JPS59199655A - Preparation of methylated amine compound - Google Patents

Abstract

PURPOSE:To obtain a methylated amine compound having high discoloration resistance, low occurrence of discoloration with time, and excellent storage stability, by methylating an amine compound in the presence of a hydrogenation catalyst, and heating the reaction liquid in the presence of an alkaline metal salt. CONSTITUTION:An amine compound having at least one active haydrogen atom (e.g. ethylamine, N-amino-ethylpiperazine, etc.) is methylated in the presence of a hydrogenation catalyst (e.g. Raney-Ni, Pt, etc.) by conventional reducing methylation process. The reaction liquid obtained by the methylation reaction is incorporated with an alkaline metal salt (e.g. sodium haydroxide, potassium hydroxide, etc.) and heat-treated at 30-200 deg.C, preferably 60-150 deg.C to obtain the objective compound. USE:Useful as a synthetic intermediate of agricultural chemicals and pharmaceuticals, foaming catalyst for polyurethane, hardener for epoxy resin, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dyeing methylated amine compounds. More specifically, in the presence of a hydrogenation catalyst, at least one
In a method for producing a methylated amine compound by methylating an amine compound having 1 active hydrogen with formaldehyde and hydrogen, after the methylation reaction is completed, an alkaline gold salt is added to the reaction solution and heat treatment is performed. It is easy to purify, has little coloration, and has a 1.0% storage stability.
The present invention relates to a method for producing a methylated amine compound.

Methylated amine compounds are useful industrial chemicals that can be widely used as foaming catalysts for polyurethane intermediates in agricultural chemicals and pharmaceuticals, and as hardening agents. Several methods have already been proposed for producing alkylated amine compounds by alkylating amine compounds having active hydrogen. Among these, the method of obtaining an alkylated amine compound by reacting the amine compound with a carbonyl compound such as an aldehyde or ketone and hydrogen in the presence of a hydrogenation catalyst is widely known as the reductive alkylation method. Particularly The reductive methylation method using formaldehyde as a carbonyl compound is often used as an industrial method for producing methylated amine compounds (for example, "Organic Chemistry Handbook", pages 363-365, edited by the Organic Synthetic Chemistry Association, Gihodo (July 1962). (issued on May 10), Japanese Patent Application Laid-Open No. 123214/1984, etc.).

The desired methylated amine compound can be obtained from the reaction solution of this reductive methylation by a conventional fractional purification method such as distillation. However, the methylated amine compound produced by this known reductive methylation reaction is easily colored, and even if one with a low degree of coloring can be obtained by distillation etc.
It causes discoloration over time during storage and is extremely unstable in terms of quality. This phenomenon is particularly noticeable when producing permethylated amine compounds in which all the active hydrogens contained in the amine compounds are reductively methylated, and often causes trouble during storage.

On the other hand, in the reductive methylation method, if a precursor of a methylated amine compound or a resinous substance produced by the reaction of an amine compound and formaldehyde is included in the reductive methylation reaction solution, hydrolysis occurs in the distillation process. Generates trace amounts of formaldehyde. In particular, in the production of the above-mentioned permethylated amine compounds, formaldehyde is usually added to the required chemical buffer in order to improve the yield of the desired permethylated amine compounds and to facilitate distillation separation from unreacted amine compounds. Spears are used excessively. For this reason, when distilling 1+ijl of the target methylated amine compound from the reaction solution, formaldehyde coalesces on the surface of the cooler and arrives as a white resinous substance, causing operational problems and, in history, This leads to a serious problem of iron contamination in the product amine compound.

As described above, the known methods have problems in terms of quality such as coloring of the product and in terms of distillation efficiency, and no effective solution has yet been found.

The inventors of the present invention took into consideration the above-mentioned circumstances, and as a result of conducting a negligent inspection, it was discovered that in the reductive methylation method, as long as an alkaline metal salt is added to the obtained reductive methylation reaction solution and heat treatment is performed, the coloration is extremely low. In particular, methylated amine compounds with low occurrence of coloring over time and excellent storage stability are produced, and furthermore, the desired amine compound is purified from the reaction solution by # distillation. The present invention was achieved by discovering advantageous facts such as the fact that discipline often occurs.

