JPH09151168A - Production of beta-alanine salt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a β-alanine salt useful as a raw material for producing a medicine, an agrochemical and a cosmetic in high yield by suppressing the formation of by-products. SOLUTION: The oxidative dehydrogenation reaction of 3-aminopropanol is carried out in the existence of an alkali metallic hydroxide or alkaline earth metallic hydroxide (e.g. NaOH), water and a catalyst containing copper (e.g. a developed Raney copper) at 100-210 deg.C to afford a β-alanine salt. Based on the amount of the 3-aminopropanol, an alkali(ne earth) metallic hydroxide is used in an equivalent amount or more and >=10wt.% water and 1-70wt.% catalyst are used. The high-purity β-alanine salt can simply be obtained in high yield at a low cost because of no need of purification processes for removing by-products due to remarkably suppress the formation of iminodipropionic acid, nitrilotripropionic acid, etc., as by-products.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a β-alanine salt. β-alanine salt is important as a raw material for manufacturing pharmaceuticals, agricultural chemicals, and cosmetics.

[0002]

Various methods are known as a method for producing β-alanine. Industrially, ammonia is added to acrylonitrile to prepare 3-aminopropionitrile (APN), and then It is synthesized by hydrolyzing the nitrile group with alkali.

This synthetic process is shown below.

Embedded image

The problem with the above reaction is that when APN is produced,
Another molecule of acrylonitrile is added to APN, and iminodipropionitrile (IDPN) is by-produced. IDPN also hydrolyzes when the nitrile group is hydrolyzed, and iminodipropionic acid (IDPA)
It becomes salt.

This by-product reaction is shown below.

Embedded image

Therefore, the β-alanine obtained by the above method contained a considerable amount of IDPA. Furthermore, nitrilotripropionitrile, which is a small amount of IDPN, to which one more molecule of acrylonitrile is added, is also by-produced, and this also undergoes the same hydrolysis reaction as in the case of IDPA, and nitrilotripropionic acid is by-produced.

This by-product reaction is shown below.

Embedded image

In order to reduce the production amount of IDPA and nitrilotripropionic acid in β-alanine, it is sufficient to increase the ammonia excess ratio with respect to acrylonitrile during APN production. The problem makes it unsuitable for industrial implementation. Further, a method of treating with an ion exchange resin or the like to remove IDPA from β-alanine is also known, but it is not practical because the process becomes complicated. Also, ID
By treating PA at high temperature in ammonia, β
-Methods of converting to alanine are also known. However, in this method, it is necessary to carry out the treatment reaction at a high temperature of 200 ° C. or more, which is dangerous, and thus it is difficult as an industrial manufacturing method.

As described above, the method for producing β-alanine using acrylonitrile as a starting material has many problems, and therefore, the development of a method for producing β-alanine that can be easily carried out industrially has been desired.

On the other hand, a method for obtaining aminoacetic acids by subjecting aminoethanol to an oxidative dehydrogenation reaction in the presence of a copper-containing catalyst has already been known (JP-A-60-41644 and JP-A-60-41645). JP-A-60-78948,
JP-A-60-78949, JP-A-60-97945
And JP-A-60-100545).

In these methods, aminoethanol used as a starting material is monoethanolamine,
It is either diethanolamine or triethanolamine and is limited to compounds having a nitrogen atom at the β-position of the hydroxyl group. Oxidative dehydrogenation of aminoethanols
It progresses relatively easily. Further, this reaction proceeds relatively selectively not only in the copper catalyst but also in the presence of the noble metal catalyst.
That is, it is considered that the nitrogen at the β-position with respect to the hydroxyl group has some role in the oxidative dehydrogenation reaction. Therefore,
It has been considered difficult to oxidatively dehydrogenate a compound having no nitrogen atom at the β-position with respect to the hydroxyl group. To the knowledge of the inventors, in order to obtain β-alanine, γ is required for the hydroxyl group.
There is no example in which an oxidative dehydrogenation reaction was directly attempted for 3-aminopropanol having a nitrogen atom at the position.

[0012]

DISCLOSURE OF THE INVENTION The present invention is to provide a method for industrially, conveniently and inexpensively producing β-alanine containing no IDPA or having a very small content.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to produce a β-alanine salt by an industrially simple method, and as a result, have found that the method is not the conventional method of adding acrylonitrile to ammonia, but the amino method. The present invention has been completed by finding that a β-alanine salt free of by-produced IDPA or having an extremely small amount can be obtained by directly oxidatively dehydrogenating propanol.

