JPS61129144A - Separation of m-cresol - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a raw material of sumithion (an organophosphorus insecticide) easily, by contacting a mixture of cresol isomers with a specific fumaric acid amide, and separating and decomposing the produced complex. CONSTITUTION:A mixture of cresol isomers is made to contact with >=1mol, preferably 2-10mol of N,N,N',N'-tetraisopropylfumaric acid amide based on 1mol of m-cresol, in an organic solvent such as ethyl ether, chloroform, etc. at 10-50 deg.C to effect the formation and precipitation of a complex of m- cresoland said fumaric acid amide. The objective compound can be produced by separating the complex e.g. by decantation, filtration, etc., and decomposing the complex by heating at about 50-300 deg.C under reduced pressure (about 1.0-100mmHg).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to a novel method for separating m-cresol from a mixture of cresol isomers.

Cresol has three isomers, 0-1m-1 and p-unit, and these isomers are commonly used, and there are also applications in which it is used as a mixture of two or more isomers. In some cases, only one isomer is suitable for a particular application. Common uses include disinfectants, preservatives, and raw materials for surfactants. In addition, suitable uses for only 0-cresol include analytical reagents or MCP agents (2-methyl-4-chlorophenoxyacetic acid), which are herbicides, and suitable uses only for m-cresol include: Sumithion [0,0-dimethyl-〇-(3-methyl-4-nitrophenyl) thiophosphate], which is an insecticide, can be mentioned; Examples include raw materials for inhibitors.

[Description of prior art]

Industrial methods for producing cresol include alkali extraction of tar fraction, toluene chlorination hydrolysis, and toluene sulfonation alkali melting.

In any of these methods, cresol is 0-
It is obtained as a mixture of three isomers, 1m-1 and p-unit. Therefore, it is not necessary to separate each isomer if it is applicable to the above-mentioned common uses, but it is necessary to separate each isomer if each isomer is applied to a single use.

By the way, the boiling point of 0-cresol is 191.0'c.

The boiling point of m-cresol is 202.2°C, and the boiling point of p-cresol is 201.9°C. Therefore, 0-cresol can be easily separated by distillation, but
It is impossible to separate a mixture of m-cresol and p-cresol into each isomer component by a simple distillation operation.

Conventionally, a mixture containing three isomers of cresol is separated by fractional distillation to separate O-cresol, which has a low boiling point, as the first distillate.
After sulfonating the remaining m- and p-cresol,
First, a sulfonated product of m-cresol, which is easily decomposed, is decomposed by steam decomposition to separate and obtain m-cresol,
Finally, p-cresol is obtained, which is a complicated operation to separate each isomer component. Moreover, in order to obtain each isomer with high purity, the obtained m-cresol is rectified,
O- and p-cresol need to be recrystallized.

[Requirements of the present invention] In view of these circumstances, the inventors conducted extensive research with the aim of establishing a method that can separate a mixture of cresol isomers with simple operations. As a result, among the three isomers of cresol, only m-cresol
It was discovered that it forms a complex with N, N, N', N'-tetraisopropyl fumaric acid amide and precipitates, so it can be very easily separated from other isomers, leading to the present invention.

That is, the present invention involves contacting a cresol isomer mixture with N,N,N',N'-tetraisopropyl fumaric acid amide in an organic solvent to produce a complex of m-cresol and the fumaric acid amide. The present invention provides an industrially advantageous method for separating m-cresol from a mixture of cresol isomers by precipitating it, separating the complex, and then decomposing the complex.

[Detailed explanation of each requirement]

In this invention, the isomer mixture of cresol is 〇-
It can also be a mixture of three isomers, m- and p-unit, or a mixture of two isomers, m- and p-unit. That is, according to the present invention, m-cresol is first separated from a mixture of three isomers, and then 0-cresol and p-cresol can be separated by distillation if necessary. Further, by first separating 0-cresol from a mixture of three isomers by distillation, and then applying the present invention to a mixture of m- and p-cresol, both can be easily separated. .

