CN110256217B - Preparation method of o-methoxybenzaldehyde - Google Patents
Preparation method of o-methoxybenzaldehyde Download PDFInfo
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- CN110256217B CN110256217B CN201910353878.6A CN201910353878A CN110256217B CN 110256217 B CN110256217 B CN 110256217B CN 201910353878 A CN201910353878 A CN 201910353878A CN 110256217 B CN110256217 B CN 110256217B
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Abstract
The invention provides a preparation method of o-methoxybenzaldehyde, which comprises the following steps of 1) mixing benzaldehyde derivatives, anhydrous methanol, palladium acetate, an oxidant and an aniline ligand in a solvent, and then carrying out methoxylation reaction at a certain temperature to obtain a reaction liquid A; 2) filtering the reaction liquid A, and extracting a filtrate B obtained by filtering with an extracting agent to obtain a lower layer extract C; 3) drying the extract C by using a drying agent, removing water, filtering, adding silica gel powder into the filtrate D obtained by filtering, and spin-drying the dichloromethane to obtain a mixture E; 4) and separating and purifying the mixture E by chromatography to obtain o-methoxybenzaldehyde. The o-methoxybenzaldehyde prepared by the method has high yield and purity, the yield can reach 67%, and the method has the advantages of simple preparation process, easy operation, short reaction time and great improvement on production efficiency.
Description
Technical Field
The invention relates to the technical field of organic synthesis, and particularly relates to a preparation method of o-methoxybenzaldehyde.
Background
O-methoxybenzaldehyde is a common organic synthetic intermediate widely found in drugs, natural products, such as the adrenomimetic drug, tussilago. It can also be used as intermediate of perfume, medicine and fluorescent whitening agent, such as producing fluorescent whitening agent CBS, triphenylmethane dye and mothproofing agent N.
Due to weak coordination of aldehyde group, sensitivity to oxidant and weak guiding effect, the o-position reaction of benzaldehyde is difficult, and then hydroxyl H in methanol is not easy to leave, so that methoxyl group is difficult to position at o-position of aldehyde group in the reaction.
Therefore, the development of the preparation method of the o-methoxybenzaldehyde, which has the advantages of simple preparation process, short reaction time, mild reaction conditions, simple post-treatment, high yield and strong substrate expansibility, has very important significance.
Disclosure of Invention
In view of the above, the invention aims to provide a method for preparing o-methoxybenzaldehyde, so as to solve the problems of complex synthesis method, long reaction time, harsh reaction conditions, low product yield and purity and high environmental protection pressure of the existing o-methoxybenzaldehyde.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a preparation method of o-methoxybenzaldehyde comprises the following steps:
1) mixing benzaldehyde derivatives, absolute methanol, palladium acetate, an oxidant and an aniline ligand in a solvent, and then carrying out methoxylation reaction at a certain temperature to obtain a reaction liquid A;
2) filtering the reaction liquid A, and extracting a filtrate B obtained by filtering with an extracting agent to obtain a lower layer extract C;
3) drying the extract C by using a drying agent, removing water, filtering, adding silica gel powder into the filtrate D obtained by filtering, and spin-drying the dichloromethane to obtain a mixture E;
4) and separating and purifying the mixture E by chromatography to obtain o-methoxybenzaldehyde.
Optionally, the molar ratio of the benzaldehyde derivative, the anhydrous methanol, the palladium acetate, the oxidant and the aniline ligand in the step 1) is 1: 15-20: 0.1: 2: 0.4.
Optionally, the reaction temperature of the methoxylation reaction in the step 1) is 40-80 ℃, and the reaction time is 18-32 h.
Optionally, the substituent on the benzaldehyde of the benzaldehyde derivative in step 1) is one of methyl, methoxy, phenyl, fluorine, chlorine and bromine, the aniline ligand is one of m-trifluoromethylaniline and o-trifluoromethylaniline, the oxidant is one of potassium persulfate and sodium persulfate, and the solvent is one of dichloromethane, 1, 2-dichloroethane and toluene.
