JPS59219247A - Preparation of 4-hydroxy-2,4,6-trimethyl-2,5- cyclohexadien-1-one - Google Patents

Abstract

PURPOSE:To produce the titled compound in high yield, by separating and recoivering 2,6-xylenol from the liquid produced be the reaction of phenol with methanol, removing tarry substance from the residual liquid, and successively carrying out the oxidation of the liquid. CONSTITUTION:2,6-Xylenol is separated and recovered e.g. by distillation, from the liquid obtained by the reaction of phenol and methanol, and the resultant residual liquid containing 2,4,6-trimethyl-phenol is distilled to remove the tarry substance having a boiling point of >=270 deg.C from the residual liquid (to <=10wt%, especially <3wt%). The objective compound can be prepared by oxidizing the distillate by contacting with O2 or O2-containing gas, or by adding hydrogen peroxide dropwise to the distillate. The obtained compound can be converted easily to 2,3,6-trimethylhydroquinone useful as an antioxidant and polymerization inhibitor, by the rearrangement reaction in the presence of a base.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides 2,6
-2,4. contained in the reaction product liquid containing xylenol.
The present invention relates to a method for producing 4-hydroxy-2,4,6-1-limethyl-2,5-cyclohexadien-1-one in high yield by oxidizing 6-1-limethylphenol.

4-Hydroxy-2,4,6-drimethyl-2,5-cyclohexadien-1-one easily undergoes a rearrangement reaction in the presence of a base to produce 2,3,6-1-limethylhydroquinone. This 2,3°6-drimethylhydroquinone is not only used as an antioxidant and polymerization inhibitor, but is also very useful as a raw material for producing vitamin E.

Conventionally, 4-hydroxy-2,4,6-)rimethyl At-2
, 5-cyclohexadien-1-one has been proposed. For example, a method of oxidizing 2.4.6-drimethylphenol with molecular oxygen in an organic solvent using a sarcomine catalyst ( For example, in an aqueous alkaline solution, 2,
Examples include a method of oxidizing 4,6-dolimethylphenol with molecular oxygen (for example, JP-A-50-4044). However, in either method, raw material No. 2,
4. e-) Limethylphenol needs to be of high purity and requires expensive reagents, resulting in high production costs and cannot be said to be an economically advantageous production method. .

The present inventors have discovered that these conventional 4-hydroxy-2,4
,6-drimethyl-2,5-cyclohexadiene-1-
In order to overcome the drawbacks of the production method of 2,4,6-xylenol contained in the residual liquid, 2,6-xylenol was separated and recovered from the reaction product liquid containing 2,6-xylenol produced from phenol and methanol 4-Hydroxy-2,4,6-)rifthyl-2,5- using 1-limethylphenol
As a result of intensive study on a method for obtaining cyclohexadien-1-one, we found that by removing tar-like substances contained in the residual liquid in advance, 4-hydroxy-2,4,6
-) It was discovered that the yield of riftyl-2,5-cyclohexadien-1-one was dramatically improved, and based on this finding, the present invention was completed.

That is, in the present invention, after separating and recovering 2,6-xylenol from a 2,6-xylenol reaction product liquid obtained from phenol and methanol, ? , oxidize the residual liquid containing 4.6-1-limethylphenol to produce 4-hydroxy-2,
4,6-1-dimethyl-2,5-cyclohexadiene-
4-Hydroxy-2,4,6-1-rifthyl-2,5-cyclo, which is characterized in that, in producing 1-one, tar-like substances contained in the residual liquid are removed in advance. A method for producing hexadien-1-one is provided.

The 2,4.6-1-limethylphenol solution used in the present invention is a 2,4.6-1-limethylphenol solution prepared from phenol and methanol.
, 2,6-xylenol is separated and recovered from the reaction product solution containing 6-xylenol by distillation, etc.
Any residual liquid containing by-products may be used. 2,6-xylenol is usually produced from phenol and methanol in the presence of a catalyst;
．． 3. In addition to 6-l.trimethylphenol, a tar-like substance is produced as a by-product. Here, the tar-like substance is a general term for substances with a boiling point of 270° C. or higher that are by-produced when 2,6-xylenol is synthesized from such phenol and methanol.