As mentioned above, according to the separation method of the present invention, m-cresol and p-cresol, which cannot be separated by a simple distillation operation, can be separated.
m-cresol can be easily separated and recovered from a small amount of cresol (an isomer mixture containing both),
Further, since a mixture containing p-cresol and 0-cresol can be easily separated by a conventional method (distillation operation, etc.), ultimately each isomer of cresol can be easily isolated and recovered.

N,N,N',N''-tetraisopropyl fumaric acid amide in the present invention can be easily synthesized, for example, by reacting fumaric acid chloride and diisopropylamine, and is represented by the following structural formula.

In this invention, the amount of N,N,N',N''-tetraisopropyl fumaric acid amide used is 1 mol or more, preferably 2 mol or more, per 1 mol of m-cresol contained in the cresol isomer mixture. ~10 moles.

The organic solvent used in this invention sufficiently uniformly dissolves each isomer of cresol and N,N,N',N''-tetraisopropyl fumaric acid amide, and also dissolves the 'm-cresol produced in this invention and the A solvent is desired in which the solubility of the complex is low so that the complex with fumaric acid amide precipitates. Specific examples of such organic solvents include petroleum ether, ethyl ether, chloroform, glycol, benzene, hexane, acetonitrile, ethyl acetate, and mixtures thereof.

These organic solvents are 2 to 20 m
It is enough if it is used about 1 time.

The contact (reaction) between the cresol isomer mixture and the fumaric acid amide is usually carried out at a temperature of 10 to 50°C and a reaction time of 1 to 20°C.
It is best to do this for about an hour. Through this contacting operation, among the isomers of cresol, in particular, only m-cresol forms a complex with the fumaric acid amide, and is precipitated from the solution in which each raw material component was initially dissolved. The complex precipitated in this way can be easily separated by operations such as filtration and decantation, and can be easily separated under reduced pressure (approximately 1.0 to 1
00? +1-snow), the complex is heated at about 50 to 300°
By heating to a temperature of C, m-cresol can be separated and obtained.

After the complex of m-cresol and the fumaric acid amide is precipitated, the remaining liquid from which the precipitate is separated is subjected to a distillation operation to separate other isomers of cresol, respectively.
can be obtained.

In addition, in this invention, the N,N,N',N'-tetraisopropyl fumaric acid amide recovered during the separation and acquisition of m-cresol can be repeatedly used in the above-mentioned separation operation.

〔Example〕

Next, examples of this invention will be described.

Example 1 Cresol isomer mixture (composition is m-cresol;
54.11 mol%, p-cresol; 27°27 mol%
, and 2,4- and 2,5-xylenol; 14,4
1 mol%) 2.5 g and N, N, N', N
'-tetraisopropyl fumaric acid amide 6, Og,
The solution was dissolved in 30 ml of petroleum ether and allowed to stand at room temperature for 12 hours. 3.0 g of crystals of a complex consisting of one molecule of sult, N, N, N', N'-tetraisopropyl fumaric acid amide and one molecule of m-cresol were precipitated. The crystals were separated by filtration, and 1.0 g of N, N, N''N l-tetraisopropyl fumaric acid amide was added to the filtrate and left to stand for an additional 12 hours to obtain an additional 1.0 g of crystals of the same complex as above. The obtained crystals were combined and recrystallized once in 20 ml of petroleum ether, and the crystals obtained by filtration were dried to give colorless needle-like crystals (melting point: 78-8
0°C) was obtained. When 3.3 g of crystals of this complex was heated to about 200° C. at about 30 Hg, 0.91 g of m-cresol was distilled out.

Claims (1)

[Claims] A mixture of cresol isomers is prepared in an organic solvent by N, N,
It is characterized by contacting with N',N'-tetraisopropyl fumaric acid amide to generate and precipitate a complex of m-cresol and the fumaric acid amide, separating the complex, and then decomposing the complex. Separation method of m-cresol.