The present invention provides a method for producing a methylated amine compound by dimethylating an amine compound having at least one active hydrogen by a reductive methylation method in the presence of a hydrogenation catalyst.
By adding an alkaline metal salt to the reductive methylation reaction solution obtained by the reductive methylation reaction and heat-treating it, a methylated amine compound with a low degree of coloration and excellent storage stability is produced in a simple manner. The aim is to provide extremely useful industrial technology.

Next, the method of the present invention will be explained in more detail.

According to the method of the present invention, the amine compound that can be used as a raw material is not particularly limited as long as it has at least one active hydrogen in its molecule and can be subjected to known reductive methylation methods. For example, ethylamine.

diethylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine,
triethylenetetraamine, morpholine, piperazine,
Examples include aliphatic or aromatic amines such as N-amino-ethylpiperazine, ethanolamine, jetanolamine, aminoethylethanolamine, cyclohexylamine, benzylamine, and aniline.

These raw material amine compounds are converted into methylated amine compounds by a reductive methylation method, and the reductive methylation reaction can be carried out by a known method.

That is, a hydrogenation catalyst and a raw material amine compound are charged with a solvent if it is safe, and the reaction is carried out by heating and stirring in a hydrogen atmosphere at normal pressure or under pressure, and sequentially adding formaldehyde solution 1i, for example, formalin. It's fine.

As the hydrogenation catalyst for the reductive methylation reaction in the method of the present invention, metallurgical catalysts such as Raney nickel, Raney nickel, platinum, rhodium, and ruthenium are used.

When a solvent is used, water, methanol, ethanol, ethers such as dioxane, tetranohydrofuran, etc. are used. Formaldehyde is more convenient to use as 't47,
For example, it is preferable to use water, methanol, or a mixed solution thereof.

Furthermore, in order to obtain a methylated amine compound with high purity and high yield by the method of the present invention, it is necessary to
: It is preferable to use more than the stoichiometric amount of formaldehyde with respect to hydrogen, and the activity of the raw material amine compound is usually increased.
The amount may be in excess of 1 to 10 moles relative to hydrogen. It is better to carry out the reaction under pressure in a hydrogen atmosphere, and the pressure may be appropriately selected within the range of 1 to 2oo'4/crrIG. The reaction temperature is usually in the range from room temperature to 200°C.

According to the present invention, an alkaline metal salt must be added to the wax base methylation reaction solution obtained in this way, and the mixture must be heat-treated. Usable alkaline metal salts include those that exhibit basicity in aqueous solutions such as alkali metal or alkaline earth metal hydroxides or carbonates, and those that exhibit strong basicity are particularly desirable; IJum or potassium hydroxide is preferred. This alkaline metal salt is added as a solid or as a solution in water, alcohol such as methanol, or the like. Usually, the amount added should be 0.05 market weight or more based on the raw material amine compound. f to the upper limit of addition amount
There is no lttl limit, but usually 05-2? I1. ,tii,
The spear is clever. On the other hand, particularly when producing lp4 of a permethylated amine compound, the amount of alkaline metal salt added must be taken into consideration because the excess ε1- of formaldehyde includes an excessive amount of formaldehyde. That is, if the amount added is equal to -1 to the excess Ek of formaldehyde, the excess amount of formaldehyde can be removed. The objective of improving storage stability is not fully achieved. The amount of toshik added is preferably 1.05 times or more, particularly preferably 1.3 times or more, relative to formaldehyde, which causes excessive stinging. There is no upper limit to the amount added, but 3 equivalents or less is usually sufficient.

After the addition of the metal jaws, it is heat treated at a temperature ranging from 30 to 200C, preferably from 60 to 150C. In this heat treatment, after the reductive methylation reaction is completed, the hydrogenation catalyst is heated for 1 minute from the reductive methylation reaction solution.

However, it is also effective to add the metal salt to an amine compound such as hydrogen, 9 elements, argon, etc. in an inert gas atmosphere and heat treat it, but in order to fully realize the characteristics of the present invention, the reductive methylation reaction is After the completion of the treatment, the metal salt solution is immediately injected under pressure into the presence of hydrogen and a hydrogenation catalyst and continuously heated. The latter method involves immediately heating under the reaction conditions after the reductive methylation reaction is completed, by transferring the reaction solution or
There is no need for complicated operations such as changing the gas atmosphere, and the effect is even more significant in terms of storage stability.