In the method of the present invention, the content of 2.4.6-1-limethylphenol in the raw material 2,4.6-1-limethylphenol solution is not particularly limited, but is preferably 50% by weight or more, More preferably, it is 80% by weight or more.

Further, it is not necessarily necessary to remove the tar-like substance, and its content is preferably 10% by weight or less, more preferably 3% by weight or less. If this content (i) exceeds 10% by weight, not only will the entire oxidation reaction solution be colored blackish brown, but also 4-hydroxy-2,4,6-1-rifthyl-2
, 5-cyclohexadien-1-one yield drops significantly. Also, if it is less than 3% by weight, pure 2,4
, no significant difference was observed from the case of using 6-1-limethylphenol. Tar-like material removal operations are typically
Implemented by Akira.

In the present invention, the fermentation reaction can be carried out in the presence or absence of a liquid medium, but is preferably carried out in a liquid medium. Examples of this liquid medium include water, methanol, ethanol, n-propanol,
-Propertool, n-butanol, i-butanol, L
-butanol, carbon tetrachloride, chloroform, acetonitrile, dimethylacetamide, dimethylformamide,
Instead of acetone, methane, cyclohexane, benzene, toluene, etc., solutions of water and the above organic liquid medium may also be used. The solubilization reaction can be carried out, for example, by contacting 2,4,6-drimethylphenol dissolved or suspended in a liquid medium with molecular oxygen or a molecular oxygen-containing gas; , 4.6
- It is carried out by a method such as dropping hydrogen peroxide into dolimethylphenol. In this case, molecular oxygen or molecular
For example, the shape of the scum containing slag is from normal pressure to 80 Kg/
cm'G range, and hydrogen peroxide is used, for example, as a hydrogen peroxide solution of about 3% by weight.

This oxidation reaction is preferably carried out under alkaline conditions. Although there are no particular limitations on the method for adjusting the alkaline conditions, it is preferable to adjust the conditions by adding an alkali metal or a compound thereof, or an alkaline earth metal or a compound thereof.

The temperature of the solubilization reaction is set to the target 4-hydroxy-2,4,6
Although -drimethyl-2,5-cyclohexadien-1-one is produced, any temperature at which it does not decompose or change is sufficient, but a temperature in the range of 0 to 80°C is usually preferred. At temperatures below 0°C, the reaction does not substantially proceed, and at temperatures above 80°C, the selectivity of the target compound decreases. Also, the reaction time is 10
A range of minutes to 5 hours is preferred.

According to the present invention, there is no need to use high-purity turtle raw materials, and 2.
4-Hydroxy-2,4,6-1-limethyl-2.5-cyclohexadien-1-one can be produced in high yield from the residual liquid of 6-xylenol production.

Next, the present invention will be explained in more detail based on examples.

In addition, the compositional analysis of the reaction product was performed by Cass chromatography. Moreover, parts in each example refer to parts by weight.

Examples 1 to 3 and Comparative Examples g0 having a gas introduction part and equipped with a temperature controller 1 and a stirrer
A 2,6-xylenol production residual liquid (2,4) having the composition shown in the table below and containing 100 parts of water and 3.5 parts of sodium hydroxide in a 0 ml stainless steel autoclave and containing tar-like substances in advance at 10% by weight or less.

Add 15 parts of 6-drimethylphenol solution and add 30
An oxygen pressure of Kg/cm'G was applied, the internal temperature was maintained at 30'C, and the reaction was carried out for 4.5 hours with vigorous stirring. After the reaction was completed, the reaction product was taken out and analyzed, and the results are shown in Example 1.
-3 in the following table. In the table, HTCD represents 4-hydroxy-2,4,6-)-samethyl-2,5-cyclohexadien-1-one, and TMP represents trimethylphenol.

Claims (1)

[Claims] After separating and recovering 2,6-xylenol from the 2゜6-xylenol reaction product liquid obtained from phenol and methanol, the residual liquid containing 2,4゜6-dolimethylphenol is oxidized to produce 4-hydroxy-2. , 4,6-)Samethyl-2,5-cyclohexadien-1-one is produced by removing tar-like substances contained in the residual liquid in advance. 2,4,6-
Dorimethi) Iy -2,5-cyclohexadiene-1-
On manufacturing method.