JPS6039251B2 - Separation method of metacresol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining meta-cresol from mixed cresols.

The so-called mixed cresol can be obtained by alkali extraction and subsequent neutralization from 200 to 220 kg of tar, low-temperature carbonized tar, or by the so-called cymene method, in which cymene is oxidized and then decomposed.

This mixed cresol is composed of isomers such as oxocresol, metacresol and paracresol. When obtaining meta-cresol from mixed cresol, ortho-cresol can be separated by ordinary distillation because it has a relatively large boiling point difference with meta-cresol and para-cresol, but para-cresol has a boiling point difference of about 0. It is difficult to separate para-cresol and meta-cresol by normal distillation because they are extremely small. Therefore, various methods have been proposed to separate metacresol from a mixed cresol, particularly a mixture of para-cresol and metacresol, including the following methods.

A. Derivative method B. Co-brood distillation method C. Molecular compound formation method All of these methods have advantages and disadvantages, and it cannot be said that which one is the best, but the method of forming and separating molecular compounds is relatively easy compared to other methods. It has the advantage that highly pure metacresol can be easily obtained.

However, there is a method using a molecular compound of urea and metacresol (hereinafter abbreviated as the urea method).

) and the method via a molecular compound of phenol and metacresol (hereinafter referred to as the phenol method) require a reaction at a temperature of 0°C or lower when producing each molecular compound, and therefore the equipment and operations are somewhat complicated. It has the disadvantage of being complicated. Furthermore, a method characterized by decomposing molecular compounds with ethers has been proposed as an improved method of the conventional urea method (Tsubaki Publication No. 48-10145).
Furthermore, the decomposition rate is insufficient, and when pure metacresol is obtained by distillation from an ether solution containing metacresol after decomposition, a trace amount of urea that enters the distillation system causes thermal decomposition, resulting in metacresol. It has drawbacks such as significantly worsening the hue of cresol. On the other hand, a method using a molecular compound of sodium acetate and metacresol is also known, and in this method, when the molecular compound is decomposed into metacresol and sodium acetate, a heating method or a method of adding water is adopted. , when heating, the yield decreases due to the formation of tar due to deterioration of meta-cresol, and when adding water, a huge amount of energy is required to recover the sodium acetate dissolved in water. Sodium acetate cannot be reused unless it is dehydrated until it essentially contains no water, that is, until it becomes an anhydrous salt, and this requires a huge amount of energy.

Therefore, the object of the present invention is to use sodium acetate and metacresol.
The object of the present invention is to solve the above-mentioned drawbacks in the method for obtaining meta-cresol by decomposing a molecular compound with metal. The present inventor has developed a molecular compound of sodium acetate and metacresol.
We have discovered that when alcohols, ketones, ethers, or mixtures thereof are added to the molecular compound, the molecular compound decomposes extremely rapidly and quantitatively into metacresol and sodium acetate even at room temperature, and therefore these compounds If sodium acetate is used as a decomposition agent, there is no need for heating, there is no reduction in yield due to tar formation, and no water is used, making the recovery of sodium acetate extremely easy, eliminating all of the above disadvantages, and Taking advantage of the rapid decomposition rate, a rational manufacturing process is possible in which various steps such as separation and decomposition of the molecular compound and separation of sodium acetate and meta-cresol can be performed in the same apparatus, which has led to the completion of the present invention. Ta. That is, the present invention involves reacting mixed cresol with sodium acetate to generate a molecular compound of metacresol and sodium acetate, separating the molecular compound, and then decomposing the molecular compound into metacresol and sodium acetate. The method for separating metacresol is characterized by adding alcohols, ketones, phenols, or a mixture thereof to the molecular compound to decompose metacresol and sodium acetate.

The molecular compound of metacresol and sodium acetate referred to in the present invention can be easily obtained by a known method.