There is no limit to the heat treatment time depending on the row, but there is a tendency that a longer heat treatment time is preferable. The selection difference is usually within the range of 0.5 to 2.0 hours.

Even if the length is made longer than necessary, the effect of the present invention will not be greatly improved.

The heat-treated reaction liquid thus obtained after the heat treatment is an almost colorless and transparent liquid. The heat treatment of the present invention and the technique of Ming (
In the known method of adding 1rj15. During this time, a significant melting process occurs.

Next, the desired methylated amine compound is separated and obtained from the heat-treated reaction solution using a core receiver without causing any trouble. The obtained methylated amine compound has an extremely good storage stability of 1/2.

In other words, the rate of coloring over time is low.1. (High quality is maintained.)

Hereinafter, the present invention will be explained based on Examples, but the present invention is not limited to these Examples.

Example 1 A stainless steel autoclave (SU) equipped with a magnetic stirrer
S316. Internal volume 1. OOOme), N-aminoethylpiperazine (Toyo Soda Kogyo Co., Ltd.) 180f and Raney Nickel (Yoken Fine Chemical Co., Ltd.).

NDI4T-90) 7.2 S' and water 1802 were charged as a solubilizer. After the air in the autoclave was sufficiently converted to iF+ with hydrogen, the temperature was raised in an air furnace from 1,000≧l'L. When the temperature of the liquid in the autoclave reached 90°C, a 37.0% & 1 degree formalin aqueous solution was injected using a fixed pump with a cable pressure of 501 < ylcrlG. At the same time, absorption of hydrogen was observed, so hydrogen was supplied from a separately installed hydrogen tank through a secondary pressure regulating valve and the reaction was carried out under constant pressure. After the constant rate supply was completed in 6 hours, the reaction was continued for 1 hour in the middle to complete the reaction.

The reductive methylation reaction solution obtained in this way was then added with a regular pump to add 20 ml of sodium hydroxide aqueous solution.
i16.7f was press-fitted and stirred for 1 hour to perform heat treatment.

The autocup 1) was then cooled to room temperature and purged with hydrogen gas. +%,! The jx treatment reaction solution was placed in a 1 ton polyethylene container and allowed to stand for about 4 hours to precipitate the Raney Ni, and then the supernatant was taken and separated from the catalyst. This heat-treated reaction solution was a clear, colorless liquid. In addition, as a result of quantitative analysis of this reaction liquid by gas chromatography, the yield of trimethylaminoethylpiperazine was 99.0%.

Furthermore, a portion of this reaction solution was subjected to a salt 9 storage test. In the storage test, the heat-treated reaction solution was stored at room temperature and changes in color were observed. The results are shown in Table 1. Examples Using the same equipment as in Example 1, diethylenetriamine (
Toyo Chidatsu Niji) 3 company products) 120! '', 8.4 V of Raney nickel, and 120 g of water as a bath medium.
7%) under aqueous pressure for 6 hours at a constant rate of #8.
1:1i4J reaction to that medo history 1. ! ′”, :, f
f<;, j and complete. Pull Hl] 20% Sodium hydroxide aqueous solution 233? was press-injected and heat-treated by stirring for 1 hour, followed by heat-treated reaction solution 14 which was subjected to reductive methylation in the same manner as in Example 1. This reaction was a clear liquid. Incidentally, as a result of quantitative analysis of this reaction solution using a gas chromatograph, the a ratio of pentamethyldiethylenetriamine was 97.5.

A portion of this reaction solution was taken and subjected to the same storage test as in Example 1. The results are shown in Table 1.

Comparative Example 1 Using N-aminoethylpiperazine as the raw material amine,
In the same manner as in Example 1, an aqueous formalin solution was supplied and the mixture was further stirred for 1 hour to complete the reaction. Example 1 was prepared from the reductive methylation reaction solution obtained by cooling the autoclave to room temperature without adding an alkaline metal salt or heat treatment.
The catalyst was separated in the same manner. At this time, the reaction liquid was a slightly yellowish liquid. A portion of this reaction solution was subjected to a compost preservation test. The results are shown in Table 1.

