CN108299170B - Preparation method of 2,4, 6-trimethylbenzaldehyde - Google Patents
Preparation method of 2,4, 6-trimethylbenzaldehyde Download PDFInfo
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- CN108299170B CN108299170B CN201711500116.1A CN201711500116A CN108299170B CN 108299170 B CN108299170 B CN 108299170B CN 201711500116 A CN201711500116 A CN 201711500116A CN 108299170 B CN108299170 B CN 108299170B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/45—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by condensation
- C07C45/455—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by condensation with carboxylic acids or their derivatives
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Abstract
The inventionDiscloses a preparation method of 2,4, 6-trimethylbenzaldehyde which is an intermediate of herbicide tralkoxydim, belonging to the technical field of agricultural chemical raw materials. The method comprises the following steps: adding N, N-dimethylformamide and anhydrous organic solvent into a reaction bottle, and slowly dropwise adding a certain amount of POCl3Stirring at-10 ℃ for 20min, then dropwise adding 2,4, 6-trimethylbenzene, controlling the temperature below-5 ℃ and stirring for 10min, carrying out reflux reaction for 4.0 h-8.0 h, after the reaction is finished, removing the organic solvent under reduced pressure, slowly pouring into a certain amount of ice water, neutralizing the mixed solution with saturated sodium carbonate until the pH value is 7, extracting with ethyl acetate for a plurality of times, combining organic layers, drying and desolventizing to obtain the 2,4, 6-trimethylbenzaldehyde (I).
Description
Technical Field
The invention relates to a preparation method of 2,4, 6-trimethylbenzaldehyde which is an intermediate of trimethylbenzone and is a cyclohexanedione herbicide, in particular to a method for preparing 2,4, 6-trimethylbenzaldehyde in one step by taking 2,4, 6-trimethylbenzene as a raw material under the conditions of an organic solvent and a catalyst, and belongs to the technical field of agricultural chemical raw materials.
Background
The 2,4, 6-trimethyl benzaldehyde is commonly called rice aldehyde, is colorless or light yellow liquid, has a melting point of 14 ℃, and is stable at normal temperature. As an important intermediate, the derivative is widely applied to pesticides, medicines and resin additives and is one of fine chemicals with high added value. Due to steric hindrance of three methyl groups in the molecular structure, the preparation method has been concerned.
For example the gatterman-koch process: queen et al report that 2,4, 6-trimethylbenzene reacts with CO and HCl gases, and the yield of 2,4, 6-trimethylbenzaldehyde is 80-90% by using an aluminum trichloride catalyst. The method has high yield, but high pressure requirement and large equipment investment, and the used CO has certain toxicity and does not meet the technical requirement of green chemistry.
Acetone cyanohydrin acylation method: RAHM A and the like take 2,4, 6-trimethylbenzene and acetone cyanohydrin as raw materials, and react in dichloroethane by taking aluminum trichloride as a catalyst, and the method has simple and convenient post-treatment, but has lower yield of 48 percent, large catalyst dosage and long reaction time.
Ruff reaction acylation method: fuson R.C. uses 2,4, 6-trimethylbenzene as raw material, zinc cyanide as acylating agent and aluminium chloride as catalyst, and its yield is 75-81%. The route has the defects of using extremely toxic zinc cyanide and generating a large amount of HCl gas, using a large amount of catalyst and increasing the post-treatment difficulty.
CN102924252A reports a dichloromethyl methyl ether acylation method, which takes dichloromethyl ether and 2,4, 6-trimethylbenzene as raw materials to synthesize 2,4, 6-trimethylbenzaldehyde in one step under the catalysis of aluminum trichloride. The method has the advantages of 81-89 percent of yield and higher yield, and has the defects that the dosage of the used aluminum trichloride is 2-3 times of that of 2,4, 6-trimethylbenzene, the acylating reagent dichloromethyl ether is not easy to obtain, a large amount of phosphorus pentachloride and phosphorus oxychloride catalysts are needed for preparation, and the cost is increased.
