JP2000026356A - Production of hydroxypivalaldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently obtain hydroxypivalaldehyde that is useful as a raw material for polymers, medicines and as a synthetic intermediate for organic compounds by reaction of formaldehyde with isobutyraldehyde in the presence of a basic ion-exchange resin catalyst. SOLUTION: In the presence of a basic ion-exchange resin catalyst, 1 mole of formaldehyde is allowed to react with preferably 1.5-2.0 moles of isobutyraldehyde, preferably at 90-100 deg.C under a pressure for 2-8 hours to give the objective hydroxypivalaldehyde. In a preferred embodiment, the formaldehyde is used as a formalin solution of >=37 wt.% concentration and contains no or a small amount of methanol. The ion-exchange resin is filtered off from the resultant reaction mixture of hydroxypivalaldehyde before the low-boiling fraction mainly comprising unreacting isobutyraldehyde is distilled off. As this ion-exchange resin, can be used weak and strong basic ion-exchanges and a dimethylamine type ion-exchanger is preferred that has heat resistance over 100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing hydroxypivalaldehyde. This compound is an industrially useful compound as a raw material for a polymer, a raw material for a medicine, or an intermediate for organic synthesis, and has conventionally been produced by an aldol condensation reaction between formaldehyde and isobutyraldehyde.

[0002]

2. Description of the Related Art The aldol condensation reaction proceeds under any acidic basic conditions, but hydroxypivalaldehyde is condensed from a dimer to a tetramer under acidic conditions. Is generally performed under basic conditions. Conventionally, as a catalyst for synthesizing hydroxypivalaldehyde by an aldol condensation reaction between isobutyraldehyde and formalin, a strong basic substance such as an alkali metal or alkaline earth metal hydroxide or a tertiary amine such as triethylamine has been used. Is used. However, when a hydroxide of an alkali metal or an alkaline earth metal is used as a catalyst, severe heat is generated, and it is difficult to remove the heat by the conventional method, making it difficult to control the temperature. There was a problem that the rate and purity were reduced. Also the third
When a secondary amine is used, a trace amount of a nitrogen-containing by-product is generated, and it is difficult to remove the by-product. In any case, a step such as distillation is required to remove the remaining catalyst.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems associated with the prior art described above and to provide a method for efficiently producing high-purity hydroxypivalaldehyde by a simple method. It is in.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have obtained an aldol condensation reaction between isobutyraldehyde and formalin using a basic ion exchange resin as a catalyst. It has been found that hydroxypivalaldehyde of high purity can be produced efficiently. That is, the present invention relates to a method for producing hydroxypivalaldehyde, which comprises subjecting isobutyraldehyde and formalin to an aldol condensation reaction using a basic ion exchange resin as a catalyst.

BEST MODE FOR CARRYING OUT THE INVENTION

The formaldehyde used in the present invention may be an aqueous formaldehyde solution (formalin) or paraform, but the concentration of formalin is preferably as high as possible. That is, it is desirable that the raw material formalin has a concentration of 37% by weight or more and does not contain methanol or is as small as possible. The aldol condensation of isobutyraldehyde and formaldehyde in the present invention may be either a batch system or a continuous system. Although the reaction can be performed under normal pressure, the reaction under pressure is preferable. The charged molar ratio of isobutyraldehyde to formaldehyde was 0.9.
It is performed in the range of 5 to 2.50, preferably 1.5 to 2.
0.

The reaction temperature is 80 to 130 ° C., preferably 90
１００100 ° C. If the temperature is lower than 80 ° C., the reaction rate is low, so that it is not industrial. When the reaction temperature exceeds 130 ° C., undesirably, the amount of side reaction products increases and coloring occurs, which is not preferable. Since the boiling point of isobutyraldehyde is 63 ° C.,
When reacting under atmospheric pressure, the temperature cannot be raised to a higher temperature at the beginning of the reaction. After the ion exchange resin is filtered from the hydroxypivalaldehyde reaction product liquid thus obtained, unreacted low-boiling distillates containing isobutyraldehyde as a main component are distilled off according to a conventional method. The distilled low-boiling fraction is used by circulating the entire amount to the reaction system. The reaction solution from which the low boiling components have been distilled off can be used as it is in the next reaction, or hydroxypivalaldehyde can be separated by crystallization and used.

[0007] As the ion exchange resin used in the present invention, a weak or strong basic ion exchanger or a mixture thereof can be used. Particularly preferred ion exchangers are 10
It is a dimethylamine-type ion exchanger having a heat resistance of 0 ° C. or higher. The ion exchanger is preferably used in a commercially available granular form. When the reaction is performed discontinuously, for example in a stirring tank, the ion exchanger is 10-80 with respect to the total reaction solution.
An amount of% by volume, preferably 20 to 60% by volume, is used. It is also possible to continuously pass a mixture of isobutyraldehyde and formalin using ion exchange columns known in the art.

[0008] The reaction time is generally 0.5 hours or more, preferably 2 to 8 hours to complete the reaction.

