JPS6140219B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention discloses a method for producing unsaturated amides by catalytic hydration of unsaturated nitriles. Unsaturated amides are useful substances used as paper strength agents and synthetic raw materials for polymer flocculants. Copper catalysts are known as catalysts for catalytic hydration of unsaturated nitriles. A method for preparing copper catalysts is to treat copper oxide, copper hydroxide, and copper salts (salts of copper inorganic acids and organic acids) with hydrogen, formaldehyde, hydrazine, borohydride, hypophosphite, etc. Many methods have been disclosed, such as a method of treating with a metal having a strong ionization tendency, a method of decomposing copper formate, and a method of developing a Raney alloy. The inventors investigated these methods in detail and found that by reducing the copper compound,
Although it is possible to prepare a catalyst capable of synthesizing unsaturated amides, the resulting catalyst is not uniform in terms of activity and physical properties (bulk density, etc.), and various steps are required in the catalyst preparation stage. It was hot and not necessarily satisfying. In view of these circumstances, the present inventors conducted extensive research to find a catalyst that is easy to prepare and has excellent catalyst handling and activity, and found that it was obtained from ethylenediamine and copper salt. discovered that a copper catalyst obtained by contacting a copper complex compound with a water-soluble borohydride in an aqueous solution has excellent activity in the production of unsaturated amides through the catalytic hydration reaction of unsaturated nitriles, and completed the present invention. This is what I did. The unsaturated nitriles used in the present invention are acrylonitrile and methacrylonitrile. The copper complexes used in the present invention can be prepared from copper salts and ethylenediamine by known methods. The copper salt is not particularly limited as long as it is a water-soluble copper salt such as copper sulfate, copper nitrate, copper chloride, etc., but especially in the case of copper sulfate, ethylenediamine aqua copper can be obtained from an equimolar mixed solution of ethylenediamine. While it is possible,
It is preferable to use copper sulfate because other copper salts such as copper nitrate and copper chloride require twice the mole of ethylenediamine [crystals can be obtained as copper bis(ethylenediamine)]. The ratio of ethylenediamine to the copper salt is not particularly limited as long as it is added in a ratio corresponding to the theoretical amount of the copper complex. More specifically, when ethylenediamine is added to an aqueous solution containing a copper salt, a crystalline precipitate is obtained. If crystals cannot be obtained, a crystalline precipitate can be obtained by performing usual crystallization operations such as evaporation and concentration or cooling. A copper catalyst can be obtained by over-separating the ethylenediamine copper complex thus obtained, dispersing it in an aqueous solution, and bringing it into contact with a reducing agent. As the reducing agent, an alkali metal such as lithium, sodium, potassium, rubidium, etc.
Boron hydrides of alkaline earth metals such as beryllium, magnesium, and calcium are used in the form of an aqueous solution. In contacting the copper complex with the water-soluble borohydride, the copper complex can be used as an aqueous solution of any concentration, but is usually used at a ratio of about 0.01 to 3 moles per part of water. The reducing agent borohydride to act on the copper salt must be used in an amount of at least 0.2 moles, and 5 moles is sufficient, and 0.5 to 2 moles are preferably used. To bring the two into contact, a copper complex is dispersed in an aqueous solution, and a reducing agent is added dropwise to this. The temperature at which the reducing agent is brought into contact can be selected from a wide range from room temperature to the boiling point, but the reaction proceeds sufficiently at room temperature, so it is usually 20 to 40℃.
It is preferable to do it nearby. Further, the reduction operation is preferably carried out in an inert gas atmosphere, but it can also be carried out in the air. The precipitate thus obtained has a large particle size and good sedimentation properties and can be easily separated from the medium. The generated precipitate can be used as is, but
In order to avoid contamination of the unsaturated amide with decomposition products of the reducing agent, it is desirable to wash with water. Next, the hydration reaction in the method of the present invention will be explained. The hydration reaction is carried out by heating and reacting using the above-mentioned catalyst. There is no particular restriction on the amount of water used for the hydration reaction.
Although it can be carried out with less than the theoretical amount, it is usually 2~
It is best to use a 10-fold excess. It is preferable that the reaction temperature is usually in the range of 50 to 200°C. More preferably it is 70 to 150°C. Unsaturated amides can be produced at lower temperatures, but the reaction rate is slow, and higher temperatures increase the reaction rate but reduce the selectivity to unsaturated amides, which is not preferred. The amount of catalyst to be used in the reaction varies depending on whether the reaction is carried out continuously or in batches, and depending on the reaction format, but it is used at least 0.001 times (by weight), preferably at least 0.01 times, the amount of unsaturated nitrile. The reaction pressure is not particularly limited, but a pressure higher than the vapor pressure of the reaction liquid is required. This catalyst is particularly suitable for liquid phase reactions and is capable of both suspended bed and fixed bed reaction formats. The copper catalyst in the present invention shows excellent performance without a support, but can also be combined with a suitable support. In this case, activated carbon, silica, alumina, etc. can be used as the carrier. Next, the present invention will be specifically explained using examples, but the present invention is not limited to the following examples. () Preparation of catalyst Preparation example 1 50 g of cupric sulfate pentahydrate was dissolved in 300 ml of water, and an aqueous solution of 12 g of ethylenediamine dissolved in 50 ml of water was added dropwise with stirring. Next, the mixed aqueous solution was evaporated and concentrated on a water bath and left to stand to precipitate pale blue crystals. The crystals are separated by suction and dried under reduced pressure. 27 g of the obtained copper complex compound was suspended in 200 ml of water, and while stirring well at room temperature, 100 ml of an aqueous solution containing 11 g of sodium borohydride (NaBH ₄ ) was added.
was added dropwise over a period of 20 minutes. A brown precipitate formed from the blue solution as the sodium borohydride was added dropwise. Further after dripping
Stirring was continued for 30 minutes, and the resulting precipitate was washed twice with water and used as a catalyst. Preparation Example 2 When 12 g of ethylenediamine is added to a solution of 24 g of copper nitrate trihydrate dissolved in 200 ml of water, bis(ethylenediamine) copper dihydrate is precipitated. The crystals are separated by suction and dried under reduced pressure. Preparation Example 1 except that 34 g of the obtained complex compound was used.
A catalyst was prepared in the same manner as above. Preparation Example 3 Add 13.5g of cupric chloride to 200ml of water.
Add 12 g of ethylenediamine, evaporate and concentrate until a skin is formed, and cool to precipitate dihydrate crystals. The crystals are separated by suction and dried under reduced pressure. Preparation Example 1 except that 29 g of the obtained complex compound was used.
A catalyst was prepared in the same manner as above. Preparation Example 4 27 g of the complex compound obtained in Preparation Example 1 was suspended in 200 ml of water and stirred well at room temperature.
50 ml of an aqueous solution containing 7.0 g of lithium borohydride (LiBH ₄ ) was added dropwise over 20 minutes. After the dropwise addition was completed, stirring was continued for another 30 minutes, and the resulting precipitate was washed twice with water and used as a catalyst. Comparative Preparation Example 10 g of cuprous chloride was suspended in 200 ml of water, and while stirring at room temperature, 50 ml of an aqueous solution containing 7.5 g of sodium borohydride (NaBH ₄ ) was added dropwise over 20 minutes. After the dropwise addition was completed, stirring was continued for another 30 minutes, and the resulting precipitate was washed with water five times and used as a catalyst. () Nitrile Hydration Example 1 A stainless steel reaction tube with an inner diameter of 8 mm and a length of 60 cm was filled with 30 ml of the above prepared catalyst together with water. Next, it was placed in a constant temperature bath, and when the temperature reached 100° C., an aqueous solution of acrylonitrile (6% by weight) was introduced at a rate of 30 c.c./hour using a press-fit metering pump. It was taken out as a clear liquid through a filter built into the reactor. When the system became stable, the reaction solution was analyzed (high performance liquid chromatography) and the following results were obtained.