Comparative Example 2 Using diethylenetriamine as the raw material amine, an aqueous formalin solution was supplied in the same manner as in Example 2, and then 1
The reaction was completed by stirring for an hour. The autoclave was cooled to room temperature without addition of an alkaline metal salt or heat treatment, and the catalyst was separated from the resulting reductive methylation reaction solution in the same manner as in Example 1. At this time, the reaction liquid was a slightly yellowish liquid. A portion of this reaction solution was subjected to a salt 9 storage test. The results are shown in Table 1.

Table 1 Example 3 A heat-treated reaction solution obtained in the same manner as in Example 1 was starved using a rotary evaporator to separate most of methanol and water. At this time, the U condensate was a colorless liquid.

Next, a reflux condenser was installed in a column with an inner diameter of 27 holes and a diameter of 50α filled with a single ring sock (made of 5tMlφ glass).
This concentrated liquid was purified by distillation using a distillation column with a diameter of 11 mm. A 1 ton pear-shaped flask was used as the distillation column, and heated using silicone oil as a heating medium. Contained water was separated by atmospheric distillation, and trimethylaminoethylpiperazine was further separated by vacuum distillation.

The distilled product was a clear, colorless liquid, and the residue from the can was a slightly yellowish viscous liquid. A portion of the product was taken and subjected to a storage test. The results are shown in Table 2.

Example 4 Using a heat-treated reaction solution obtained in the same manner as in Example 2, the same operation as in Example 3 was carried out to separate the product pentamethyldiethylenetriamine.

The distilled product was a clear colorless liquid, and the remaining liquid from the can was a slightly yellowish viscous liquid.

A portion of the product was taken and subjected to a storage test. The results are shown in Table 2.

Comparative Example 3 Using the reductive methylation reaction solution obtained in the same manner as in Comparative Example 1, after catalyst separation, concentration and distillation purification were performed in the same manner as in Example 3. During vacuum distillation to separate the water contained, a white resinous polymer of formaldehyde adhered to the surface of the reflux condenser. For this reason, it became necessary to temporarily stop distillation and clean it.

The distilled trimethylaminoethylpiperazine was a very slightly yellowish 7 (ν) substance, and the liquid remaining in the can was a reddish brown viscous liquid. A portion of the product was taken and subjected to a preservation test. The results are shown in Shishi 2.

Comparative Example 4 Using the Dengen methylation reaction solution obtained in the same manner as in Comparative Example 2, after catalyst separation, concentration and distillation purification were performed in the same manner as in Example 3. An external phenomenon similar to that in Comparative Example 3 occurred in distillation 26, and the distillation was temporarily reduced to 1. Product pentamethyl
Diethylenetriamine was yellowish, and the remaining liquid in the can was black reddish brown. A portion of the product was subjected to a storage test.

The results are shown in Table 2.

Example 5 From the Ryogen methylation reaction solution obtained in the same manner as in Example 1,
After the catalyst was separated, 16.75' of an aqueous solution of 200% hydroxide was added to the total amount of the reaction solution, and heat treatment was performed at a temperature of 90° C. for 1 hour. From the heat-treated reaction solution thus obtained, 16 pieces of trimethylaminoethylbeverazine were separated in the same manner as in Example 3. The distilled trimethylaminoethylpiperazine was a clear liquid similar to the product of Example 3, but the remaining liquid in the can was a viscous liquid with six red colors as in Comparative Example 3. A portion of the product was subjected to a storage test.The results are shown in Table 2.

Table 2 365-

Claims (1)

[Claims] 0) Methylating an amine compound having at least one active hydrogen with formaldehyde and hydrogen in the presence of a hydrogenation catalyst.1. In the method for producing a methylated amine compound, 1. After the completion of the reductive methylation reaction, an alkaline gold salt is added to the reductive methylation reaction solution and heat-treated. Method. (2) The production method according to item (1), wherein the alkaline earth gold hj-Mii is sodium hydroxide or caritas hydroxide. (3) Methylated amine compound The manufacturing method according to claim (1), wherein the methylated amine compound is a caniper methylated amine compound.