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Method for synthesizing para-tert-butylcatechol by using acid-mixed mixed system containing ionic liquid

A technology of tert-butyl catechol and ionic liquid, applied in the field of fine chemical synthesis, can solve problems such as low catalytic effect, environmental pollution, equipment corrosion, etc., and achieve the effects of less environmental pollution, easy recovery and less corrosiveness

Inactive Publication Date: 2012-08-22
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to solve the problems of environmental pollution, equipment corrosion and low acidity of a single ionic liquid, which are not as good as industrial alkylation catalysts such as sulfuric acid and hydrofluoric acid, caused by conventional acid catalysis in the current 4-TBC synthesis. A method for synthesizing p-tert-butylcatechol with mixed acid catalyst system containing ionic liquid
This process enhances the acidity of the ionic liquid, which not only solves the disadvantage of weak catalytic acidity of a single ionic liquid, but also solves the problem of corrosion of metal equipment, saves complicated post-treatment procedures such as neutralization and washing, reduces environmental pollution, and the catalyst is used Small amount, good stability, easy recycling, and reduced production costs

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Two ionic liquids were selected: 1-sulfonic acid butyl-3-methylimidazolium hydrogensulfate (IL1) and N-(4-sulfonic acid butyl)pyridine hydrogensulfate (IL2), the total amount of which was 0.002mol , the two ionic liquids were mixed according to the ratio of n(IL1):n(IL2) of 4:1. In aqueous solution, fix p-nitroaniline 0.025mg / ml (PK a =0.99) and mixed ionic liquid 0.08mmol / ml. Determination of 1-sulfonic acid butyl-3-methylimidazolium hydrogensulfate (IL1), N-(4-sulfonic acid butyl)pyridine hydrogensulfate (IL2) and mixed ionic liquid by Hammett indicator combined with ultraviolet spectroscopy The acid strengths are 1.41, 1.26, 1.17 respectively, the acid strength of the mixed acid is higher than that of the single ionic liquid, and the mixed acid system is used to catalyze the synthesis of 4-TBC.

[0020] Add 11g (0.1mol) catechol and 0.5062g IL1 and 0.1253g IL2 (the total amount of the two ionic liquids is 0.002mol, n(IL1):n(IL2)=4:1) into 100ml In a three-necked f...

Embodiment 2

[0023] The two ionic liquids 1-sulfonic acid butyl-3-methylimidazolium hydrogensulfate (IL1) and N-(4-sulfonic acid butyl)pyridine hydrogensulfate (IL2) separated by acetone in Example 1 As a mixed acid catalyst system, it is used to catalyze the synthesis of 4-TBC.

[0024] Two kinds of ionic liquids 1-sulfonic acid butyl-3-methylimidazolium bisulfate (IL1), N-(4-sulfonic acid Add a total of 0.6315g of butyl)pyridine bisulfate (IL2) into a 100ml three-necked flask equipped with a reflux condenser and a thermometer, stir and heat, and raise the temperature to 120°C (catechol has been melted), by constant pressure drop Add methyl tert-butyl ether (MTBE) dropwise into the funnel, and control the dropwise addition within 14~15min (dropping speed 15~20 drops / min), molar ratio n (catechol):n (MTBE):n (ILs) is 1:1:0.02; the reaction temperature is controlled at 120±5°C, and the reaction time is 90 minutes (methanol generated during the reaction can be distilled directly after being...

Embodiment 3

[0027] Mix the ionic liquid N-(4-sulfonic acid butyl)pyridine bisulfate (IL2) with sulfuric acid (the total amount of ionic liquid and sulfuric acid is 0.002mol), wherein the mass fraction of sulfuric acid is 25% of the mixed acid, in aqueous solution In, fixed o-nitroaniline 0.025mg / ml (PK a =-0.2) and mixed acid 0.08mmol / ml. The acid strength of the mixed acid catalyst was -0.141 measured by Hammett indicator combined with ultraviolet spectroscopy, which was higher than that of a single ionic liquid. The mixed acid system was used to catalyze the synthesis of 4-TBC.

[0028] 11g (0.1mol) catechol and 0.3032g IL2 were mixed with 0.1013g H 2 SO 4 (the total amount of ionic liquid and sulfuric acid is 0.002mol, H 2 SO 4 The mass content is 25% of the mixed acid) into a 100ml three-necked flask equipped with a reflux condenser and a thermometer, stirred and heated, and the temperature was raised to 120°C (catechol has been melted), and the methanol was added dropwise from a ...

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Abstract

The invention provides a method for synthesizing para-tert-butylcatechol by using an acid-mixed mixed system containing ionic liquid, which comprises the following steps: stirring, heating and melting catechol and an acid-mixed catalyst, adding an alkylating agent in a droplet mode within 30 min, performing condensation backflow reaction for 60-150 min under the temperature of 110-150 DEG C, extracting reaction liquid to separate the ionic liquid for recycling, performing extract-phase reduced pressure distillation and purification and finally obtaining the para-tert-butylcatechol, wherein the mole ratio of the catechol to the alkylating agent to the acid-mixed catalyst is 1:0.5-2.0:0.01-0.1. The acid-mixed catalyst is formed by mixing two types of acidic ionic liquid or mixing acidic ionic liquid and bronsted acid. The method for synthesizing the para-tert-butylcatechol by using the acid-mixed mixed system containing the ionic liquid overcomes the defect that simple ionic liquid is weak in acidity and poor in catalysis effect, facilitates catalytic alkylation reaction and is small in corrosivity and environmental pollution, the conversion rate of the catechol reaches up to 87.2%, and the selectivity of 4-para-tert-butylcatechol (4-TBC) reaches up to 77.3%.

Description

technical field [0001] The invention belongs to the technical field of synthesis of fine chemicals, in particular to a method for synthesizing p-tert-butylcatechol with a mixed acid catalyst system containing ionic liquid. Background technique [0002] 4-tert-butylcatechol (4-TBC for short) is a white or light yellow crystal, soluble in acetone, methanol, ethanol and other organic solvents, insoluble in water. As an important fine chemical product, it is mainly used as a high-efficiency polymerization inhibitor. The American ASTM Association designated it as a general-purpose polymerization inhibitor such as styrene, and can be used as an antioxidant for polypropylene, synthetic rubber, lubricating oil, caprolactam, etc. Agents are widely used in the chemical industry. At present, the main synthesis method of 4-TBC is the alkylation reaction of catechol. In the research work of synthesizing 4-TBC, the development of alkylation catalyst has received more and more attention. ...

Claims

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Application Information

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IPC IPC(8): C07C39/08C07C37/16C07C37/14B01J31/02
Inventor 张文林李春利杜威孙如意孟楠方静王晓文王洪海
Owner HEBEI UNIV OF TECH
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