JPS6039352B2 - Method for producing N-carboxymethyltaurine alkali salt - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing taurine derivatives.

In general, detergents consist of a surfactant as a main component and various additives including builders as subcomponents. The amount of the additive builder is greater than that of the surfactant, and it is also important in terms of increasing the cleaning power of detergents. Although many follower builders have been developed, the most widely used is tripolyphosphate.

However, despite its superior performance, tripolyphosphate has serious drawbacks in terms of environmental health. That is, when cleaning wastewater using a detergent containing tripolyphosphate enters a river, the phosphorus content causes eutrophication of the river and causes abnormal growth of algae. For this reason,
There is a demand for the development of a builder that does not contain IJ components, and in recent years, taurine derivatives have been attracting attention as this type of builder. (JP 50-149706) The present invention relates to a method for producing taurine derivatives. Specifically, the present invention involves adding a caustic alkali to taurine to form an alkali salt, reacting it with glycolonitrile, and then adding a caustic alkali to add hydration. The object of the present invention is to provide an industrially advantageous method for producing N-carboxymethyltaurine alkali metal salt and furthermore N-carboxymethyltaurine by decomposition. Conventional N-
Carboxymethyl taurine is synthesized from taurine and monochloroacetic acid, for example, in the above-mentioned Tsubaki Seki Sho 50-149706. However, this method uses expensive monoku as a raw material. By using acetic acid, N,N as a side reaction.
-The cost of N-carboxymethyltaurine increases as a result of the production of dicarboxymethyltaurine. Another method is to react taurine with soda cyanide and formalin, but in this case as well, the formation of N,N-carboxymethyl taurine as a by-product cannot be avoided, and the desired N-carboxymethyl taurine cannot be avoided. Taurine cannot be obtained with high purity and high yield. As a result of various studies on methods for efficiently producing N-carboxymethyl taurine, the present inventors found that after adding caustic alkali to taurine to form an alkaline salt, reacting it with glycolonitrile, and then adding caustic alkali to taurine. It has been found that by additionally performing hydrolysis, the formation of N,N-dicarboxymethyl taurine salt can be suppressed, and substantially only N-carboxymethyl taurine salt can be synthesized at an extremely high yield.

The method of the present invention will be explained in more detail below.

The caustic alkalis used in the present invention include caustic soda and caustic potassium, and these are usually used as aqueous solutions of about 20 to 5% by weight. The amount used is usually the theoretical amount, that is, 1 mol of caustic alkali is required per 1 mol of taurine.

When no caustic alkali is added, that is, when taurine is directly reacted with glycolonitrile rather than as an alkali salt, the desired reaction hardly progresses; Decomposition occurs and the purpose cannot be achieved. On the other hand, if an excessive amount of caustic alkali is added, the free caustic alkali promotes decomposition of glycolonitrile, coloring of the reaction solution, etc., which is not preferable. That is, it is necessary to add an equivalent amount of caustic alkaline urin. The glycolonitrile to be reacted with the taurine alkali salt is glycolonitrile prepared in advance or an aqueous solution thereof, and is usually used at a concentration of about 20 to 55% by weight. Directly reacting formaldehyde with hydrocyanic acid as a raw material instead of glycolonitrile means that even if a small amount of glycolonitrile is generated on the spot from hydrocyanic acid and formaldehyde during the reaction process, it is possible to use pre-produced glycolonitrile as a raw material. This is not preferable because N,N-dicarboxymethyltaurine is produced as a by-product, unlike in the case where the above method is used. The amount of glycolonitrile to be used may be a theoretical amount, that is, 1 mole of glycolonitrile per 1 mole of taurine. Although it is acceptable to use a slight excess of either one in the range of about 0.8 to 1.2 moles, there is no particular advantage.

