Clean production method of vanillin

Abstract

The invention discloses a clean production method of oxidizing 3-methoxy-4-hydroxy mandelic acid for joint production of vanillin and superfine silver powder under an alkaline condition by adopting silver nitrate. The clean production method comprises the following steps: adding a silver nitrate solution, a 3-methoxy-4-hydroxy mandelic acid solution and a sodium hydroxide solution in a parallel flow manner into a reactor, reacting to generate a 3-methoxy-4-hydroxy acetophenone sodium solution and superfine silver powder, filtering and separating the generated silver powder, washing with deionized water and ethyl alcohol sequentially, and drying to obtain the superfine silver powder, wherein the reduction yield of the silver powder is 99.4 per cent to 100 per cent; acidizing filter liquor after the silver powder is separated, performing decarboxylation on 3-methoxy-4-hydroxy benzoylformic acid to generate the vanillin, using methylbenzene to extract the vanillin therein, recycling the methylbenzene solvent, and performing recrystallization on residues in an ethanol aqueous solution to obtain the vanillin, wherein the oxidation yield of the methoxy-4-hydroxy mandelic acid is 95.7 per cent to 98.5 per cent. The silver nitrate is taken as an oxidizing agent to prepare the vanillin, so that the oxidation yield is improved, and the oxidation reaction time is shortened. Two practical fine chemical products can be produced simultaneously, the raw materials can be sufficiently utilized, the generation of waste materials is reduced, the production cost is reduced, and the technological process is safe and environment-friendly.

Description

technical field

[0001] The invention relates to a clean production method of vanillin, in particular to a clean production method for jointly producing vanillin and superfine silver powder by oxidizing 3-methoxy-4-hydroxymandelic acid under alkaline conditions with silver nitrate, Two kinds of practical fine chemical products can be obtained at the same time, belonging to the fields of new chemical materials and environmental protection. Background technique

[0002] Vanillin (English name Vanillin), chemical name 3-methoxy-4-hydroxybenzaldehyde, chemical formula C 8 h 8 O 3 , Molecular weight 152.2, white needle crystal, melting point 81-83 ℃, boiling point 284 ℃, slightly soluble in water, soluble in ethanol and chloroform, with vanilla aroma and strong milky aroma. Vanillin is one of the most produced synthetic flavors in the world, and it is also an important intermediate for synthetic drugs and chemical products. China has a production capacity of 25,000 tons of vani...

Examples

Embodiment 1

[0035] A 1000mL four-neck reaction flask equipped with a stirrer, a condenser and a constant pressure dropping funnel was installed on a constant temperature water bath, and 59.5g of guaiacol (0.48 mol) and 100mL of 4.8mol / L sodium hydroxide were added thereto (0.48 mol), generate sodium guaiacol solution, add 74.1g40% glyoxylic acid (0.4mol) and sodium hydroxide (0.48 mol) of 100mL4.8mol / L respectively through two constant pressure dropping funnels, control The temperature is 20-40°C and the pH is 11-13, and the feed is fed for 1-2 hours. After the feed is completed, the reaction is continued for 4-6 hours to complete the condensation reaction. Use about 200mL of sulfuric acid with a mass percentage concentration of 10% to neutralize the condensation reaction solution to pH 5-6, and use 100mL toluene to separate the unconverted guaiacol in two extractions to obtain the vanillin synthesis intermediate 3-methanol Oxygen-4-hydroxymandelic acid condensation reaction solution,...

Embodiment 2

[0040] Obtain the vanillin synthesis intermediate 3-methoxyl-4-hydroxymandelic acid condensation reaction solution in the same manner as in the examples, and determine the content of MHMA in it to be 0.66mol / L (0.32mol).

[0041] Add silver nitrate solution 237 mL3 mol / L (0.71mol), sodium hydroxide solution 150 mL4.8 mol / L (0.66mol) and the above 3-methoxy-4-hydroxy Mandelic acid solution, react to generate 3-methoxyl-4-hydroxyacetophenone sodium solution and ultra-fine silver powder, the feeding speed is controlled to keep the precipitate generated in the reaction solution as off-white, and the temperature of the reaction solution is maintained at 20-40°C and React at pH 11-13 for 0.5-1 hour, raise the temperature to 50-60°C after feeding is completed, continue to stir and react for 0.5-1 hour to make MHMA completely react, then add 12.0g 20% ​​formic acid solution (0.05mol) to make excess silver nitrate reduction.

[0042] The resulting silver powder was separated by fil...

technical field

[0001] The invention relates to a clean production method of vanillin, in particular to a clean production method for jointly producing vanillin and superfine silver powder by oxidizing 3-methoxy-4-hydroxymandelic acid under alkaline conditions with silver nitrate, Two kinds of practical fine chemical products can be obtained at the same time, belonging to the fields of new chemical materials and environmental protection. Background technique

[0002] Vanillin (English name Vanillin), chemical name 3-methoxy-4-hydroxybenzaldehyde, chemical formula C 8 h 8 O 3 , Molecular weight 152.2, white needle crystal, melting point 81-83 ℃, boiling point 284 ℃, slightly soluble in water, soluble in ethanol and chloroform, with vanilla aroma and strong milky aroma. Vanillin is one of the most produced synthetic flavors in the world, and it is also an important intermediate for synthetic drugs and chemical products. China has a production capacity of 25,000 tons of vani...

Examples

Embodiment 1

[0035] A 1000mL four-neck reaction flask equipped with a stirrer, a condenser and a constant pressure dropping funnel was installed on a constant temperature water bath, and 59.5g of guaiacol (0.48 mol) and 100mL of 4.8mol / L sodium hydroxide were added thereto (0.48 mol), generate sodium guaiacol solution, add 74.1g40% glyoxylic acid (0.4mol) and sodium hydroxide (0.48 mol) of 100mL4.8mol / L respectively through two constant pressure dropping funnels, control The temperature is 20-40°C and the pH is 11-13, and the feed is fed for 1-2 hours. After the feed is completed, the reaction is continued for 4-6 hours to complete the condensation reaction. Use about 200mL of sulfuric acid with a mass percentage concentration of 10% to neutralize the condensation reaction solution to pH 5-6, and use 100mL toluene to separate the unconverted guaiacol in two extractions to obtain the vanillin synthesis intermediate 3-methanol Oxygen-4-hydroxymandelic acid condensation reaction solution,...

Embodiment 2

[0040] Obtain the vanillin synthesis intermediate 3-methoxyl-4-hydroxymandelic acid condensation reaction solution in the same manner as in the examples, and determine the content of MHMA in it to be 0.66mol / L (0.32mol).

[0041] Add silver nitrate solution 237 mL3 mol / L (0.71mol), sodium hydroxide solution 150 mL4.8 mol / L (0.66mol) and the above 3-methoxy-4-hydroxy Mandelic acid solution, react to generate 3-methoxyl-4-hydroxyacetophenone sodium solution and ultra-fine silver powder, the feeding speed is controlled to keep the precipitate generated in the reaction solution as off-white, and the temperature of the reaction solution is maintained at 20-40°C and React at pH 11-13 for 0.5-1 hour, raise the temperature to 50-60°C after feeding is completed, continue to stir and react for 0.5-1 hour to make MHMA completely react, then add 12.0g 20% ​​formic acid solution (0.05mol) to make excess silver nitrate reduction.

[0042] The resulting silver powder was separated by fil...