Optionally, the ratio of the dosage of the benzaldehyde derivative in the step 1) to the dosage of the solvent is 1 mol: 10-15L.
Optionally, the extractant in the step 2) is a mixed solution of saturated sodium bicarbonate aqueous solution and dichloromethane; the volume ratio of the saturated sodium bicarbonate aqueous solution to the dichloromethane is 1: 2-3.
Optionally, the drying agent in the step 3) is anhydrous sodium sulfate, and the ratio of the using amount of the extract C to the using amount of the drying agent is 1L: 25 g.
Optionally, the chromatography in step 4) comprises column chromatography.
Optionally, the column chromatography comprises the steps of:
mixing silica gel powder with petroleum ether to obtain paste, and pouring into chromatographic column;
adding petroleum ether to the column and pressurizing until the flow rate is constant, so that the volume of the column bed is compressed to 9/10 which is equal to the original volume of the column bed;
and (3) placing the mixture E in a chromatographic column by adopting a dry method for sample loading, developing and eluting, after the elution is finished, point-collecting eluent of a target product, and then, spin-drying the collected solvent in the eluent to obtain the o-methoxybenzaldehyde.
Optionally, the eluting eluent is a mixture of petroleum ether and ethyl acetate; the volume ratio of the petroleum ether to the ethyl acetate is 10: 1.
Compared with the prior art, the preparation method of o-methoxybenzaldehyde has the following advantages:
1. the invention takes simple and easily obtained benzaldehyde derivatives and anhydrous methanol as initial raw materials, takes palladium acetate as a catalyst, is matched with an oxidant, a solvent and an aniline ligand which can be condensed with aldehyde groups of the benzaldehyde derivatives to form a transient oriented group, and selectively carries out methoxylation reaction at the ortho position of the aldehyde groups of the benzaldehyde derivatives while the benzaldehyde derivatives and the anhydrous methanol are condensed with the aldehyde groups of the benzaldehyde derivatives to form the transient oriented group, so that the prepared o-methoxybenzaldehyde has higher yield and purity, and the yield can reach 67%.
2. The invention takes palladium acetate as a catalyst, and selectively carries out methoxylation reaction on the ortho position of the aldehyde group of the benzaldehyde derivative while condensing the benzaldehyde derivative and anhydrous methanol on the aldehyde group of the benzaldehyde ligand and the benzaldehyde derivative to form an instant guide group, so that the whole preparation process is simple and easy to operate, the time required by the whole reaction is shortened, the production efficiency is greatly improved, the reaction temperature and the solvent consumption of the invention are favorably reduced, the whole post-treatment process is greatly simplified, and the industrial production is easy. In addition, when dichloromethane is used as a solvent, the invention has low harm to human bodies, and after the dichloromethane invades into the bodies, the dichloromethane is mainly metabolized in the liver and is excreted quickly. Meanwhile, the invention adopts column chromatography for purification, greatly reduces the pressure on the environment and is beneficial to further improving the purity of the product.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a hydrogen spectrum of o-methoxybenzaldehyde prepared in example 1 of the present invention;
FIG. 2 is a carbon spectrum of o-methoxybenzaldehyde prepared in example 1 of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The prior o-methoxybenzaldehyde has complex synthesis method, large consumption of organic solvent, lower product yield and purity, large environmental protection pressure, therefore, on the basis of the prior o-methoxybenzaldehyde synthesis method, the invention takes benzaldehyde derivatives and anhydrous methanol as starting materials, uses palladium acetate as catalyst, and adds oxidant, solvent and aniline ligand capable of condensing with aldehyde group of benzaldehyde derivative to form instantaneous guide group, so that the benzaldehyde derivative and anhydrous methanol can be condensed with aldehyde group of benzaldehyde derivative to form instantaneous guide group, selectively carrying out methoxylation reaction at the ortho position of the aldehyde group of the benzaldehyde derivative, improving the yield and purity of the prepared o-methoxybenzaldehyde, and the reaction steps are simplified, the reaction time is shortened, the environmental protection pressure is reduced, and the popularization and application values of the catalyst are improved.