If the amount of glycolonitrile is too large, unreacted residual glycolonitrile becomes nitrilotriacetic acid or glycolic acid during hydrolysis, which is undesirable as it causes contamination of impurities and coloring. In order to cause the two to react, it is best to gradually add the glycolonitrile aqueous solution to the taurine alkali salt aqueous solution and stir, or to mix equivalent amounts of both in small amounts. The reaction proceeds rapidly and at the same time generates a considerable amount of heat, raising the liquid temperature by 4 degrees. At this time, if the temperature is too high, the reaction solution will be colored, abnormal reactions will occur, and the temperature of the solution will further increase due to the heat of reaction, which is extremely dangerous and will cause side reactions, making it difficult to obtain the desired product in good yield. I can't even do that. The reaction temperature is usually preferably in the range of 10 to 60 q○. The reaction is completed in a short time, within 3 hours or 3 hours. The reaction solution thus obtained is then hydrolyzed with a caustic alkali.

As the caustic alkali, the same caustic soda and caustic potash as mentioned above are usually used in the form of an aqueous solution of 20 to 5% by weight. The amount used is usually a theoretical amount to a slight excess, that is, it is preferable to add about 1.0 to 1.5 moles of alkali per mole of glycolonitrile. In this case, an excessive amount of alkali suppresses side reactions and helps drive out the ammonia that is created. Although the reaction proceeds rapidly and generates heat and ammonia gas, the reaction can be carried out without any problems by mixing gradually or by thoroughly stirring the mixture. The reaction temperature is not necessarily limited, but if it is too low,
Since the reaction time is long, a range of 60 oo to boiling point is usually preferably applied. The reaction is completed in about 1 to about 3 hours. For use on hair, it is desirable to boil the reaction solution at least once before the end of the reaction in order to remove the ammonia created by the reaction. The reaction solution thus obtained contains highly purified N-carboxymethyltaurine alkali salt,
In addition to crystallizing N-carboxymethyltaurine alkali salt directly from this product, free N-carboxymethyltaurine can be obtained by means such as neutralization, fractional crystallization, or ion exchange treatment.

Hereinafter, typical examples of the method of the present invention will be shown and more specifically explained, but these are merely examples for explanation, and it goes without saying that the present invention is not limited to these. Needless to say, there are no restrictions. Example 1 A 4-wall hard glass flask equipped with a thermometer, a rope frame machine, a dropping funnel, and a reflux condenser was placed in a constant temperature oil bath.

Taurine 125% (1 mol), 5% by weight of alcoholic soda
80 parts (1 mol) of the solution and 90 parts of water were added and dissolved in a concentrated solution, and 114 parts (1 mol) of a 5% weight solution of glycolonitrile 5 at a concentration of 4000 or less was added dropwise thereto from the dropping funnel. After the dropwise addition was completed, the mixture was flooded and reacted at 50° C. for 1 hour. Then, 120 g of a 5% by weight solution of sodium hydroxide was added at once. A sudden heat generation occurred, the liquid temperature reached approximately 80q0, and ammonia began to be generated, but the mixture was further heated and allowed to react at the boiling point for 2 hours. After the reaction was completed, the liquid contained 218 ml of N-carpoxymethyl taurine soda. The yield from taurine is 96
%. This liquid was concentrated to obtain 218 crystals of N-carboxymethyltaurine sodium monohydrate.

The obtained yield was 89%. When this product was analyzed, the purity was 97%. Comparative Example Taurine 125 (1 mol) was added to the same device as Example 1.
Add 80 wt% solution (1 mol) of caustic soda 5 and 1632 wt% solution (1 mol) of cyanidating soda 3, and mix until concentrated. ) was added dropwise over 1 hour.

After the addition was completed, the mixture was flooded and reacted at 500° for 1 hour. Then 40 parts of a 5% by weight solution of caustic soda was added at once.

Claims (1)

[Claims] 1. N- which is characterized by adding a caustic alkali to taurine to form an alkali salt, reacting it with glycolonitrile to obtain N-cyanomethyltaurine, and then adding a caustic alkali to hydrolyze this. Method for producing carboxymethyl taurine alkali salt.