Johns et al use N, N-dimethylformamide as the formylation reagent to react with 2,4, 6-trimethylbenzene to prepare the intermediate, but uses triflic anhydride catalyst, the price is higher, and other reagents and yield used in the reaction are not reported.
Fergus et al adopts formylation reagent N, N-dimethyl formamide, under the condition of no catalyst, after dropping reagent at-78 deg.C, the reaction is overnight at room temperature, the yield of reaction is not reported, said method requires very low temperature, has high requirements for equipment, and its reaction time is very long, and its cost is raised.
Based on the defects in the prior art, the development of a novel preparation method for preparing the 2,4, 6-trimethylbenzaldehyde under mild conditions and with high yield has very high application value.
Disclosure of Invention
The invention aims to provide a preparation method of a tralkoxydim intermediate 2,4, 6-trimethylbenzaldehyde, which has the advantages of low cost, simple and convenient post-treatment and high yield.
The invention provides a preparation method of 2,4, 6-trimethylbenzaldehyde, which comprises the following reaction route:
the preparation method of the 2,4, 6-trimethylbenzaldehyde comprises the following steps:
mixing N, N-dimethylformamide and anhydrous organic solvent, adding a certain amount of catalyst POCl3Stirring at-10 deg.C for 20min, adding 2,4, 6-trimethylbenzene dropwise, stirring at-5 deg.C for 10min, and refluxing to react completely; after the post-treatment, 2,4, 6-trimethyl benzaldehyde is obtained.
The feeding molar ratio of the raw materials of 2,4, 6-trimethylbenzene and N, N-dimethylformamide is 1: 4-8.
In some embodiments, the anhydrous organic solvent is preferably dichloromethane or chloroform, most preferably dichloromethane.
In some embodiments, the starting materials 2,4, 6-trimethylbenzene are reacted with POCl3The feeding molar ratio of (A) to (B) is 1: 1-3, preferably 1: 2.
Preferably, the preparation method of the present application comprises the following post-treatments: after the reaction is finished, the organic solvent is removed under reduced pressure, the mixture is slowly poured into a certain amount of ice water, the mixed solution is neutralized by saturated sodium carbonate until the pH value is 7, ethyl acetate is extracted for several times, organic layers are combined, dried and desolventized to obtain the 2,4, 6-trimethyl benzaldehyde.
In some embodiments, the reflux reaction time is 4.0h to 8.0 h; POCl3The addition mode of (2) is slow dripping.
Compared with the prior art, the invention has the following advantages:
1) the invention improves the solvent, and the applicant finds that the selection of the solvent has great influence on the yield of the reaction in a reaction system which takes N, N-dimethylformamide as an acylation reagent and phosphorus oxychloride as a catalyst through a large number of experiments. When dichloromethane or trichloromethane is used as a reaction solvent, the reaction yield is high; especially when dichloromethane is used as a reaction solvent, the yield is highest, and the product content is also improved.
2) The method takes N, N-dimethylformamide as an acylation reagent, and has the advantages of simple and easily obtained raw materials and low cost; phosphorus oxychloride is used as a catalyst, so that the catalyst is low in cost;
3) the reaction condition is mild, the requirement on equipment is low, the cost is reduced, the yield is high, the post-treatment is easy to operate, and the popularization and the application are convenient; the used organic solvent (dichloromethane or trichloromethane) has low boiling point, can be easily removed, can be recycled, and is green and environment-friendly.
Detailed Description
The following examples are intended to illustrate the invention without further limiting it.
The reaction equation of the invention is as follows:
example 1
43.8g (0.6mol) of N, N-dimethylformamide and 150mL of anhydrous dichloromethane were added to a reaction flask, and 30.6g (0.2mol) of POCl was slowly added dropwise3Stirring at-10 deg.C for 20min, adding 12.0g (0.1mol) of 2,4, 6-trimethylbenzene dropwise, stirring at-5 deg.C for 10min, and reflux reacting for 6.0 h. And (3) post-treatment process: dichloromethane was removed under reduced pressure, the mixture was slowly poured into 450mL of ice water, the mixture was neutralized with saturated sodium carbonate to pH 7, and then extracted three times with 100mL of ethyl acetate, and the organic layers were combined, dried, and desolventized to obtain liquid 2,4, 6-trimethylbenzaldehyde 13.4g, content 95.0%, yield 90.3%.