[0009]

Industrial Applicability In producing hydroxypivalaldehyde by reacting formaldehyde with isobutyraldehyde, a high-purity hydroxypivalaldehyde was obtained in high yield by using a basic ion exchange resin as a catalyst. Further, the removal of the catalyst was easily performed by filtration, and the process was simplified.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the following examples, “%” and “part” mean “% by weight” and “part by weight”, respectively, unless otherwise specified.

Example 1 In a 1000 ml autoclave with a magnetic stirrer purged with nitrogen, 20
313 parts of isobutyraldehyde and 270.22 parts of 40% formalin were mixed and stirred at 45 ° C. The temperature of the reaction mixture was raised to 95 ° C. over 30 minutes. At this time, the internal pressure was 2.5 kg / cm ² . The reaction was further performed at 100 ° C. for 2 hours to obtain 128.5 parts of a reaction product liquid. Unreacted low-boiling components such as isobutyraldehyde were distilled off at a temperature of 60 to 65 ° C. and a pressure of 400 to 410 mmHg from the filtrate obtained by filtering the ion exchange resin from the reaction product solution. The composition of this reaction solution was analyzed using gas chromatography, and the result was 63.1% (yield 96.0%).

Example 2 The same operation as in Example 1 was performed by using Diaion SSA10 instead of Diaion WA30. The composition of the reaction solution after distillation of the low-boiling fraction was analyzed by gas chromatography to find that hydroxypivalaldehyde was 63.1% (yield 96.0%).

COMPARATIVE EXAMPLE 1 In a 1000 ml autoclave with a magnetic stirrer purged with nitrogen, 40
% 270.27 parts formalin, 312.47 isobutyraldehyde
And 144 parts of anhydrous sodium hydroxide, and the temperature was increased while stirring and maintained at 100 ° C. for 15 minutes. At this time, the reaction pressure was 4.2
kg / cm ² . The temperature of this reaction product is 60-65 ° C.
Under a pressure of 400 to 410 mmHg, unreacted low-boiling components such as isobutyraldehyde were distilled off. The composition of this reaction solution was analyzed by gas chromatography to find that hydroxypivalaldehyde was 59.76% (yield 91.1%).

COMPARATIVE EXAMPLE 2 In a 1000 ml autoclave with a magnetic stirrer purged with nitrogen, 40
% 270.27 parts formalin, 312.47 isobutyraldehyde
And 124.4 parts of anhydrous potassium carbonate, and the temperature was maintained at 100 ° C. for 30 minutes while stirring. At this time, the reaction pressure was 3.9 kg / cm ² . The temperature of this reaction product is 60-65 ° C and pressure 400-
At 410 mmHg, unreacted low-boiling components such as isobutyraldehyde were distilled off. The composition of this reaction mixture was analyzed by gas chromatography to find that hydroxypivalaldehyde was 61.73% (yield 94.1%).

Comparative Example 3 In a 1000 ml autoclave with a magnetic stirrer purged with nitrogen, 40
% 270.27 parts formalin, 312.47 isobutyraldehyde
And 10.93 parts of triethylamine, and the temperature was raised from room temperature to 90 ° C. over 1 hour with stirring. At this time, the reaction pressure was 1.2 kg / cm ² . The temperature of the reaction product
At 65 ° C. under a pressure of 400 to 410 mmHg, unreacted low-boiling components such as isobutyraldehyde were distilled off. The composition of this reaction solution was analyzed by gas chromatography to find that hydroxypivalaldehyde was 62.99% (yield 96.0%). When the same reaction solution was analyzed by a total nitrogen analyzer, 220 ppm
Of nitrogen was detected.

The main reaction conditions and results in the above Examples and Comparative Examples are summarized in Table 1. The yield, nitrogen content and metal content (total content of sodium and potassium) in Table 1 were measured by the following methods.

Measurement of Yield 10 mg of the reaction solution was diluted to a constant volume of 25 ml and subjected to gas chromatography (GC) analysis using GC510 manufactured by GL Science to measure and calculate the amount of reaction product produced. GC measurement conditions: FID detector, capillary column T
C-1701

Using a total nitrogen microanalyzer TN-10 manufactured by Mitsubishi Chemical Corporation, 10 mg of the reaction solution was directly analyzed to determine the nitrogen content. The detection limit is 3 ppm.

Measurement of Nitrogen Content Using a total nitrogen microanalyzer TN-10 manufactured by Mitsubishi Chemical Corporation, 10 mg of the reaction solution was directly analyzed to determine the nitrogen content. The detection limit is
3 ppm.

Measurement of Metal Content The total content of sodium and potassium was determined by diluting the reaction solution with water and using an atomic absorption spectrophotometer manufactured by Shimadzu Corporation. The detection limit is 0.1 wt%.

[0021]

[Table 1]

Claims (1)

[Claims] 1. A method for producing hydroxypivalaldehyde, comprising reacting formaldehyde with isobutyraldehyde in the presence of a basic ion exchange resin catalyst.