That is, the method for producing a β-alanine salt of the present invention comprises 3-aminopropanol, at least one selected from alkali metal hydroxides and alkaline earth metal hydroxides, water, and copper. It is characterized in that oxidative dehydrogenation is carried out in the coexistence with a contained catalyst. According to the method of the present invention, two hydrogen atoms are dehydrogenated from the —CH ₂ OH group of aminopropanol and oxidized to form a CO ₂ — group.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As the alkali metal hydroxides or alkaline earth metal hydroxides used in the method of the present invention, sodium hydroxide, potassium hydroxide, calcium hydroxide and the like are used, but especially hydroxides are used. Sodium, potassium hydroxide and the like are preferable. These may be used in any shape such as flakes, powders, pellets and aqueous solutions, but it is preferable to use them in an aqueous solution from the viewpoint of easy handling.

The amount of the alkali metal hydroxide or alkaline earth metal hydroxide used is preferably equivalent or more, more preferably 1.0 to 2 with respect to the aminopropanol used in the reaction. Within the range of 0.0 equivalent.

The oxidative dehydrogenation reaction of the method of the present invention is carried out in the presence of water. That is, by using water, it is possible to uniformly react aminopropanol with an alkali metal hydroxide or an alkaline earth metal hydroxide,
As a result, β-alanine is obtained in high yield. The amount of water used in the reaction is preferably 10% by weight or more, more preferably 50 to 5 with respect to aminopropanol.
It is within the range of 00% by weight.

The copper-containing catalyst used in the present invention is a catalyst containing copper as an essential component. The source of copper in the catalyst may be any substance containing copper, for example, metallic copper or an inorganic compound such as copper nitrate, sulfate, carbonate, oxide, halide or hydroxide. , Organic acid salts such as formate, acetate, propionate, lactate and the like can be used. The shape of the catalyst is not particularly limited, for example, a catalyst obtained by reducing the surface of metallic copper by oxidative dehydrogenation, a catalyst obtained by developing a Raney copper alloy with an alkaline aqueous solution, thermal decomposition of copper formate, copper carbonate, etc. And / or the activated copper or the like obtained by the reduction can be used as it is or after being supported on an alkali-resistant carrier.
Examples of preferred carriers include titanium oxide, zirconium oxide, silicon carbide and the like.

As the catalyst used in the present invention, among the above-exemplified catalysts, in particular, from the viewpoint of activity for reaction and life of the catalyst, expanded Raney copper and zirconium oxide carrier by coprecipitation method or impregnation method are used. It is preferable to use a supported copper catalyst.

An example of the reaction for producing β-alanine salt in the method of the present invention is shown below.

Embedded image

The amount of the catalyst used in the method of the present invention is preferably 1 to 70% by weight, more preferably 10 to 40% by weight, based on aminopropanol. The reaction temperature is 22 to prevent thermal decomposition and hydrogenolysis of the carbon-nitrogen bond of aminopropanol and the formed β-alanine.
It is preferably carried out at a temperature of 0 ° C. or lower, usually 100
To 210 ° C, more preferably 120 to 180 ° C.

The β-alanine salt-forming reaction in the method of the present invention is an oxidative dehydrogenation reaction and is accompanied by the generation of hydrogen. Therefore, it is preferable to lower the reaction pressure as much as possible from the viewpoint of the reaction rate. Usually, this reaction is carried out at a pressure equal to or higher than the minimum pressure for proceeding the reaction in a liquid phase, preferably 5 to 50 kg / cm.
It is done within the range of ² G. As the reaction operation method, any of batch method, semi-batch method and continuous method can be used.

In order to collect the desired product by the method of the present invention, the reaction mixture is filtered to separate the catalyst, and an aqueous solution of the desired β-alanine salt is obtained as a filtrate. Alternatively, the reaction mixture is allowed to stand and the catalyst is allowed to settle, and the desired aqueous solution of β-alanine is separated and collected as a supernatant, which is appropriately purified as necessary to obtain a high-quality β-alanine salt as a product. Obtainable. On the other hand, the catalyst separated by filtration or sedimentation can be recovered and reused as it is in the next reaction. Of course, the recovered catalyst may be subjected to a regeneration treatment as needed and used.

