Synthetic process of 2,3-dichlorobenzaldehyde

Abstract

The invention discloses a synthetic process of 2,3-dichlorobenzaldehyde. The synthetic process comprises the steps that 2,3-dichlorotoluene is used as a raw material, bromine is used as an auxiliary material, azodiisobutyronitrile is used as a catalyst, the bromine utilization rate is improved through hydrogen peroxide, the generated 2,3-dichlorobenzyl bromide is hydrolyzed into 2,3-dichlorobenzaldehyde in 30 wt% of sodium carbonate water solution, the 2,3-dichlorobenzaldehyde is generated by using hydrogen bromide to catalyze hydrogen peroxide oxidization, the total yield is 70% or above, and the product purity is 99.25% or above. The raw material conversion rate and selectivity of the process are high. In addition, the by-product production rate is reduced, the bromine utilization rate is improved, the bromine usage amount is decreased, and the synthetic process is greener and environmentally friendly compared with a traditional metal-catalyzed oxidation technology.

Description

technical field

[0001] The invention relates to the technical field of organic synthesis, in particular to a synthesis process of 2,3-dichlorobenzaldehyde. Background technique

[0002] 2,3-Dichlorobenzaldehyde, as an intermediate in the synthesis of new antihypertensive drug felodipine and an intermediate in dyes, is an important aromatic aldehyde and has a wide range of uses in medicine and dyes. As a fine chemical product with extensive market demand, the research on its highly selective synthesis process has important environmental and economic benefits.

[0003] At present, many units in China are able to produce 2,3-dichlorobenzaldehyde. Most of the synthesis processes use 2,3-dichloroaniline hydrochloride or 2,3-dichlorotoluene as raw materials, of which 2, 3-Dichlorotoluene is widely used.

[0004] The main process routes are: (1) 2,3-dichloroaniline hydrochloride is used as raw material to synthesize diazonium salt, and then hydrolyzed with formaldehyde oxime to p...

Examples

Embodiment 1

[0026] In a 1L reactor, add 61.5g of 2,3-dichlorotoluene, 3.075g of azobisisobutyronitrile (5%), and 215.25g of 1,2-dichloroethane, stir and heat at 75°C and start adding 44g of it dropwise Bromine, reflux reaction until the bromine red fades, intermittently add 136.2g of 27.5% hydrogen peroxide dropwise to continue the reaction until the bromine red is no longer generated. Add 49.2g of 30% sodium carbonate aqueous solution to the reaction solution, reflux for 8 hours, and recover 1,2-dichloroethane at the same time.

[0027] The hydrolyzate was filtered at 80°C, 246g of 1,4-dioxane was added to the organic phase, 6.15g of 40% catalyst HBr was added, 38.3g of 27.5% hydrogen peroxide was added, and the reaction was carried out at 25°C for 7h. The reaction system was extracted three times with 1,2-dichloroethane, and the organic phases were combined and concentrated to obtain crude 2,3-dichlorobenzaldehyde, which was recrystallized from ethanol to obtain 48.19 g of 2,3-dichlorob...

Embodiment 2

[0029] In a 1L reactor, add 61.5g of 2,3-dichlorotoluene, 1.845g of azobisisobutyronitrile (3%), and 184.5g of 1,2-dichloroethane, stir and heat at 78°C and start dropping 42.37 g bromine, reflux reaction until the bromine red color fades, intermittently add 136.8g 27.5% hydrogen peroxide dropwise to continue the reaction until the bromine red color is no longer generated. Add 52.275g of 30% sodium carbonate aqueous solution to the reaction solution, reflux for 10h, and recover 1,2-dichloroethane at the same time.

[0030] The hydrolyzate was filtered at 80°C, 369g of 1,4-dioxane was added to the organic phase, 15.375g of 40% catalyst HBr was added, 39.156g of 27.5% hydrogen peroxide was added, and the reaction was carried out at 35°C for 7h. The reaction system was extracted three times with 1,2-dichloroethane, and the combined organic phases were concentrated to obtain crude 2,3-dichlorobenzaldehyde, which was recrystallized from ethanol to obtain 46.79 g of 2,3-dichlorobenz...

Embodiment 3

[0032] In a 1L reactor, add 61.5g of 2,3-dichlorotoluene, 2.46g of azobisisobutyronitrile (4%), and 210.7g of 1,2-dichloroethane, stir and heat at 80°C and start adding 41.6 g bromine, reflux reaction until the red color of bromine fades, and intermittently add 137g of 27.5% hydrogen peroxide dropwise to continue the reaction until the red color of bromine is no longer generated. Add 55.35g of 30% sodium carbonate aqueous solution to the reaction solution, reflux for 12 hours, and recover 1,2-dichloroethane at the same time.

