JPH0366659A - Production of isethionic acid - Google Patents

Abstract

PURPOSE:To efficiently, industrially and readily obtain the subject compound useful as surfactants, etc., in high yield and purity for a short time by reacting anhydrous ammonium isethionate with anhydrous hydrogen chloride using a specific alcohol as a solvent. CONSTITUTION:Anhydrous ammonium isethionate is reacted with anhydrous hydrogen chloride in an equimolar amount to about 50mol% excess based on the aforementioned compound in a 1-3C alcoholic solvent, such as ethanol or isopropanol, preferably at ambient temperature to 80 deg.C to afford the objective compound useful in the field of resins, catalysts, etc. The weight ratio of the anhydrous ammonium isethionate used to the ethanol or isopropanol is preferably 10-60% and the above-mentioned mixing ratio is important for rapidly advancing the reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an improved method for producing isethionic acid, a compound useful in the fields of surfactants, resins, catalysts, and the like.

“Prior Art J Various methods have been proposed for producing isethionic acid, but U.S. Pat. No. 4,696,773 has already been disclosed as a method for easily isolating the produced isethionic acid. ing.

In the above method, isethionic acid of good quality can certainly be obtained in high yield, but the reaction solvent used is anhydrous lower alcohol, and the solubility of the raw material sodium isethionate in this solvent is extremely low. . Therefore, perhaps because the reaction with anhydrous hydrogen chloride occurs in a substantially non-uniform state, the reaction rate is slow and when the reaction temperature is raised to avoid this, undesirable side reactions such as decomposition occur, resulting in isethionic acid being obtained. quality has decreased.

"Problems to be Solved by the Invention" In order to solve the above-mentioned drawbacks, the present inventors focused on the solubility of isethionate salts and the economical efficiency of isolation of isethionic acid alone obtained by reaction with acid. As a result of further investigation, it was discovered that high-quality isethionic acid can be easily produced industrially by using an ammonium salt of isethionic acid, which has a high solubility in a specific alcohol, which has not been considered until now. reached.

"Means for Solving the Problems" That is, the present invention is a method for producing isethionic acid, which is characterized by reacting isethionic anhydride ammonium salt with anhydrous hydrogen chloride in the presence of an alcohol having 1 to 3 carbon atoms. .

In carrying out the method of the present invention, lower alcohols are used as a reaction solvent, examples of which include methanol, ethanol, n-propanol, isopropanol, etc., and the solubility of ammonium isethionate in these alcohols is that of sodium chloride. It is extremely large compared to that of salt.

For example, when comparing the solubility in ethanol at room temperature, in the case of ammonium salt, it is 3% by weight, while in the case of sodium salt, it is only 0.5%.

In this way, due to the difference in solubility, the rate at which the reaction with anhydrous hydrogen chloride proceeds in a homogeneous phase is an order of magnitude higher, and therefore, not only does the reaction proceed faster, but the formation of by-products during the reaction is suppressed, and the above simple substance separation becomes easy.

The mixing ratio of the above-mentioned alcohol solvent and isethionic acid ammonium salt is important for speeding up the reaction, and the weight ratio of the latter to the former is preferably 10 to 60%. 60%
If the amount used is above, the amount of dissolved ammonium salt of isethionate will decrease, which is not preferable, and if it exceeds 10%, not only will the amount of solvent used increase unnecessarily, but the reaction efficiency will deteriorate, which is not preferable.

In the method of the present invention, the ammonium salt of isethionate used may be obtained by any known method,
As an example of its production method, it is obtained by reacting acidic ammonium sulfite with ethylene oxide.

Both isethionic acid ammonium salt and hydrogen chloride, which are the raw materials for the method of the present invention, should be used in an anhydrous state.
By doing so, the purity and yield of isethionic acid alone can be increased. Similarly, the alcohol used as a solvent is preferably in an anhydrous state.

To explain in more detail, the isethionic acid ammonium salt and the above alcohols preferably have a water content of 1.0% or less, and as for hydrogen chloride, normally industrially available products may be used. , in that case the water content is too
ppm or less.

