JPS5931742A - Preparation of unsaturated amide - Google Patents

Abstract

PURPOSE:To improve the yield with a high activity in hydrating acrylonitrile or methacrylonitrile to give the titled compound, by using an aqueous homogeneous colloidal copper solution obtained by treating a copper salt with a hydroborate in the presence of a protective polymer. CONSTITUTION:Acrylonitrile or methacrylonitrile is reacted with water in the presence of a homogeneous colloidal copper as a catalyst to give the aimed compound. The homogeneous colloidal copper solution is synthesized by dissolving a protective polymer and a copper salt in water, and adding an aqueous solution of a hydroborate thereto. The hydroborate to be added is used in a molar amount of about 2 times of that of the copper salt. A water-soluble polymer having the protective colloid action, e.g. polyvinylpyrrolidone, is used as the protective polymer, and the residue equivalent amount thereof to be used is 5-60 times, preferably 10-40 times, of that of the copper salt. The copper salt is suitably used in an amount of about 1-30millimol based on one lwater.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing unsaturated amides,
Specifically, the present invention relates to a method for producing acrylamide, saccharide, or methacrylamide by catalytically hydrating acrylonitrile or methacrylonitrile in the presence of a homogeneous metal catalyst.

Methods are known for the catalytic hydration of nitriles in the presence of catalysts to produce the corresponding amides from unsaturated nitriles such as acrylonitrile, acrylonitrile, or methacrylonitrile. As a catalyst,
It is also known that heterogeneous metallic copper catalysts obtained by reducing copper salts with hydroborates exhibit activity. However, from a practical standpoint, it is desired to develop catalysts with even higher activity and selectivity.

Based on these results, the present inventors conducted intensive research and found that a homogeneous steel colloidal catalyst obtained by reducing a copper salt with a hydroborate in the presence of an appropriate protective polymer is unsaturated. It was found that it has extremely high activity and selectivity for nitrile water utilization.

The present invention was achieved based on this knowledge, and its purpose is to provide an industrially useful method for producing acrylamide and methacrylamide. This objective is achieved by reacting a homogeneous steel colloid aqueous solution obtained by treating a copper salt with a hydroborate in an aqueous solution in the presence of a protective polymer with acrylonitrile or methacrylonitrile. Ru.

To explain the invention in more detail, the method of the invention uses as a catalyst an aqueous homogeneous steel colloid solution obtained by reacting a copper salt with a hydroborate salt in an aqueous solution in the presence of a protective polymer. As the copper salt, monovalent or divalent water-soluble copper salts such as steel sulfate, copper chloride, copper nitrate, etc. can be used. Alkali metals as reducing agents!
, alkaline earth metal hydroborates are usually used in aqueous solution.

In the present invention, the reaction between copper salt and hydroborate is
It is necessary to carry out this process in the presence of a protective polymer, thereby making it possible to prepare a uniform and stable aqueous copper colloid solution. As the protective polymer, a water-soluble polymer having a protective colloid effect, such as poly(vinylpyrrolidone) and poly(vinyl alcohol), is used.

The amount of protective polymer added is usually 5 to 6 with respect to the amount of copper.
0 times residue equivalents, preferably 10 to 40 times residue equivalents are used. It is appropriate to use the copper salt in an amount of about 1 to 30 mmol per 11 parts of water.

By dissolving the above polymer and copper salt in water and then adding an aqueous solution of hydroborate, a homogeneous and stable aqueous copper colloid solution is immediately obtained. The hydroborate added at this time is usually used in an amount of about twice the amount of copper in order to cause the reduction reaction to occur completely. The use of even larger amounts of hydroborate is pointless and economically disadvantageous as it does not provide any particular benefits, and is not preferred as it increases the P₁ of the solution. In addition, the reduction reaction is usually 0 to 100°C, preferably 10 to 60°C.
It will be held in

The homogeneous steel colloid aqueous solution thus obtained is extremely stable under an inert atmosphere, and no change is observed even if it is left at room temperature for 10 days or more.

According to the invention, acrylonitrile or methacrylonitrile is reacted with water in the presence of the catalyst thus obtained. An appropriate amount of nitrile can be used as long as it forms a uniform liquid phase. The reaction temperature and pressure can be selected from a wide range in which the system remains in a liquid phase, but in consideration of the reaction rate and reaction equipment, the reaction temperature is usually 20 to 95°C, and the pressure of the reaction system is reduced to It is carried out at several atmospheres. Note that the reaction is carried out under an inert atmosphere so that copper is not oxidized.

As explained above, according to the present invention, high activity can be obtained by uniformly dispersing a very small amount of catalyst, and it is possible to obtain acrylamide with extremely high selectivity. Furthermore, the production of ethylene cyanohydrin, acrylic acid, and oligomers, which are often problematic in conventional methods, was not detected in the present invention.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 Copper sulfate pentahydrate 375m, P and poly(vinylpyrrolidone) (degree of polymerization 3240) 0. ．． 667 / water 27m
After adding 1 and completely dissolving it, 6 ml of an aqueous solution containing 11.5 ml of sodium tetrahydroborate was added while stirring at room temperature, and the color of the solution changed immediately.
The resulting solution became a blackish brown homogeneous solution. All systems during the reaction were kept under nitrogen gas atmosphere. Acrylonitrile 0.4847' was added to the catalyst solution thus obtained, and the mixture was heated to 80°C while stirring.
The mixture was kept for 2 hours to react.

After the reaction was completed, the contents were analyzed by gas chromatography, and it was found that acrylamide was produced almost quantitatively with a reaction rate of acrylonitrile of 215%, and no by-products were detected.

Example 2 The amount of poly(vinylpyrrolidone) (degree of polymerization 3240) was 0.
．． A catalyst was prepared as a homogeneous solution in the same manner as in Example 1 except that 167 and 1' were used. When this was used to react under the same reaction conditions as in Example 1, the acrylonitrile reaction rate was 28.0%, and acrylamide was produced almost quantitatively. No by-product formation was observed.

Comparative Example 1 Copper sulfate pentahydrate 675m! was prepared in the same manner as in Example 1 except that poly(vinylpyrrolidone) was not used. A catalyst was prepared from sodium totitrahydroborate 1 i, 3 m, P as a black precipitate. When this was used to carry out a reaction under the same reaction conditions as in Example 1, the production rate of acrylamide was 4.4%, and the production of ethylene cyanohydrin was observed at 0.1%.

Patent applicant Hidefumi Hirai 347-

Claims (1)

[Claims] A homogeneous steel colloid obtained by treating a selected copper salt with an alkali metal or alkaline earth metal hydroborate in the presence of a polymer having a protective colloid action is used as a catalyst. z1 Method for producing acrylamide or methacrylamide by water utilization of acrylonitrile or methacrylonitrile