[0033] The hydrolyzate was filtered at 80°C, 338.25g of 1,4-dioxane was added to the organic phase, 10.25g of 48% catalyst HBr was added, 40.2g of 27.5% hydrogen peroxide was added, and the reaction was carried out at 30°C for 7h. The reaction system was extracted three times with 1,2-dichloroethane, and the organic phases were combined and concentrated to obtain crude 2,3-dichlorobenzaldehyde, which was recrystallized from ethanol to obtain 47.66g of 2,...

technical field

[0001] The invention relates to the technical field of organic synthesis, in particular to a synthesis process of 2,3-dichlorobenzaldehyde. Background technique

[0002] 2,3-Dichlorobenzaldehyde, as an intermediate in the synthesis of new antihypertensive drug felodipine and an intermediate in dyes, is an important aromatic aldehyde and has a wide range of uses in medicine and dyes. As a fine chemical product with extensive market demand, the research on its highly selective synthesis process has important environmental and economic benefits.

[0003] At present, many units in China are able to produce 2,3-dichlorobenzaldehyde. Most of the synthesis processes use 2,3-dichloroaniline hydrochloride or 2,3-dichlorotoluene as raw materials, of which 2, 3-Dichlorotoluene is widely used.

[0004] The main process routes are: (1) 2,3-dichloroaniline hydrochloride is used as raw material to synthesize diazonium salt, and then hydrolyzed with formaldehyde oxime to p...

Examples

Embodiment 1

[0026] In a 1L reactor, add 61.5g of 2,3-dichlorotoluene, 3.075g of azobisisobutyronitrile (5%), and 215.25g of 1,2-dichloroethane, stir and heat at 75°C and start adding 44g of it dropwise Bromine, reflux reaction until the bromine red fades, intermittently add 136.2g of 27.5% hydrogen peroxide dropwise to continue the reaction until the bromine red is no longer generated. Add 49.2g of 30% sodium carbonate aqueous solution to the reaction solution, reflux for 8 hours, and recover 1,2-dichloroethane at the same time.

[0027] The hydrolyzate was filtered at 80°C, 246g of 1,4-dioxane was added to the organic phase, 6.15g of 40% catalyst HBr was added, 38.3g of 27.5% hydrogen peroxide was added, and the reaction was carried out at 25°C for 7h. The reaction system was extracted three times with 1,2-dichloroethane, and the organic phases were combined and concentrated to obtain crude 2,3-dichlorobenzaldehyde, which was recrystallized from ethanol to obtain 48.19 g of 2,3-dichlorob...

Embodiment 2

[0029] In a 1L reactor, add 61.5g of 2,3-dichlorotoluene, 1.845g of azobisisobutyronitrile (3%), and 184.5g of 1,2-dichloroethane, stir and heat at 78°C and start dropping 42.37 g bromine, reflux reaction until the bromine red color fades, intermittently add 136.8g 27.5% hydrogen peroxide dropwise to continue the reaction until the bromine red color is no longer generated. Add 52.275g of 30% sodium carbonate aqueous solution to the reaction solution, reflux for 10h, and recover 1,2-dichloroethane at the same time.

[0030] The hydrolyzate was filtered at 80°C, 369g of 1,4-dioxane was added to the organic phase, 15.375g of 40% catalyst HBr was added, 39.156g of 27.5% hydrogen peroxide was added, and the reaction was carried out at 35°C for 7h. The reaction system was extracted three times with 1,2-dichloroethane, and the combined organic phases were concentrated to obtain crude 2,3-dichlorobenzaldehyde, which was recrystallized from ethanol to obtain 46.79 g of 2,3-dichlorobenz...

Embodiment 3

[0032] In a 1L reactor, add 61.5g of 2,3-dichlorotoluene, 2.46g of azobisisobutyronitrile (4%), and 210.7g of 1,2-dichloroethane, stir and heat at 80°C and start adding 41.6 g bromine, reflux reaction until the red color of bromine fades, and intermittently add 137g of 27.5% hydrogen peroxide dropwise to continue the reaction until the red color of bromine is no longer generated. Add 55.35g of 30% sodium carbonate aqueous solution to the reaction solution, reflux for 12 hours, and recover 1,2-dichloroethane at the same time.

[0033] The hydrolyzate was filtered at 80°C, 338.25g of 1,4-dioxane was added to the organic phase, 10.25g of 48% catalyst HBr was added, 40.2g of 27.5% hydrogen peroxide was added, and the reaction was carried out at 30°C for 7h. The reaction system was extracted three times with 1,2-dichloroethane, and the organic phases were combined and concentrated to obtain crude 2,3-dichlorobenzaldehyde, which was recrystallized from ethanol to obtain 47.66g of 2,...