,3-propanediol
1.15% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 0.93% EDO 87.20% Water 0.01% Other unknown 10.67% The color of the reaction liquid was Hazen color number 10. The composition of the distillate at the top of the reactive distillation column was as follows. OPA 12.04% 2,2-dimethyl-1,3-propanediol
2.17% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 0.84% Water 54.01% Other unknown 30.94% Comparative example 3 Produced using triethylamine as a catalyst, then distilled under reduced pressure to remove water and isobutyraldehyde. , OPA 98.4%, 2,2- obtained by distilling off low-boiling components such as methyl alcohol and most of triethylamine.
Dimethyl-1,3-propanediol 0.2%,
EDO 1.07%, triethylamine 0.1%, unknown 0.33
The procedure was the same as in Example 1, such as temperature and amount of extraction, except that crude OPA having a composition of % was used as the starting material. The average residence time in the reactive distillation column was 1.30 hours. Moreover, the composition of this reaction product liquid was as follows. OPA 0.10% 2,2-dimethyl-1,3-propanediol
2.11% 2,2-dimethyl-1,3-propanediol isobutyric acid monoester 1.43% EDO 94.95% Water 0.05% Other unknown components 1.36% The color of the reaction liquid was extremely poor with a Hazen color number of 400. Therefore, this reaction solution was redistilled in a packed distillation column with 15 distillation plates, but the hue could only be improved to a Hazen color number of 80. Comparative Example 4 OPA purified in the same manner as in Example 3 to which 0.2% by weight of tetraisopropyl titanate was added was fed to the center of the reactive distillation column at a feed rate of 1500 parts/hour as a starting material. From the start of the reaction until about 1 hour, the pressure at the top of the reaction distillation column was 25-26 mmHg, the temperature at the top, the temperature at the center of the column, and the temperature at the bottom were 70-73℃ and 176-183℃, respectively.
and 188 to 190°C, which was the same condition as in Example 3, but after that, the condition gradually deteriorated, and the composition of the reaction product liquid extracted from the bottom of the reactive distillation column 2 hours after the start of the reaction. When I analyzed it, I found the following. OPA 1.54% 2,2-dimethyl-1,3-propanediol
24.82% 2,2-dimethyl-1,3-propanediol isobutyric acid mono-ester 4.20% EDO 32.40% Water 0.01% Other unknown 37.03% As shown, there are many side reaction products and the reaction cannot proceed continuously. Nakatsuta.

Claims (1)

[Claims] 1 2,2 dimethyl-3-hydroxypropanal in the absence of a catalyst at an absolute pressure of 8 to 43 mmHg and a temperature of
2, which can be produced by self-condensation at temperatures below 200℃.
2,2-dimethyl-, which is characterized in that the reaction is carried out while 2-dimethyl-1,3-propanediol/hydroxypivalic acid monoester is continuously or intermittently extracted from the reaction system by a reactive distillation method.
A method for producing 1,3-propanediol/hydroxypivalic acid monoester.