JPH10139737A - Production of highly purified trimethylamine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly purified trimethylamine useful as chemicals for electronic industries by adding a carboxylic acid ester to trimethylamine containing dimethylamine as an impurity to convert the dimethylamine to carboxylic amide, separating and purifying. SOLUTION: The objective highly purified trimethylamine is obtained in a high yield by adding a carboxylic acid ester (e.g. methyl formate) in an amount of 10-500 times mol of dimethylamine to trimethylamine containing dimethylamine as an impurity, reacting the dimethylamine with the carboxylic acid ester at 20-140 deg.C, preferably 40-100 deg.C for 5-180min, preferably 15-60min to convert the dimethylamine to the carboxylic amide (e.g. dimethylformamide) and separating the carboxylic amide from the trimethylamine by a usual distilling operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying high-purity trimethylamine which is a chemical for the electronics industry.

[0002]

2. Description of the Related Art Trimethylamine for general industrial use is separated and purified from a methylamine mixture by, for example, an extractive distillation method using water as described in Japanese Patent Publication No. 222061, and usually about 500 to 1,000 ppm. Contains dimethylamine as an impurity. This impurity concentration is in a sufficiently practical range for general industrial chemical use, but is not always at a satisfactory level for use as a raw material for a new chemical for the electronics industry, for example, tetramethylammonium hydroxide. Of trimethylamine is desired.

[0003]

The difference in boiling point between trimethylamine and dimethylamine is as small as 4 ° C., and the conventional distillation operation requires a high number of distillation columns in order to obtain a high degree of purification effect as in the present invention. In addition, since the distillation operation involves adding a large amount of water, a large amount of energy is required, which is not an industrially advantageous method. Accordingly, the present invention has been made to provide a method for producing high-purity trimethylamine which is advantageous for industrial implementation.

[0004]

In order to solve these problems, the present inventors have focused on a method of separating and purifying dimethylamine by converting it into a substance which can be easily separated from trimethylamine prior to distillation. As a result of diligent research, we found a method of reacting dimethylamine with a carboxylic acid ester by relatively simple treatment, selectively converting it to carboxylic acid amide, separating and purifying it, and obtaining high-purity trimethylamine. The present invention has been accomplished.

The present invention relates to a method for reacting dimethylamine contained as an impurity in trimethylamine with a carboxylic acid ester, for example, methyl formate, and converting it into dimethylformamide for separation. The boiling point difference between dimethylformamide and trimethylamine is about 150 ° C., which makes it very easy to separate and is itself a useful chemical. According to the present invention, the conversion effect of dimethylamine to carboxylic acid amide, and the separation and recovery thereof can be industrially advantageously carried out to significantly improve the purification effect of trimethylamine.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Trimethylamine, which is the subject of the present invention, contains dimethylamine as an impurity, and usually contains 10 to 500 times, preferably 20 to 300 times, moles of carboxylic acid ester of dimethylamine. In addition, dimethylamine is reacted with a carboxylic acid ester. The reaction temperature is usually 20 to 140 ° C, preferably 40 to 100 ° C, and the reaction time is usually 5 to 180 minutes, preferably 15 to 60 minutes. Since the carboxylic acid amide thus formed can be separated from trimethylamine by a known simple distillation operation, according to the present invention, trimethylamine containing substantially no dimethylamine can be industrially advantageously produced.

[0007]

According to the method of the present invention, it is possible to convert dimethylamine to carboxylic acid amide from trimethylamine containing dimethylamine as an impurity and to separate by distillation to obtain high-purity triethylamine in a very high yield. I can do it.

[0008]

Next, the present invention will be described more specifically with reference to examples.

