JPH02295952A - Production of aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride - Google Patents

Abstract

PURPOSE:To obtain a compound useful as a cation forming agent for starch, cellulose, etc., through efficient removal of unreacted epichlorohydrin and by- products by reacting an aqueous solution of trimethylamine hydrochloride with epichlorohydrin. CONSTITUTION:An aqueous solution of trimethylamine hydrochloride is reacted with epichlorohydrin in the molar ratio of epichlorohydrin to trimethylamine hydrochloride of 1.05-1.20, more than equimolar amount to give a crude aqueous solution of 3-chloro-2-hydroxypropyltrimehylammonium chloride. Then the crude aqueous solution is brought into contact with steam in counter current under reduced pressure by packed column method, formation of 1,3-dichlorohydrin as a by-product is suppressed and unreacted epichlorohydrin is removed to give the aimed purified substance. The steam distillation by packed column method shortens purification time and is advantageous in terms of amount of steam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for obtaining an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride by reacting an aqueous solution of trimethylamine hydrochloride with epichlorohydrin.

[Conventional technology]

3-Chloro-2-hydroxypropyltrimethylammonium chloride (hereinafter abbreviated as CHA) is widely used as a cationizing agent for starch, cellulose, and the like. This is because if a cationizing agent is made to coexist with caustic alkali in an amount equal to or more than the molar amount of CHA, the cationic group can be easily introduced by reacting with the hydroxyl group in the molecule of starch or cellulose. A conventional method for producing CHA is to neutralize trimethylamine with the same hydrochloric acid to form a hydrochloride salt, and then react it with epichlorohydrin. This method tends to produce 1,3-dichlorohydrin as a by-product, and unreacted epichlorohydrin also remains in the product solution. If these 1,3-dichlorohydrin and unreacted epichlorohydrin are not removed and added to starch when used as a cationizing agent, they have a crosslinking effect, which may increase the concentration of the starch solution or cause gelation. Further, if unreacted trimethylamine salt M salt remains, an amine odor will be emitted. In order to solve such problems, for example, Japanese Patent Application Laid-Open No. 58-17434
In No. 9, trimedelamine hydrochloride and epichlorohydrin are continuously used in equimolar amounts during the above reaction, and the reaction temperature is maintained at 70'C or less to suppress the formation of 1,3-dichlorohydrin. is described, and also published in JP-A-54-3
0109M includes a method in which unreacted epichlorohydrin and by-products are distilled off by continuous topping under reduced pressure or normal pressure while adding water or steam to the aqueous solution of CHA obtained by the above reaction, or by condensation. Are listed.

(Problems to be Solved by the Invention) However, in the method of JP-A No. 58-174349, it is difficult to continuously use equimolar amounts of trimethylamine ml salt and epichlorohydrin in a large-scale apparatus. There is a problem that it tends to generate amine odor.

Furthermore, in JP-A No. 54-30109, water is added by charging the crude reaction liquid in a reaction vessel, heating it, and adding water dropwise when the water starts to distill off, and using steam, which is industrially useful. The specific method in this case has not been disclosed or considered.

(Means for Solving the Problems) The present invention is intended to solve the above problems, and includes:
CH from trimethylamine hydrochloride and epichlorohydrin
The purpose of the present invention is to provide an industrially useful method for producing A and further refining it.

That is, in the present invention, when reacting an aqueous solution of trimethylamine hydrochloride (a) with epichlorohydrin (b),
By using an equimolar excess of (b) to (a) and keeping the reaction temperature below 30°C, 3-chloro-2
- Obtaining a crude aqueous solution of hydroxypropyltrimethylammonium chloride, and then bringing the crude aqueous solution into countercurrent contact with steam in a packed column under reduced pressure to simultaneously distill off unreacted epichlorohydrin and by-produced 1,3-dichlorohydrin. A method for producing 3-chloro-2-hydroxypropyltrimethylammonium chloride, characterized by:

The first step of the present invention is shown by the following reaction formula.

-Main reaction- (CHA) (He = methyl group) -Side reaction 0 ■ The higher the reaction rate of the reaction (1) above, the less the amine odor of the product, and the higher the reaction temperature of the reaction (2). It's so easy to get up.