Example 2
43.8g (0.6mol) of N, N-dimethylformamide and 150mL of anhydrous chloroform were added to a reaction flask, and 30.6g (0.2mol) of POCl was slowly added dropwise3Stirring at-10 deg.CAfter 20min, 12.0g (0.1mol) of 2,4, 6-trimethylbenzene is dripped, the temperature is controlled below minus 5 ℃, the mixture is stirred for 10min, and the reflux reaction is carried out for 6.0 h. And (3) post-treatment process: chloroform was removed under reduced pressure, the mixture was slowly poured into 450mL of ice water, the mixture was neutralized with saturated sodium carbonate until the pH became 7, and then extracted three times with 100mL of ethyl acetate, and the organic layers were combined, dried, and desolventized to obtain 11.3g of liquid 2,4, 6-trimethylbenzaldehyde, the content of which was 90.0%, and the yield was 76.2%.
It will be understood by those skilled in the art that any changes, equivalents and improvements made within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (4)
1. A preparation method of 2,4, 6-trimethylbenzaldehyde comprises the following steps:
mixing N, N-dimethylformamide and anhydrous organic solvent, adding a certain amount of catalyst POCl3Stirring at-10 deg.C for 20min, adding 2,4, 6-trimethylbenzene dropwise, stirring at-5 deg.C for 10min, and refluxing to react completely; after post-treatment, 2,4, 6-trimethyl benzaldehyde is obtained; the feeding mol ratio of the raw material 2,4, 6-trimethylbenzene to the N, N-dimethylformamide is 1: 4-8; the anhydrous organic solvent is dichloromethane; raw materials of 2,4, 6-trimethylbenzene and POCl3The feeding mol ratio of (A) to (B) is 1: 1-3.
2. The process for preparing 2,4, 6-trimethylbenzaldehyde according to claim 1, wherein the starting materials are 2,4, 6-trimethylbenzene and POCl3The feeding molar ratio of (A) to (B) is 1: 2.
3. The method for producing 2,4, 6-trimethylbenzaldehyde according to claim 1, wherein the post-treatment method comprises: after the reaction, the organic solvent is removed under reduced pressure, the mixture is slowly poured into a certain amount of ice water, the mixed solution is neutralized by saturated sodium carbonate until the pH value is 7, ethyl acetate is extracted for a plurality of times, organic layers are combined, dried and desolventized to obtain the 2,4, 6-trimethyl benzaldehyde.
4. Root of herbaceous plantsThe process for the preparation of 2,4, 6-trimethylbenzaldehyde according to claim 1, characterized in that: the reflux reaction time is 4.0 h-8.0 h; POCl3The addition mode of (2) is slow dripping.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2485237A (en) * | 1946-08-24 | 1949-10-18 | Du Pont | Synthesis of aromatic aldehydes |
| CN102924252A (en) * | 2012-11-20 | 2013-02-13 | 徐州宇家化工科技有限公司 | Preparation method of 2,4,6-trimethyl benzaldehyde |
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| GB0424051D0 (en) * | 2004-10-29 | 2004-12-01 | Nipri Ltd | Compounds and compositions |
| CN102775290B (en) * | 2012-07-23 | 2015-08-26 | 昆明理工大学 | 2-chloromethyl-5,6-dimethoxy-3-methyl isophthalic acid, the preparation method of 4-para benzoquinone |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2485237A (en) * | 1946-08-24 | 1949-10-18 | Du Pont | Synthesis of aromatic aldehydes |
| CN102924252A (en) * | 2012-11-20 | 2013-02-13 | 徐州宇家化工科技有限公司 | Preparation method of 2,4,6-trimethyl benzaldehyde |
Non-Patent Citations (1)
| Title |
|---|
| 4-苄氧基-2-甲氧基苯甲醛的合成;卢永仲等;《鲁东大学学报(自然科学版)》;20110715;第27卷(第3期);第254页第1.2.2节 * |
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