The reaction process of the methoxylation reaction of the invention is as follows:
wherein R is one of methyl, methoxy, phenyl, fluorine, chlorine and bromine, the aniline ligand is one of m-trifluoromethylaniline and o-trifluoromethylaniline, the oxidant is one of potassium persulfate and sodium persulfate, and the solvent is one of dichloromethane, 1, 2-dichloroethane and toluene.
The present invention will be described in detail below with reference to the drawings and examples.
Example 1
A preparation method of o-methoxybenzaldehyde specifically comprises the following steps:
1) 12.0mg (0.1mmol) of o-methylbenzaldehyde, 64.0mg (20.0mmol) of anhydrous methanol (MeOH), 2.25mg (0.01mmol) of palladium acetate (Pd (OAc))2) 54.0mg (0.2mmol) of potassium persulfate (K)2S2O8) 6.44mg (0.04mmol) of m-Trifluoromethylaniline (TDG) is mixed in 1ml of Dichloromethane (DCM), and then stirred on a magnetic stirrer at 60 ℃ for reaction for 24 hours, namely, the methoxylation reaction of the ortho position of aldehyde group in o-methyl benzaldehyde is carried out to obtain reaction liquid A, and the specification can be adopted in the reaction process
-254 TLC plate spot plate to track whether the reaction is complete;
2) filtering the reaction solution A, and adding saturated sodium bicarbonate aqueous solution and dichloromethane into filtrate B obtained by filtering to extract to obtain lower-layer extract C, wherein the volume ratio of the saturated sodium bicarbonate aqueous solution to the dichloromethane is 1: 3;
3) drying the extract C by using anhydrous sodium sulfate, removing water, filtering, adding silica gel powder into the filtrate D obtained by filtering, and spin-drying dichloromethane to obtain a mixture E containing o-methoxybenzaldehyde and silica gel powder, wherein the ratio of the using amount of the extract C to the using amount of the anhydrous sodium sulfate is 1L: 25g, namely the mass of the anhydrous sodium sulfate required for drying the extract C of 1L is 25g, and the mass of the silica gel powder is 30-40 times of the mass of a solute in the filtrate D;
4) the mixture E was separated and purified by column chromatography to give 10.1mg of o-methoxybenzaldehyde (2-methoxy-6-methylbenzaldehyde) in a calculated yield of 67%.
In this embodiment, the column chromatography separation and purification of mixture E specifically includes the following steps:
mixing silica gel powder with petroleum ether into paste by wet column packing method, and pouring into chromatographic column with diameter of 3.5cm and height of 30 cm;
adding petroleum ether into the chromatographic column, and pressurizing by using an air pump until the flow rate is constant, so that the volume of the column bed is compressed to 9/10 which is equal to the original volume of the column bed;
loading the mixture E into a chromatographic column by adopting a dry loading method, developing and eluting by adopting an eluent, continuously dotting a plate through a thin-layer chromatography in the elution process, observing whether a target product is eluted, collecting eluent of the target product after the elution is finished, combining the collected eluents, and then, spin-drying the solvent in the eluent to obtain the o-methoxybenzaldehyde, wherein the eluent is a mixture of petroleum ether and ethyl acetate; the volume ratio of the petroleum ether to the ethyl acetate is 10: 1.
10mg of o-methoxybenzaldehyde from example 1 were dissolved in 0.5m of L deuterated chloroform (CDCl)3) The nuclear magnetic resonance hydrogen spectrum and the carbon spectrum are tested, and the test results are respectively shown in fig. 1 and fig. 2.