For example, it can be obtained by dissolving the mixed cresol in an aliphatic hydrocarbon solvent such as hexane, heptane or petroleum ether, adding sodium acetate, stirring at room temperature for several hours, and then filtering in a furnace. The sodium acetate used here does not contain water of crystallization, that is, it is an anhydrous salt. The molecular compound of metacresol and sodium acetate obtained in this way can be converted into metacresol and sodium acetate extremely quickly and quantitatively even at room temperature by adding alcohols, ketones, ethers, or a mixture thereof as a decomposition agent. It can be decomposed into

Therefore, there is no need for heating and no tar is generated. The alcohols and ketones used as decomposition agents in the present invention are represented by the structural formulas [1] and m], and the ethers are represented by the structural formula [m], dioxane or tetrahydrocarbon. It's a franc.

Here, R,, R2 and R3 are alkyl groups having 1 to 5 carbon atoms, respectively, and R4 and R5 are alkyl groups having 2 to 5 carbon atoms.

Specifically, methyl alcohol, ethyl alcohol, and alcohol.

Lopy'rea/lecole, isopropyl alcohol, n-
butyl alcohol, sec-butyl alcohol, rt
- Alcohols such as butyl alcohol, n-amyl alcohol, isoamyl alcohol, neobentyl alcohol, diethyl carbinol, 2-pentanol, methyl isopropyl carbinol, tert-amyl alcohol, acetone, diethyl ketone, n-propyl ketone, diisof. Lopyl ketone, dibutyl ketone, diisobutyl ketone, di-sec-butyl ketone,
Di-tert-butyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl-sec-butyl ketone,
Ketones such as methyl tert-butyl ketone, methyl isobutyl ketone, methyl n-butyl ketone, ethyl butyl ketone, ethyl n-propyl ether, ethyl n-butyl ether, ethyl isobutyl ether, ethyl sec-butyl ether, ethyl tert-butyl ether, ethyl n-amyl ether, ethyl rt-amyl ether, ethyl neobentyl ether, n-propyl isobutyl ether, isopropyl n-butyl ether, n-propylte-butyl ether, di-n
Ethers such as -butyl ether, n-butyl ether, and n-butyl ether can be mentioned. Preferred are methyl alcohol, ethyl alcohol, acetone, methyl ethyl ketone, and methyl isobutyl ketone. Further, when adding the decomposing agent, an aliphatic hydrocarbon solvent such as hexane, heptane or petroleum ether, or an aromatic hydrocarbon solvent such as benzene, toluene or benzene may be co-present.

The amount of the decomposing agent added to the molecular compound is from 10 to 500 parts by weight, preferably from 30 to 10 parts by weight, per 100 parts by weight of the molecular compound.

The rate of decomposition of the molecular compound by the decomposer is extremely slow and quantitative at room temperature, so if the decomposition reaction is carried out in a reactor, it is sufficient to turn on the light for about 1 to 5 minutes after adding the decomposer. be. Thus, the molecular compound is decomposed into metacresol and sodium acetate by the addition of a decomposer, but at the same time as the decomposition, metacresol dissolves in the decomposer or the solvent phase containing the decomposer, and the sodium acetate is almost dissolved in the solvent phase. It remains as a solid phase.

Therefore, a solution containing metacresol can be obtained by filtration. Moreover, a more rational process is possible by taking advantage of the high decomposition rate.

That is, the steps of separation and decomposition of molecular compounds and separation of methanol and sodium acetate can be performed in one furnace. In other words, after reacting mixed cresol with sodium acetate to generate a molecular compound of meta-cresol and sodium acetate, the wet cake of the molecular compound in the furnace obtained by furnace heating was subsequently heated in the same furnace. By washing with a decomposer or a solvent containing a decomposer, it is possible to decompose metacresol and sodium acetate, and at the same time perform a furnace filtration operation to separate the solution containing metacresol from sodium acetate. . By subjecting the thus obtained metacresol-containing solution to conventional distillation, pure metacresol with high purity and excellent hue can be obtained. Sodium acetate can be obtained by decomposing the molecular compound and then drying what remains as a solid phase after filtration by a simple drying method, for example in a nitrogen stream, or by treating mixed cresol with sodium acetate to form meta-cresol. It can be used again by washing with the solvent used in producing the molecular compound of sodium acetate, for example an aliphatic hydrocarbon solvent such as hexane, hebutane or petroleum ether, to remove the decomposing agent. Therefore, very little energy is required to bring the sodium acetate into a state where it can be reused. With the completion of the invention detailed above,
The drawbacks of the conventional separation method of metacresol from mixed cresol via molecular compounding of metacresol and sodium acetate could be overcome.