Therefore, the above reaction temperature is kept low to make it difficult for the side reaction (2) to occur, and even if the side reaction (2) does occur, a little epichlorohydrin is added to prevent the amine odor from remaining due to insufficient epichlorohydrin. need to be used in excess.

The appropriate excess is about 10%, and the molar ratio of epichlorohydrin to trimethylamine hydrochloride is 1.05 to 1.
．． It is preferable to keep it at 20. If it exceeds this range, a large amount of unreacted epichlorohydrin will remain, which will interfere with the purification process, and if it is below this range, an amine odor will remain when alkali is added to the product.

The reaction temperature needs to be controlled to 30'C or less, but since it is difficult to react at too low a temperature, it is preferable to control the dropwise addition of epichlorohydrin while cooling the mixture to maintain the temperature in the range of 10 to 25C.

For example, when trimethylamine aqueous solution (concentration 30% by weight), hydrochloric acid (35% by weight once), and epichlorohydrin are used as raw materials, the reaction solution composition is 40% by weight CHA.

The amounts are approximately 4% by weight of epichlorohydrin and 2% by weight of 1,3-dichlorohydrin.

Since residual epichlorohydrin and 1,3-dichlorohydrin in this composition have an adverse effect when used as a cationizing agent as described above, 10 pp of epichlorohydrin was added.
It is necessary to remove 1,3-dichlorohydrin to 40 ppm or less.

The second step of the present invention involves the removal of the above impurities, that is, the purification of the crude CHA aqueous solution.

Industrially, it is more effective to remove epichlorohydrin and 1,3-dichlorohydrin by steam distillation than by extraction with a solvent, but if steam distillation is carried out under normal pressure, the following reactions occur simultaneously, which is not preferable.

Therefore, it is necessary to carry out steam distillation under reduced pressure, but if the distillation is simply carried out under reduced pressure while adding steam, for example, 1.
In order to reduce the 3-dichlorohydrin concentration to 40 ppm or less, approximately 3 to 5 times as much water as the crude CHA aqueous solution must be distilled off, which requires a long time.

In the second step of the present invention, the crude CHA liquid and steam are brought into countercurrent contact under reduced pressure in a packed column to simultaneously distill off epichlorohydrin and 1,3-dichlorohydrin contained in the crude aqueous CHA solution.

Specifically, an exhaust pump is connected to the top of the column filled with filler to reduce the pressure inside the column. When the supply of steam is started from the bottom of the column, epichlorohydrin in the crude CHA aqueous solution and 1.
3-Dichlorohydrin is distilled off along with water vapor, and is condensed in a condenser installed between the top of the column and the exhaust pump to become a waste liquid. The purified CHA aqueous solution is drawn out from the bottom of the column as bottom liquid and becomes a product.

The degree of vacuum is preferably regulated by an exhaust pump and a steam inlet valve so as to be below 50° C. at the bottom of the column 70'CQ. Although it varies depending on the type of filler, it is preferable to operate at a small liquid/gas ratio as long as flooding does not occur. The filler used is made of synthetic resin such as polypropylene, polyethylene, or V;
One example is one made by 1.

The present invention will be explained below with reference to Examples and Comparative Examples.

Note that all composition percentages in the examples are mold units.

Example 1. Comparative Example 1 (1st step) Trimethy/L7 at a concentration of 30% was placed in a reaction tank (volume 2, glass lined) equipped with a stirrer, a thermometer, and a reflux condenser.
7min 850kCI (4,31k (1m01)) was charged, and while cooling, 35% HCf 450kg (4,3
1 kgmof) was added dropwise to neutralize. Subsequently, 9 (4.74 kgmol) was added dropwise to epichlorohydrin 438 in several portions over 6.8 hours so that the temperature inside the tank was 12 to 2 degrees Celsius. After dropping, the mixture was aged for 30 minutes. In this way, a reaction crude liquid of 1738 kfJ (A>) was obtained, and the analysis results were as follows.

CHA 39.1% Epichlorohydrin 4.1% 1.3-dichlorohydrin 2.1% The yield of CHA was 83.9% with trimethylamine 1.

