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Method for preparing o-vanillin

An ortho-vanillin and reaction technology, which is applied in the field of preparation of ortho-vanillin, can solve the problems of large amount of tar generated, difficult product separation and purification, etc., and achieves the advantages of reducing pollution, easily obtaining raw materials and simple process flow. Effect

Inactive Publication Date: 2012-08-22
SHENYANG INSTITUTE OF CHEMICAL TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

To sum up, at present, the by-product ortho-vanillin is produced when the guaiacol method and the Reimer-Tiemann reaction are used to synthesize vanillin. Among them, the yield of the Reimer-Tiemann reaction is relatively high, but the amount of tar generated in the reaction is large , the separation and purification of the product is very difficult. In addition, there are more guaiacol in the reaction that did not participate in the reaction, etc.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0022] Preparation steps of the present invention:

[0023] Step 1: reacting guaiacol with sulfonating agent and auxiliary agent at 50-120°C under normal pressure operating conditions to prepare 4-hydroxy-3-methoxybenzenesulfonic acid;

[0024] Step 2: While adjusting the pH value of the product in step 1 to alkaline, add glyoxylic acid and NaOH solution dropwise, control the dropwise addition within one hour, stir and react at a constant temperature of 40-100°C for 3-10 hours, Cool to room temperature after the reaction, and acidify with dilute sulfuric acid until the pH is about 2 to 6;

[0025] Step 3: Add 10% to 50% (mass fraction, the same below) of dilute sulfuric acid to the product in step 2 under stirring conditions, reflux at 70 to 150°C, react for 3 to 10 hours, filter and depressurize Rotary evaporation reaction solution obtains solid;

[0026] Step 4: Dissolve the solid obtained in Step 3 with deionized water, adjust the pH value to 10-12 with NaOH, and then ad...

Embodiment example 1

[0028] Into a 250ml three-neck flask, add 6.2g guaiacol, add 6.5g of 98% concentrated sulfuric acid dropwise, carry out stirring reaction in a constant temperature water bath at 85°C for 5 hours, then cool to room temperature, neutralize with 2mol / L NaOH, Filtrate; add 40ml of 2mol / L NaOH solution and 7.4g of 50% glyoxylic acid solution to the filtrate dropwise at 65°C, react under airtight conditions for 7 hours, adjust the solution to PH=5 with sulfuric acid, and then transfer to a place where there is condensation, Add 35ml of 30% sulfuric acid solution to a stirred three-necked flask, keep the temperature at 110°C, react for 4 hours and then spin evaporate to obtain a solid; adjust the spin evaporated solid to PH=11~12 with NaOH, add appropriate amount of deionized water to make solution, to obtain an electrolyte, placed in a stainless steel electrolytic cell. The anode is a graphite rod, the cathode is a stainless steel electrolytic cell, the temperature of the water bath...

Embodiment example 2

[0030] To a 250ml three-neck flask, add 6.2g of guaiacol, an appropriate amount of sodium sulfate solid and a part of 6.5g of 98% concentrated sulfuric acid at the same time, carry out stirring reaction in a constant temperature water bath at 85°C, and add the remaining concentrated sulfuric acid drop by drop at the same time, 5 After one hour, cool to room temperature, neutralize and filter with 2mol / L NaOH; add 40ml of 2mol / L NaOH solution and 7.4g of 50% glyoxylic acid solution to the filtrate dropwise at 65°C, and react for 7 hours under airtight conditions Finally, use sulfuric acid to adjust the solution to PH=5, then transfer it to a three-necked flask with condensation and stirring, add 35ml of 30% sulfuric acid solution, keep the temperature at 110°C, react for 4 hours and then spin evaporate to obtain a solid; the spin evaporated solid is washed with NaOH Adjust to PH = 11-12, add appropriate amount of deionized water to make a solution to obtain an electrolyte, and p...

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Abstract

The invention discloses a method for preparing o-vanillin and relates to a chemical synthesis method. The method comprises the following steps of: by utilizing the characteristics that a sulfonic acid group occupies a site and is removed by hydrolysis, firstly, sulfonating methyl catechol at the temperature of about 80 DEG C under the catalysis of concentrated sulfuric acid; then, performing a condensation reaction between the sulfonated methyl catechol and glyoxylic acid under the alkaling condition, and then, performing the hydrolysis at the temperature of about 110 DEG C to remove the sulfonic acid group; performing electrolytic oxidation, syneresis and filtration on a product, and then, extracting the product by using ethyl acetate when the product is hot; merging an upper extract layer; and drying, filtering and performing reduced pressure rotary distillation to obtain an o-vanillin product, and simultaneously recovering a low layer aqueous phase, and performing recrystallization to obtain a high-purity sodium sulfate crystal. The o-vanillin is derived from a byproduct generated by synthetizing vanillin at present, therefore, the yield is low, the demand is high, and the price is high. The technical problem that the o-vanillin is directly synthetized in China is solved by the method for preparing the o-vanillin, and meanwhile, lower layer extract liquor is recovered to obtain byproduct sodium sulfate with a high additional value. The method for preparing the o-vanillin is higher in economic benefit and social benefit.

Description

technical field [0001] The invention relates to a chemical synthesis method, in particular to a preparation method of ortho-vanillin. Background technique [0002] O-vanillin (o-vanillin) is an isomer of vanillin, scientific name 2-hydroxy-3-methoxybenzaldehyde, yellow-green needle-like crystal or crystalline powder, melting point 41~ 42°C, boiling point 260°C. Ortho-vanillin is easily soluble in organic solvents such as ethanol, ether, chloroform, glacial acetic acid, carbon disulfide, alkali solvent and pyridine. Ortho-vanillin has no fragrance and has a special smell. It can be used as an intermediate in organic synthesis, and can also be used in electroplating brighteners, medicines and cosmetics. In recent years, with the development of downstream product technology, it has become more and more widely used. [0003] At present, the process of synthesizing ortho-vanillin at home and abroad is basically blank, and the products mainly come from the by-products of vanill...

Claims

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Application Information

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IPC IPC(8): C25B3/02C07C47/58C07C45/65C25B3/23
Inventor 李云汪立忠陈杰盛林杰
Owner SHENYANG INSTITUTE OF CHEMICAL TECHNOLOGY
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