In carrying out the method of the present invention, the raw materials and the alcohols as the solvents mentioned above are placed in a reaction vessel.

In that case, there is no limit to the order in which the solvent is added, but for example, a method may be used in which the solvent is first added to the reaction vessel, then isethionic acid ammonium salt is added, and hydrogen chloride is added while stirring while keeping the temperature at a predetermined temperature, or alcohol as a solvent is added. Examples include a method in which hydrogen chloride is dissolved in advance in a mixture, and isethionic acid ammonium salt is added thereto to proceed with the reaction.

Generally, the reaction temperature should be at room temperature or above, but if the temperature is so high that decomposition of isethionic acid ammonium salt or isethionic acid itself is expected, it will cause a decrease in the quality of the product, which is not desirable. Therefore, the reaction temperature should be set at room temperature. The temperature is preferably above 80°C.

When carrying out the method of the present invention, the molar ratio of isethionic acid ammonium salt and hydrogen chloride may be equimolar, but in order to proceed with the reaction sufficiently, it is preferable to use a slight excess of hydrogen chloride, and the excess amount is 50% It is about X mol, and there is no need to use it in excess.

The reaction proceeds under the above conditions, and after completion, the ammonium chloride present as a solid in the reaction system is filtered off, and the reaction medium is further removed by distillation if hydrogen chloride is used in excess. Anhydrous and highly pure isethionic acid can be obtained. At this time, in order to avoid decomposition of isethionic acid, the distillation temperature is preferably the same as that during the reaction, even if it is high.

"Example" The method of the present invention will be explained in detail below with reference to Examples and Comparative Examples.

Example 1 37. Into a reaction vessel equipped with a stirrer, thermometer, and reflux condenser.
0 g of dry ammonium isethionate and 100 ml of ethanol were charged, and everything except the gas inlet was sealed. Thereafter, anhydrous hydrogen chloride gas was introduced into the mixture in the reaction vessel, which had been previously cooled to 20° C., at an average rate of 14 Q/Hr while stirring. The total amount of hydrogen chloride introduced was II,
It was 4g. The installation took about 30 minutes, but it went smoothly during that time. Further, the reaction temperature was maintained at about 50°C or lower.

After filtering and removing the generated ammonium chloride, ethanol and excess hydrogen chloride were removed by distillation under reduced pressure, yielding 33 g of isethionic acid as a residual liquid. This 2
It was cooled to 5°C and solidified. The yield is 100% based on the charged ammonium isethionate, and the purity is 99.8%.
Met.

Example 2 The apparatus used in Example 1 was charged with 37% dry ammonium isethionate. Og and isopropanol room'Q were charged, and 11.5 g of anhydrous hydrogen chloride was introduced into the mixture in the reaction vessel over about 40 minutes. During this time, the internal pressure was maintained at 0.7 atm and the reaction temperature was maintained at about 50°C or less. Cooling, filtration and vacuum distillation were performed to obtain 33.2 g of isethionic acid.

The yield was 10 oz and the purity was 99.7%.

Comparative Example 1 In the method described in Example 1, 38.5 g of dry sodium isethionate was used in place of ammonium isethionate, and the amount of anhydrous hydrogen chloride gas introduced was 14 Q /
When the reaction was carried out at 7 hr, the introduction stalled approximately 30 minutes after the start of introduction, and after that the introduction rate was lowered to 7 Q/hr and continued.
The process proceeded smoothly as in Example 1, and it took about 75 minutes to introduce a total of 11.5 g of anhydrous hydrogen chloride. The apparent yield was 100%, but the purity was less than 99%.

"Effects of the Invention" By using the method of the present invention, isethionic acid can be produced more efficiently and in a shorter time than conventionally known methods.

Claims (1)

[Scope of Claims] 1. A method for producing isethionic acid, which comprises reacting isethionic anhydride ammonium salt with anhydrous hydrogen chloride in the presence of an alcohol having 1 to 3 carbon atoms. 2. The alcohol is ethanol or isopropanol, and the weight ratio of the isethionic acid ammonium salt to ethanol or isopropanol is 0.1 to 0.6.
The manufacturing method according to claim 1.