For comparison, using the above reaction tank, 680 kg (3.45 kg mol) of trimethylamine with a concentration of 30% was mixed with 35% H
Neutralize with CJ1360kc+ (3,45 kgmol), then itaepichlorohydrin 3t9ka (3,45
kc+mol) was added dropwise over 0.5 hours. The reaction temperature was 20 to 65°C, and the crude reaction liquid 1 was aged for 30 minutes after dropping.
359kg was weighed 1q. The analysis results were as follows.

CHA 35.2% Epichlorohydrin 0.1% 1.3-dichlorohydrin 5.3% The yield of CHA was 73.7% based on trimethylamine.

(Second step) A column with a column diameter of 0.13 J and a filling height of
<13/4 B, made of polypropylene, void ratio 90%,
Packing filter 210TrL-1> was filled.

The above reaction crude liquid (A > 75 kg) was used as the test crude liquid, and supply of the crude liquid from the top of the column and steam from the bottom of the column was started. At steady state, the liquid supply rate was 13.111/hr, and the steam supply rate was 28 kg. /hr, liquid-gas ratio (L/G) 0.
45. The degree of vacuum is 20mmt1g at the top of the tower and 60mm at the bottom of the tower.
Hg.

The temperature was 24-21°C at the top of the column and 44-47°C at the bottom.

The supply of liquid was finished after 6 hours, and the bottom liquid was analyzed. The same operation was repeated two more times to roughly purify the bottoms, and the bottoms each time were analyzed. These are shown in the table below.

Example 2. Comparative Example 2 Reaction crude liquid 8 produced in the same manner as the first step of Example 1
69ohU (CHA 38.o%, 1,3-dichlorohydrin 5.7%, epichlorohydrin 2.0%) was packed in the same manner as in the second step of Example 1 using a column with a column diameter of 0.5 m and a packing height of 10 m. Purification was carried out under similar operating conditions using a reagent. The time required for 1 pass is 36 hours, and the required amount of water vapor is 19,300 kg. The analysis value of the bottom liquid is 1 paS
After S CHA 38.1%, 1,3-dichlorohydrin 0
．． 005%, and epichlorohydrin 0.001% or less. This bottom liquid was transferred to an evaporator and concentrated. The analysis values of the concentrated solution are CHA 60.2%, 1,3-dichlorohydrin 0.004% or less, epichlorohydrin 0.001
%, the required time was 15 hours, and the distillation amount was on the 319 side.

For comparison, 8,690 kg of the same reaction crude liquid was subjected to steam distillation using a reaction tank with a capacity of 13. Almost the same amount of water (epichlorohydrin, 1,
3-dichlorohydrin) were distilled off. The degree of vacuum is 6
0 to 70 mmH (), and the tank temperature was 45 to 50'G. 108 hours after the start, 20.0 OOfJ was distilled, and while decreasing the supply amount of condensate, a total of 31,400. i! water was distilled out.The analysis values of the reaction solution were 63.1% CHA and 0.1% 1,3-dichlorohydrin.
002%, epichlorohydrin o, ooi% or less.

As described above, the steam distillation method using a packed column according to the present invention is significantly advantageous in terms of the required time and amount of steam compared to the steam distillation method using a reaction tank.

〔Effect of the invention〕

According to the method of the present invention, the production of 1,3-dichlorohydrin is suppressed during the production of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHA) aqueous solution, and a packed column method is adopted for purifying the crude liquid. By steam distillation, CHAI! 1,3-dichlorohydrin and epichlorohydrin contained in the crude liquid can be efficiently removed without changing the concentration.

Generally speaking, as the filling height and column diameter are increased, the number of crude liquid processing ports per unit time increases, so that the purification time for batch-produced crude liquid can be significantly shortened.

Claims (1)

[Claims] When reacting an aqueous solution of trimethylamine hydrochloride (a) with epichlorohydrin (b), (b)
) in an equimolar excess and keeping the reaction temperature below 30°C to obtain a crude aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride, and then the crude aqueous solution was poured into a packed column under reduced pressure. The unreacted epichlorohydrin and by-produced 1,
A method for producing an aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride, which comprises simultaneously distilling off 3-dichlorohydrin.