Since the β-alanine salt obtained by the method of the present invention has high purity, it can be directly used for the next reaction or use. If the presence of small amounts of unreacted aminopropanol is not allowed, it can be easily distilled off under reduced pressure. The removal of a small amount of by-product IDPN may be carried out by a known method, but its content is smaller than that synthesized from acrylonitrile, so that the load required for purification is small.

[0025]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples.

The conversion of aminopropanol and the selectivity of β-alanine in the following examples were calculated from the following formulas. Aminopropanol conversion rate (%) = (number of moles of reacted aminopropanol) / (total number of moles of aminopropanol subjected to reaction) × 100 β-alanine selectivity (%) = (of produced β-alanine Number of moles) ÷ (Number of moles of reacted aminopropanol)
× 100

Example 1 210 g of aminopropanol, 123 of sodium hydroxide
g, 262 g of water, and 21 g of expanded Raney copper were charged into an autoclave having an internal volume of 1 liter, the inside of the autoclave was replaced with nitrogen gas three times, and then the reaction temperature was set to 160.
The reaction was carried out under conditions of ℃ and reaction pressure of 10 kg / cm ² G until the generation of hydrogen disappeared. The time required for the reaction is 160
It was 3 hours after the temperature was raised to ℃. After completion of the reaction, the reaction solution was cooled and the catalyst was filtered off. When the filtrate was analyzed, the conversion of aminopropanol was 99% and the selectivity of β-alanine was 90%. It was confirmed that the by-product was only IDPANa, and that there was no production of Na nitrilotripropionate.

Example 2 210 g of aminopropanol and 168 of potassium hydroxide
g, 289 g of water, and 42 g of Raney copper were charged into a 1-liter autoclave, and the inside of the autoclave was replaced with nitrogen gas three times, and then hydrogen was no longer added under the conditions of a reaction temperature of 120 ° C. and a reaction pressure of 10 kg / cm ² G. The reaction was carried out until the generation of The time required for the reaction was 7 hours after the temperature was raised to 120 ° C. After completion of the reaction, the reaction solution was taken out and analyzed, and it was found that the conversion of aminopropanol was 90% and the selectivity of β-alanine was 87%.

Comparative Example 1 500 g of 176 g of concentrated aqueous ammonia (concentration: 29% by weight)
After being charged into a ml autoclave and heated to 100 ° C., 53 g of acrylonitrile was introduced under pressure into the autoclave over 30 minutes. The mixture was heated at 100 ° C. for 30 minutes to subject the acrylonitrile to the addition reaction of ammonia. After completion of the reaction, the autoclave was cooled, the reaction solution was taken out, and ammonia was removed from the reaction solution under reduced pressure. AP at this time
The yield of N was 48% based on acrylonitrile. When the APN / IDPN ratio (weight ratio) of the reaction solution was analyzed, 6
It was 2/38. 40 g of NaOH was added to this reaction solution, and the nitrile group was hydrolyzed by heating and stirring at 70 ° C. for 1 hour. When the obtained β-alanine Na aqueous solution was analyzed, the yield of β-alanine was 4 with respect to acrylonitrile.
5%. The β-alanine / IDPA / nitrilotripropionic acid ratio (weight ratio) was 64/35/1.

[0030]

Industrial Applicability According to the method of the present invention, β-alanine salt as an objective compound from aminopropanol, by-products such as iminodipropionic acid and nitrilotripropionic acid are significantly suppressed from the prior art, while being simple and high in yield. Can be manufactured in. Further, the method of the present invention makes it possible to produce β-alanine in a high yield and a high purity as compared with the conventional method synthesized from acrylonitrile. Therefore, according to the method of the present invention, the purification step for removing the by-product is not required, and the operation only needs to filter the catalyst after the reaction, and a huge equipment for removing ammonia is not required. As a result, the production cost of β-alanine can be significantly reduced, and industrial implementation becomes easy.

Claims (1)

[Claims] 1. Oxidative dehydrogenation of 3-aminopropanol in the presence of at least one selected from alkali metal hydroxides and alkaline earth metal hydroxides, water, and a copper-containing catalyst. A method for producing a β-alanine salt, comprising: