CN1223565C

CN1223565C - Preparation process of meta-cresol

Info

Publication number: CN1223565C
Application number: CN 03112639
Authority: CN
Inventors: 唐师法
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-01-06
Filing date: 2003-01-06
Publication date: 2005-10-19
Anticipated expiration: 2023-01-06
Also published as: CN1515531A

Abstract

The present invention relates to a preparation process of a chemical reagent, particularly to a preparation process of m-cresol which can be used in the industries of pesticides, dye, perfume, resin, plasticizing agents, motion picture films, antioxidants, reagents, etc. The process comprises the flows of salt formation, diazotization, hydrolysis, neutralization and water washing. Main raw material and auxiliary raw material used in production are both sold in China at stable price with quality completely meeting users' requirements. The process has the advantages of little investment, low cost and high benefit; particularly, sulfate as the auxiliary product can be recycled with no three-waste pollution; various technical indices of products can reach and exceed production indices of fellow industry at home and abroad, and can completely meet various requirements through users' use.

Description

Process for preparing m-cresol

Technical Field

The present invention relates to a preparation process of chemical reagent, in particular, it is a preparation process of m-cresol which can be used in the industries of pesticide, dye, perfume, resin, plasticizer, cinefilm, antioxidant and reagent, etc..

Background

M-cresol, chemical name 3-hydroxy toluene, also known as m-methyl phenol, hydroxy toluene, 1-hydroxy-3-toluene, m-distilled wood oilAcid, formula C₇H₈O, a colorless to pale yellow flammable liquid with a phenolic odor, dissolves in about 40 times the amount of water, in caustic and in common organic solvents. Relative density (d)₄ ²⁰)1.034, melting point 11.5 ℃, boiling point 202.8 ℃, flash point 86.1 ℃, self-ignition point 559 ℃, refractive index (n)_D ²⁰)1.5438. The metacresol can be used in the industries of pesticides, dyes, spices, resins, plasticizers, cinematographic films, antioxidants, reagents and the like. The method is mainly used for producing and manufacturing more than 20 chemical raw materials and products such as Sutianwei, fenthion, tinea pedis powder, an antioxidant CA, muskiness, tribromocresol, 4-nitro m-cresol, 3-phenoxytoluene, m-methyl diphenyl ether, m-methyl diphenylaldehyde, calcium cresol sulfonate, disperse yellow SE-5R, chlorocresol m-cresol, 2-chloro-5-cresol, 4-chloro-3-cresol, m-hydroxybenzaldehyde and the like. At present, they are attracting attention particularly in the synthesis of pyrethroids, trimethylhydroquinone which is an intermediate of vitamin E, flavor L-menthol, and coloring materials for facsimile copy paper. At present, the preparation process of m-cresol mainly comprises a toluene method, an o-xylene method, a phenol method and a tar crude distillation method. The preparation process comprises the following steps:

(1) toluene sulfonation alkali fusion process

Toluene and sulfuric acid (98%) are reacted (at the temperature of 100-: 3.1% of phenol, 37.4% of p-cresol, 4.7% of o-cresol and 54.8% of m-cresol. The reaction formula is as follows:

the m-cresol and p-cresol obtained by the reaction are fumigated by a high-efficiency distillation tower, and narrow fraction at the temperature of 201-208 ℃ is cut out, so that a mixture of the m-cresol and the p-cresol is obtained; diluting the material with benzene, adding urea, reacting at-10 deg.c for 1 hr, centrifugal filtering, washing twice with-10 deg.c benzene or toluene to obtain white solid m-cresol-urea complex. Hydrolyzing the complex with toluene at 15-80 deg.C, collecting the upper liquid layer, distilling off toluene and water in a rectifying tower at normal pressure, and cutting at vacuum degree of 0.1Mpa to obtain 91-104 deg.C fraction, i.e. m-cresol with content of more than 95%. The method is the earliest industrialized method, the process route is mature, and the method is adopted for production in early foreign countries. However, the method consumes a large amount of acid and alkali, so that the amount of three wastes is large, equipment is seriously corroded, and solid materials are required to be treated for many times in the process, so that the continuous production is difficult and the quality is poor.

(2) Isopropyl toluene process

Toluene is used as raw material, under the existence of catalyst, propylene is used for alkylation reaction, and then the product is obtained by oxidation and acidolysis. The main reaction formula is as follows:

① alkylation

The alkylation uses aluminium trioxide as catalyst (1% -2%), reaction temperature is 85-115%, and propylene/toluene ratio is 0.4-0.6(mol ratio). Under the condition, the meta isomer with higher yield can be obtained.

② oxidation

The oxidant used for the oxidation of the isopropyltoluene is air, pure oxygen or hydrogen peroxide. Generally, the air oxidation is economical, the oxidation reaction is carried out in the presence of an initiator (benzoyl peroxide or azobisisobutyronitrile), the addition amount is about 1 percent of the weight of the isopropyl toluene, the reaction temperature is 138-140 ℃, the reaction time is 130-150min, the ventilation amount is 5 percent excess according to the theory, the PH of the reaction solution is controlled to be about 5, the oxidation depth is controlled to be 15 percent, and the total isopropyl toluene hydroperoxide under the condition is about 85-90 percent.

③ decomposition

Isopropyl toluene hydroperoxide decomposes in the presence of sulfuric acid to cresol and acetone. The mixed cresol synthesized by the method has approximate ratio of m-isomer to p-isomer of 6: 4. The composition of the decomposed solution after acid decomposition is approximately: 34.2 percent of acetone, 30.7 percent of m-cresol and p-cresol, 6.9 percent of isopropyl toluene, 3.9 percent of a-methyl styrene and 4.4 percent of peroxide.

④ separating and refining

The boiling point difference between o-cresol and m-cresol and p-cresol is large, and the o-cresol and the m-cresol and the p-cresol can be separated by selecting proper equipment, but the m-cresol and the p-cresol have very close boiling points and cannot be separated by adopting a fractionation method, and a good effect can be obtained by adopting an isobutene alkylation method. The process comprises the following steps: alkylating the mixed cresol with isobutene in the presence of a catalyst to obtain a mixture of di-tert-butyl m-cresol and di-tert-butyl p-cresol.

The resultant tert-butylated cresols are complex mixtures which, in addition to mono-tert-butylcresol isomers and di-tert-butylisomers, contain unreacted polymers of cresol and isobutene, which can be separated by distillation on account of their difference in boiling point. The separated 4, 6-di-tert-butyl-m-cresol is heated to 202 ℃ in the presence of a catalyst, and can be decomposed into m-cresol and isobutene by dealkylation, the content of the obtained product m-cresol can reach more than 98%, and the recovery rate can reach about 95%. The recovery rate of isobutene is above 95%, and the isobutene can be recycled. The method can be used for separating m-cresol and co-producing 2, 6-di-tert-butyl-p-cresol antioxidant.

(3) Ortho-xylene oxidation process

O-xylene is oxidized by air under the catalysis of cobalt naphthenate to obtain o-methylbenzoic acid, and then the o-methylbenzoic acid is subjected to oxidative decarboxylation conversion by using copper oxide and magnesium oxide as catalysts to obtain m-cresol.

The crude phenol obtained by the method is refined by a packed tower, the content of m-cresol reaches more than 95 percent, and the refining yield reaches 92 percent.

(4) Phenol process

The phenol method is used for producing m-cresol, and the main raw materials are phenol and methanol.

(5) Crude distillation of tar

Mainly uses the byproduct tar crude phenol in coking as raw material to make multiple distillations so as to obtain the metacresol product with lower purity (less than or equal to 90%).

Among the above-mentioned several methods for producing m-cresol products, the toluene sulfonation alkali fusion process is the earliest industrial process because of its mature technological route, but because this method consumes a large amount of acid and base, the amount of three wastes is large, the corrosion of equipment is serious, and in the course of the process, it also needs to treat solid material many times, so that the production is continuous and difficult, and its quality is poor. The isopropyl toluene method has the advantages of good product quality and suitability for large-scale production, but the one-time investment is too large, and the raw materials cannot be solved. The m-cresol produced by the o-xylene method and the phenol method has low purity, high production cost and serious three wastes. The raw materials of the tar crude distillation method are difficult to solve, the process route is complicated and the cost is high.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a process for preparing m-cresol.

The technical scheme adopted by the invention for solving the technical problems is as follows: the preparation process of m-cresol includes the following steps:

A. salt formation

Adding water, concentrated sulfuric acid and m-toluidine into a salt forming pot with a cooling jacket to react to generate m-toluidine sulfate aqueous solution;

B. diazotization

In a diazotization pot with a cooling device, adding m-toluidine sulfate aqueous solution of a salt forming pot at one time, adding sodium nitrite solution, reacting to generate m-toluidine diazonium salt, and then adding dilution water to react to complete the reaction.

C. Hydrolysis

Adding water, concentrated sulfuric acid, benzene and m-toluidine diazonium salt into an enamel hydrolysis pot with a heating jacket, refluxing for 1 hour, cooling to 40 ℃, and discharging.

D. Neutralization and water washing

And (3) standing and layering the hydrolysis feed liquid in a conical pot, removing the lower waste acid, neutralizing the residual sulfuric acid in the upper benzene layer by using a soda ash solution, washing with water, standing and layering, and removing the lower waste water.

The material obtained by the above reaction is separated, roughly distilled and rectified to obtain the finished product of m-cresol, the content of which can reach more than 99.5 percent, and the yield reaches 87 percent.

The invention has the advantages that: the main and auxiliary raw materials used in the production are sold at home, theprice is stable, and the quality completely meets the requirements of users; the process route has the advantages of small investment, low cost and high benefit, particularly the byproduct sulfuric acid can be recycled, no three-waste pollution is caused, various technical indexes of the product can reach and exceed the production indexes of the same industry in China and abroad, and various requirements can be completely met by users.

Detailed Description

The preparation process of m-cresol includes the following steps:

A. salt formation

In a salt forming pot with a cooling jacket, 3100L of water is added under stirring, 1000L of concentrated sulfuric acid is slowly added until the temperature of the feed liquid is not more than 60 ℃, and then the temperature is reduced to below 40 ℃, and 713Kg of m-toluidine is added to react to generate m-toluidine sulfate aqueous solution.

B. Diazotization

Adding m-toluidine sulfate aqueous solution in a salt forming pot in a diazotization pot with a cooling device, cooling to-5 ℃, slowly adding 1200L of sodium nitrite solution with the concentration of 40% to react to generate m-toluidine diazonium salt, stopping adding until the m-toluidine diazonium salt turns blue by testing with potassium iodide starch test paper, if the m-toluidine diazonium salt is excessive, removing the excessive sodium nitrite by using nitrogen sulfonic acid, and then adding dilution water to react to complete the reaction.

C. Hydrolysis

Adding 1800L of water, 480L of concentrated sulfuric acid and 3600L of benzene into an enamel hydrolysis pot with a heating jacket, heating to 70 ℃, slowly adding m-toluidine diazonium salt, refluxing for 1 hour after adding, cooling to 40 ℃, and discharging.

D. Neutralization and water washing

Claims

1. The preparation process of m-cresol is characterized by comprising the following process flows:

A. salt formation

Adding water and then slowly adding concentrated sulfuric acid in a salt forming pot with a cooling jacket under stirring, wherein the temperature of feed liquid is not more than 60 ℃, cooling to below 40 ℃ after the feed liquid is completely added, and adding m-toluidine to react to generate m-toluidine sulfate aqueous solution;

B. diazotization

Adding m-toluidine sulfate aqueous solution in a salt forming pot in a diazotization pot with a cooling device at one time, cooling to-5 ℃, slowly adding 40% sodium nitrite solution to react to generate m-toluidine diazo salt, stopping adding until the m-toluidine sulfate solution turns blue when tested by potassium iodide starch test paper, removing redundant sodium nitrite by using sulfamic acid if the m-toluidine sulfate solution is excessive, and then adding dilution water to react;

C. hydrolysis

Adding water, concentrated sulfuric acid and benzene into an enamel hydrolysis pot with a heating jacket, heating to 70 ℃, slowly adding m-toluidine diazonium salt, refluxing for 1 hour after adding, cooling to 40 ℃, and discharging;

D. neutralization and water washing

And standing and layering the hydrolysis feed liquid in a conical pot, removing the lower waste acid, neutralizing the residual sulfuric acid in the upper benzene layer by using a soda ash solution, washing with water, standing and layering, removing the lower waste water, separating the material obtained by the reaction, performing rough distillation and rectification to obtain the m-cresol finished product.