Example 1 34 ml of methyl formate was charged in a 500 ml autoclave equipped with a magnetic stirrer.
After that, 234 g of industrial trimethylamine containing 440 ppm of dimethylamine were injected. Then
The autoclave was kept at 45 ° C. and reacted by stirring for 60 minutes. A part of the solution in the autoclave after the reaction was collected and subjected to gas chromatography analysis and ion chromatography analysis. No dimethylamine was detected, and dimethylformamide equivalent to dimethylamine was produced. At this time, the loss of trimethylamine as a formate was 0.001% of the charged amount, and the recovery of trimethylamine was 99.9% or more.
Further, the solution in the autoclave after the reaction was distilled to obtain trimethylamine. The yield of the obtained trimethylamine is
Dimethylamine was not detected in more than 99.9%.

Example 2 The same operation as in Example 1 was carried out except that the amount charged to the autoclave was 10 g of methyl formate and 220 g of trimethylamine, and the reaction was carried out at 87 ° C. for 60 minutes. After the reaction, dimethylamine was not detected, and dimethylformamide equivalent to dimethylamine was produced. At this time, the loss as formate was 0.05% of the charged amount, and the recovery of trimethylamine was 99.9% or more. Further, autocure after the reaction
The solution in the solution was distilled to obtain trimethylamine. The yield of the obtained trimethylamine was 99.9% or more, and dimethylamine was not detected.

Example 3 The same operation as in Example 1 was carried out except that the amount charged to the autoclave was 7 g of methyl formate and 206 g of trimethylamine, and the reaction was carried out at 34 ° C. for 60 minutes. Dimethylamine 8
4.8% was converted to dimethylformamide. At this time, the loss amount as formate is 0.001% or less of the charged amount,
The recovery of trimethylamine was 99.9% or more. Further, the solution in the autoclave after the reaction was distilled to obtain trimethylamine. The yield of the obtained trimethylamine is 9
At 9.9% or higher, 67 ppm of residual dimethylamine was detected.

Example 4 The same operation as in Example 1 was carried out except that the amount charged in the autoclave was 3 g of methyl formate and 234 g of trimethylamine, and the reaction was carried out at 85 ° C. for 60 minutes. Dimethylamine 8
7.9% was converted to dimethylformamide. At this time, the loss amount as formate is 0.001% or less of the charged amount,
The recovery of trimethylamine was 99.9% or more. Further, the solution in the autoclave after the reaction was distilled to obtain trimethylamine. The yield of the obtained trimethylamine is 9
Above 9.9%, 53 ppm of residual dimethylamine was detected.

EXAMPLE 5 An industrial trimethylamine containing 58 g of methyl formate and 950 ppm of dimethylamine was charged into an autoclave.
The same operation as in Example 1 was performed, except that the weight was changed to 205 g. No dimethylamine was detected, and dimethylformamide equivalent to dimethylamine was produced. At this time, the loss as formate was 0.001% or less of the charged amount, and the recovery of trimethylamine was 99.9% or more. Further, after reaction,
The solution in the reactor was distilled to obtain trimethylamine.
The yield of the obtained trimethylamine was 99.9% or more, and dimethylamine was not detected.

Example 6 The same operation as in Example 1 was carried out except that the amounts charged in the autoclave were 42 g of ethyl acetate and 210 g of trimethylamine. No dimethylamine was detected, and dimethylacetamide equivalent to dimethylamine was produced. At this time, the loss amount as acetate is 0.001% or less of the charged amount,
The recovery of trimethylamine was 99.9% or more. Further, the solution in the autoclave after the reaction was distilled to obtain trimethylamine. The yield of the obtained trimethylamine is 9
Above 9.9%, no dimethylamine was detected.

Claims (4)

[Claims] 1. A method for producing high-purity trimethylamine, comprising adding a carboxylic acid ester to trimethylamine containing dimethylamine as an impurity, reacting the carboxylic acid ester with dimethylamine, converting the compound into carboxylic acid amide, and then distilling off. 2. The method according to claim 1, wherein the carboxylic acid ester is methyl formate. 3. A reaction temperature of 20 to 140 ° C. and a reaction time of 5
3. The method according to claim 1 or 2, wherein the time is up to 180 minutes. 4. A carboxylic acid ester wherein dimethylamine is 1
The method according to claim 1, 2 or 3, wherein the molar ratio is 0 to 500 times.