JPS648610B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for isomerizing diacetoxybutene. It is known that diacetoxybutene isomerizes in the presence of a palladium catalyst or a platinum catalyst. For example, Industrial Chemistry Journal Vol. 72, p. 1096 (1969)
reported on the isomerization reaction using palladium chloride ()-benzonitrile complex or palladium acetate () as a catalyst, and in Japanese Patent Publication No. 18172-1983, platinum chlorine compounds such as chloroplatinic acid were reported. is described to be used as an isomerization catalyst. However, it is also known that these palladium catalysts or platinum catalysts are reduced under the reaction conditions, and that these catalysts lose their activity as isomerization catalysts when reduced to the metallic state. On the other hand, in order to compensate for these shortcomings, palladium,
Alternatively, a method has been proposed in which diacetoxybutene isomerized while supplying oxygen gas in the presence of a platinum halide compound (Japanese Unexamined Patent Publication No. 75017/1983). The present inventors investigated the isomerization catalyst for diacetoxybutene and found that the life of the catalyst can be extended by carrying out the isomerization reaction in the gas phase in the presence of a palladium catalyst supported on activated carbon and hydrogen chloride or hydrogen bromide. We have discovered that this can be extended, and have arrived at the present invention. The present invention will be explained in detail below. The diacetoxybutenes to be mutually isomerized in the process of the present invention can be cis or trans 1,4-
diacetoxybutene-2 and 3,4-diacetoxybutene-1; these diacetoxybutenes include, for example, palladium and selenium, tellurium,
Obtained by reacting 1,3-butadiene with oxygen and acetic acid in the presence of a catalyst consisting of bismuth or antimony (Japanese Patent Publication No. 50-23008,
Special Publication Showa 52-12171). The catalyst used in the process of the invention is palladium supported on activated carbon, and hydrogen chloride or hydrogen bromide is used as a cocatalyst. Examples of the palladium supported on activated carbon include palladium halides such as palladium chloride, but organic acid palladium such as palladium acetate and palladium propionate, and inorganic acid palladium such as palladium nitrate and palladium sulfate may also be used. Of course, it is also possible to use metallic palladium reduced using the reduction method described above. The concentration of palladium on the support can vary over a wide range from 0.1 to 20 wt%, but a range of 0.1 to 10 wt% is generally preferred. Hydrogen chloride or hydrogen bromide may of course be in a gaseous state, but it can also be in a liquid state diluted with water such as hydrochloric acid or hydrobromic acid, and it can also be supplied dissolved in advance in the reaction substrate diacetoxybutene. It is possible. The concentration of hydrogen chloride or hydrogen bromide in the reaction system can vary over a wide range from 0.1 to 10 mol% relative to diacetoxybutene, but is generally preferably in the range of 0.5 to 5 mol%. In the method of the present invention, the temperature is usually 180° to 300°C under normal pressure.
The reaction temperature is generally 200° to 250°.
A range of 0.degree. C. is preferred. Although it is not necessary to use a particular reaction solvent, it is preferable to carry out the reaction under a flow of an inert gas such as nitrogen or argon, or under a flow of diluted oxygen of 1 to 10%. At this time, the reaction may be carried out under slight pressure. It is possible. 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 unless it exceeds the gist thereof. Example 1 0.5 g of a catalyst was prepared by immersing 25 g of crushed coconut shell activated carbon (20 to 60 mesh) in a solution of 4.7 mmol of palladium sulfate dissolved in 60 c.c. of 30% nitric acid and drying it using a rotary evaporator. was placed in a heat-resistant glass reactor with an inner diameter of 7 mmφ, and the mixture was heated to normal pressure.
Diacetoxybutene 12.2m under 200℃ reaction temperature
mol/hr, nitrogen 600c.c./hr, hydrogen chloride 3.72m
The isomerization reaction was carried out by continuously feeding at a feeding rate of mol/hr. The distribution of isomers after a certain period of time is quantified using gas chromatography, and the results are displayed.
Shown in 1. Comparative Example 1 Example 1 except that hydrogen chloride was not supplied
The reaction was carried out in a similar manner. The distribution of isomers after a certain period of time was determined by gas chromatography, and the results are shown in Table 2. Example 2 0.5 g of a catalyst was prepared by soaking 25 g of crushed coconut shell activated carbon (20 to 60 mesh) in a solution of 4.7 mmol of palladium nitrate dissolved in 60 c.c. of 30% nitric acid and drying it using a rotary evaporator. Inner diameter 7
Prepared in a mmφ heat-resistant glass reactor, normal pressure, 200
℃ reaction temperature, 3,4-diacetoxybutene-1
12.2m mol/hr, nitrogen 600c.c./hr, hydrogen chloride
Continuously supplied at a feeding rate of 3.72m mol/hr,
An isomerization reaction was performed. The distribution of isomers after a certain period of time was determined by gas chromatography, and the results are shown in Table 3. Comparative Example 2 Example 2 except that hydrogen chloride was not supplied
The reaction was carried out in a similar manner. The distribution of isomers after a certain period of time was determined by gas chromatography and the results are shown in Table 4. Example 3 0.6 m mol/hr of hydrogen bromide instead of hydrogen chloride
The reaction was carried out in the same manner as in Example 2, except for supplying at a ratio of . The distribution of isomers after a certain period of time was determined by gas chromatography, and the results are shown in Table 5.

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[Table] Also, the numerical unit of isomer distribution is mol%, and the unit of time is hr.

Claims (1)

[Claims] 1. Mutually reversibly reacting 1,4-diacetoxybutene-2 and 3,4-diacetoxybutene-1 in the gas phase in the presence of a catalyst in which palladium is supported on activated carbon and hydrogen chloride or hydrogen bromide. A method for isomerizing diacetoxybutene, which is characterized by isomerizing diacetoxybutene.