JPS6029366B2 - Production method of phenol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to 1,5,5-trimethylcyclohexene-3-
This invention relates to a method for producing 3,5-xylenol from on (isophorone).

It is known from British Patent No. 584,256 that isophorone can be converted to 3,5-xylenol by heating it at a temperature of 668-67,600°C.

However, the product yield is relatively low (39%). It is also known to use various solid catalysts to improve yields. Examples of such catalysts include British Patent No.
88099 and chromium oxide (m) as described in British Patent No. 1197803.
) There is a copper monoxide (1) mixture. Such solid catalysts have the disadvantage that carbon deposits are formed on the catalyst during the conversion reaction. This reduces catalyst activity and requires intermittent reaction termination to regenerate the catalyst. It has now been found that isophorone can be converted to 3,5-xylenol in good yields using certain homogeneous catalysts.

Therefore, the present invention provides a process for producing 3,5-xylenol in which isophorone is heated to a temperature of 450 oo to 650 oo with a halogen selected from chlorine, bromine and iodine, or a halogen containing such a halogen and having 1 to 6 carbon atoms. Provided is a production method characterized by heating in the presence of a substituted saturated or unsaturated aliphatic compound or a halogenated phenyl containing such a halogen.

The aliphatic compound and the phenyl halide may contain any of chlorine, bromine and iodine, but are preferably iodine-containing compounds.

Examples of aliphatic compounds include haloalkanes such as methyl iodide, n-butyl bromide and carbon tetrachloride, and allyl halides such as allyl bromide. An example of halogenated phenyl is phenyl iodide. The amount of catalyst may be from 0.01 to 20%w, preferably from 0.1 to 5.0%w, based on the weight of isophorone. The treatment is preferably carried out at a temperature of 550-650qC.

Conveniently the pressure is atmospheric, although the treatment may be carried out at reduced or superatmospheric pressure. In one embodiment, the treatment is carried out continuously by passing isophorone and catalyst through a heated tube reactor.

Isophorone and the catalyst may also be mixed with an inert gas such as nitrogen or an alkane to improve the selectivity of the process and/or to improve heat transfer within the reactor. Under certain conditions it may be advisable to irradiate the reaction mixture with ultraviolet light.

3,5-xylenol may be recovered from the reaction mixture and purified by any suitable method, for example by distillation.

For economic reasons, it may also be desirable to include a separate recovery step for the halogen or halogen-containing organic compound in the process. The invention is further illustrated in the following example.

Examples 1-12 The reactor consisted of a 320 mm long and 1 mm diameter stainless steel tube with 5 mm diameter thermocouples along its length.

The tube was surrounded by an electrically heated oven. The catalyst was dissolved in isophorone and the mixture was passed through a heated tube at constant space velocity. The product was dissolved in acetone and analyzed by GLC. The results of various experiments were as shown in the table below.

The product yields from the numerous experiments were combined (548.6 in total) and distilled under reduced pressure.

3,5-xylenol with a purity greater than 99%,
Obtained with a yield of 85.4%, b・p・9 with 1 side Hg
It was 0195Q0.

Table * The reaction mixture was diluted with nitrogen; molar ratio N2:isophorone = 1:4o** used as a solution in benzene (9.3 g Br2 per 100 ml 06 days).

Claims (1)

[Claims] 1. In the method for producing 3,5-xylenol, isophorone is heated to a temperature of 450°C to 650°C and a halogen selected from chlorine, bromine and iodine, or containing such a halogen and containing 1 to 6 carbon atoms is added. A production method characterized by heating in the presence of a saturated or unsaturated aliphatic compound substituted with a halogen atom, or a halogenated phenyl containing such a halogen. 2. The production method according to claim 1, wherein the aliphatic compound is a haloalkane or an allyl halide. 3. The production method according to claim 1 or 2, wherein the aliphatic compound or phenyl halide is an iodine-containing compound. 4. The production method according to claim 3, wherein the aliphatic compound or phenyl halide is methyl iodide or phenyl iodide. 5. Process according to any of claims 1-4, wherein the amount of catalyst used is 0.1-5%w based on the weight of isophorone. 6. The manufacturing method according to any one of claims 1 to 5, wherein the temperature is 550°C to 650°C.