JPS598248B2 - Method for producing 1,4-cyclohexanedione - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 1,4-cyclohexanedione.

More specifically, the present invention relates to a method for producing 1,4-cyclohexanedione by gas phase dehydrogenation of 1,4-cyclohexanediol. 1,4-cyclohexanedione has recently been
7, 7, 8 attracting attention as raw materials for the synthesis of organic semiconductors
- It is an extremely important compound industrially as a raw material for the production of 8-tetracyanoquinodimethane, and an effective method for its production has not yet been established.

The present inventors have conducted intensive studies on a method for producing 1,4-cyclohexanedione through a dehydrogenation reaction of 1,4-cyclohexanediol, and as a result, have found a method for producing 1,4-cyclohexanedione with good yield, and have arrived at the present invention. That is, the present invention
It is characterized by contacting 1,4-cyclohexanediol with a dehydrogenation catalyst selected from copper oxide, copper oxide-partial zinc oxide, copper chromium monoxide, and copper manganese monoxide in the presence of hydroquinone in the gas phase. This is a method for producing 1,4-cyclohexanedione.

According to the present invention, it has been revealed that when hydroquinone is added to the dehydrogenation reaction of 1,4-cyclohexanediol, the yield of 1,4-cyclohexanedione is greatly improved.

1,4-Cyclohexanediol used as a raw material can be produced by hydrogenating hydroquinone or p-benzoquinone, but is generally produced by hydrogenating hydroquinone in an aqueous solvent.

When producing 1,4-cyclohexanediol by such a method, the reaction is stopped with - portion of hydroquinone remaining, and the hydrogenation catalyst is removed by filtration.
The reaction mixture can be used as it is as a raw material for the dehydrogenation reaction without isolating the cyclohexanediol.

In the dehydrogenation reaction of 1,4-cyclohexanediol according to the present invention, a dehydrogenation catalyst selected from copper oxide, copper oxide-partial zinc oxide, copper oxide chromium monoxide, and copper oxide manganese monoxide is used.

These catalysts can be used alone, but they can also be supported on a carrier such as activated alumina, silica alumina, silica gel, activated carbon or diatomaceous earth. Further, in this reaction, the raw material 1,4-cyclohexanediol can be supplied diluted with a diluent such as water, benzene, or cyclohexane, or an inert gas such as nitrogen, helium, or argon.

Among these diluents, water is particularly preferred. The reaction is usually carried out at 100 to 400°C, especially 200 to 350°C.
Preferably, it is carried out at ℃. The contact time with the catalyst varies depending on the reaction temperature, but is usually in the range of 6 minutes to 0.4 seconds. The amount of hydroquinone added to 1,4-cyclohexanediol is usually 0.1 to 40 mol%,
Particularly preferred is 0.5 to 20 mol%.

Hydroquinone added to the dehydrogenation reaction in the method of the present invention is separated from the reaction product by a conventional method after the reaction and reused. Next, the present invention will be specifically explained with reference to Examples.

Examples 1 to 3, Comparative Example 1 Quartz gas phase reaction tube (inner diameter 28 m
m, length 550mm, spherical α fired at 1200℃
- Filled with alumina (diameter 57n030y, filled with 60y of copper oxide zinc monoxide catalyst (60% copper oxide and 40% zinc oxide) fired at 400°C, and then filled with 150y of the above alumina.

This gas phase reaction tube was kept at 260°C in an electric furnace, and the GHSV
Under reaction conditions of 5OOhr-1, raw materials consisting of 5 mol% of 1,4-cyclohexanediol, 45 mol% of water, hydroquinone at the concentration shown in Table 1 relative to 1,4-cyclohexanediol, and nitrogen were introduced. It operated continuously for 8 hours.

The amount of 1,4-cyclohexanedione in the effluent was determined by gas chromatography, and the yield based on the supplied 1,4-cyclohexanediol is shown in Table 1Z. The results in Table 1 show that the addition of hydroquinone improves the yield of 1,4-cyclohexanedione.

Examples 4 to 5, Comparative Examples 2 to 3 In Example 1, the catalyst shown in Table 2 was used instead of the copper oxide zinc monoxide catalyst, and the catalyst shown in Table 2 was used for 1,4-cyclohexanediol. A similar reaction was carried out by adding the indicated amount of hydroquinone, and the following results were obtained.

From the results in Table 2, it can be seen that the yield of 1,4-cyclohexanedione is improved by adding hydroquinone even in the catalyst system of copper oxide copper monochromite or copper oxide manganese monoxide.

Example 6, Comparative Example 4 Using a CuO catalyst as a catalyst, 1.
4-cyclohexanediol 5 mol%, water 85 mol%,
GHSV5OOhr-1, 26 raw material containing 10 mol% nitrogen
The reaction was carried out at 0°C.

Claims (1)

[Claims] 1. In the presence of hydroquinone, 1,4-cyclohexanediol is brought into contact with a dehydrogenation catalyst selected from copper oxide, copper oxide-zinc oxide, copper oxide-chromium oxide, and copper oxide-manganese oxide in the gas phase. A method for producing 1,4-cyclohexanedione.