[Table] Ethylene cyanohydrin, acrylic acid, and an unknown substance were slightly observed as by-products. As is clear from this result, compared to the catalyst of the comparative example, the catalyst according to the present invention has a smaller bulk density and can be said to be a bulkier catalyst. Furthermore, the catalytic activity is high even when compared with the same volume, and it is clear that it is a highly active catalyst. Example 2 In order to examine the performance of the copper catalyst according to Preparation Example 1, 100 ml of the copper catalyst was charged together with 60 g of acrylonitrile and 540 g of water into an autoclave having an internal volume of 1, and a reaction was carried out for 1 hour and 30 minutes under specified conditions under an argon atmosphere. After the reaction was completed, the contents were analyzed by high performance liquid chromatography, and the results shown in the following table were obtained.

[Table] A slight amount of ethylene cyanohydrin was observed to be produced, but no other by-products were detected. Example 3 A hydration reaction of methacrylonitrile was carried out at 100° C. according to the method of Example 1. The catalyst used in Preparation Example 1 was used, and methacrylonitrile was fed into the reactor as a 25% by weight aqueous solution. The reaction solution was collected and analyzed by high performance liquid chromatography, and methacrylamide was produced with a methacrylonitrile conversion rate of 99%. Almost no side reaction products were detected.

Claims (1)

[Claims] 1. A copper catalyst obtained by contacting a copper complex compound obtained from ethylenediamine and a copper salt with a water-soluble borohydride in an aqueous solution in a method for producing an unsaturated amide by contacting an unsaturated nitrile with water. A method for producing an unsaturated amide, characterized by using.