That is, when decomposing the molecular compound, there is no need to heat, so there is no decrease in yield due to tar formation, and because an organic solvent that does not dissolve sodium acetate is used instead of using water as a decomposing agent, sodium acetate It has become extremely easy to collect and reuse the materials. Furthermore, a rational method can be developed by taking advantage of the fact that the decomposition rate of the molecular compound by the decomposition agent of the present invention is slow. . It became possible to form a set. Therefore, a method for producing highly pure meta-cresol from mixed cresol at a low cost can be established, and the present invention has great industrial value.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A 500 mm glass flask equipped with a distillation device and a thermometer was charged with 38.0 mm of mixed cresol (63% meta-cresol, 37% vala-cresol), and then 200 mm of n-heptane was added to make the mixed cresol. After dissolving the mixture, 60.0 g of sodium acetate (anhydrous salt) was added and the mixture was incubated at room temperature for 2 hours, followed by a suction oven using a glass filter.

Furthermore, the obtained wet cake was diluted with 200% of n-hebutane [
Washed with. After completion of the above operations, the amount of cresols contained in the recovered n-hebutane solution was 18.5%, and the amounts of meta-cresol and para-cresol were 25% and 75%, respectively. The obtained wet cake (total amount of cresols: 19.
5 evening) Meta-cresol 99.5%, Para-cresol 0.
5%) was placed in a 500ml flask equipped with a total volume loss pestle, 200ml of n-hebutane was added to make a suspension, 30% of acetone was added, and the mixture was allowed to stand at room temperature for 4 minutes. Next, the solid phase was separated into a solid phase and a mother liquor using a glass filter.
000 for 30 minutes, 58.0 minutes (recovery rate 97%) of sodium acetate (anhydrous salt) was obtained. No tar formation was observed. When the obtained mother liquor was subjected to conventional fractional distillation, metacresol with a purity of 99.5% was obtained.
A yield of 75% was obtained. Examples 2 to 5 The same operation as in Example 1 was carried out except that methyl alcohol, ethyl alcohol, methyl ethyl ketone, and dioxane were used instead of acetone as a decomposing agent, and the yield and purity of the finally obtained metacresol are shown in the table. Indicated.

Table Example 6 10 A mixture of sodium acetate and a molecular compound consisting of a ratio of 3% by weight of metacresol and 7% by weight of sodium acetate (anhydrous salt) was placed in the hawk-layered reactor (made of stainless steel). The suspension was suspended in 5 g of n-hebutane, 0.5 g of acetone was added, and the mixture was stirred at room temperature for 4 minutes.

Claims (1)

[Scope of Claims] 1. By reacting mixed cresol with sodium acetate to generate a molecular compound of metacresol and sodium acetate, separating the molecular compound, and then decomposing the molecular compound into metacresol and sodium acetate. A method for separating metacresol, which comprises adding alcohols, ketones, ethers, or mixtures thereof to the molecular compound to decompose it into metacresol and sodium acetate. 2. The method according to claim 1, characterized in that methyl alcohol or ethyl alcohol is used as the alcohol. 3. The method according to claim 1, characterized in that acetone, methyl ethyl ketone, or methyl isobutyl ketone is used as the ketone. 4. The method according to claim 1, wherein the molecular compound is decomposed without heating.