As can be seen from fig. 1, the hydrogen spectrum of the o-methoxybenzaldehyde of example 1 of the present invention contains peaks of 1H NMR (500MHz, CDCl3)10.63(s,1H),7.37(t, J ═ 8.0Hz,1H),6.82(d, J ═ 8.4Hz,1H),6.79(d, J ═ 7.6Hz,1H),3.88(s,3H), and 2.56(s,3H), where 10.63(s,1H) is H on the aldehyde group, 6.82(d, J ═ 8.4Hz,1H) is H on the benzene ring located in the ortho position to the methoxy group, 6.79(d, J ═ 7.6Hz,1H) is H on the benzene ring located in the ortho position to the methyl group, 7.37(t, J ═ 8.0Hz,1H) is H on the benzene ring in the para position to the aldehyde group, 3.88(s,3H) is H, 3H (s,3H) is methyl group.
As can be seen from FIG. 2, the present inventionThe carbon spectrum of o-methoxybenzaldehyde of example 1 contains13C NMR(126MHz,CDCl3)192.32,163.17,142.03,134.43,124.09,123.36,109.05,55.77,21.44, wherein 192.32 is the C on aldehyde, 163.17,142.03,134.43,124.09,123.36,109.05 is the C on benzene ring, 55.77 is the C on methoxy, 21.44 is the C on methyl.
As is clear from the analysis of the peaks in the spectra of fig. 1 and 2, the synthesized substance in this example was o-methoxybenzaldehyde.
The reaction sequence of the methoxylation reaction of the embodiment is as follows:
wherein R is methyl; the structural formula of TDG is:
the molar ratio of the benzaldehyde derivative, the anhydrous methanol, the palladium acetate, the oxidant and the aniline ligand is 1: 20: 0.1: 2: 0.4. When 0.1mmol of benzaldehyde derivative was added, 1ml of the solvent was added.
Example 2
This example differs from example 1 in that: in this example, the aniline ligand that forms the transient targeting group by condensation with the aldehyde group in o-methylbenzaldehyde is o-trifluoromethylaniline, the amount of o-trifluoromethylaniline used is 6.44mg (0.04mmol), and the composition of other preparation raw materials and the preparation process of o-methoxybenzaldehyde are the same as those in example 1.
The amount of o-methoxybenzaldehyde obtained in this example was 6.75mg, which was calculated to give a yield of 45%.
Example 3
This example differs from example 1 in that: in this example, the oxidant was sodium persulfate in an amount of 47.6mg (0.2mmol), and the composition of other raw materials for preparation and the process for preparing o-methoxybenzaldehyde were the same as in example 1.
The amount of o-methoxybenzaldehyde obtained in this example was 7.35mg, and the calculated yield was 49%.
Example 4
This example differs from example 1 in that: in this example, the solvent was 1, 2-dichloroethane, and the amount of 1ml, and the composition of the raw materials for the preparation and the preparation of o-methoxybenzaldehyde were the same as those in example 1.
The amount of o-methoxybenzaldehyde obtained in this example was 9.45mg, which was calculated to give a yield of 63%.
Example 5
This example differs from example 1 in that: the reaction temperature of the methoxylation reaction in this example was 40 ℃, and the composition and preparation process of each raw material in this example were the same as those in example 1.
The amount of o-methoxybenzaldehyde obtained in this example was 5.55mg, which was calculated to give a yield of 37%.
Example 6
This example differs from example 1 in that: the reaction temperature of the methoxylation reaction in this example was 80 ℃, and the composition and preparation process of each raw material in this comparative example were the same as those in example 1.
The amount of o-methoxybenzaldehyde obtained in this example was 9.3mg, and the calculated yield was 62%.
Example 7
This example differs from example 1 in that: in this example, the solvent was toluene, the amount of toluene was 1ml, the reaction temperature of the methoxylation reaction was 40 ℃, and the composition of other raw materials and the process for preparing o-methoxybenzaldehyde were the same as in example 1.
The amount of o-methoxybenzaldehyde obtained in this example was 4.5mg, which was calculated to give a yield of 30%.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A preparation method of o-methoxybenzaldehyde is characterized by comprising the following steps:
1) mixing benzaldehyde derivatives, absolute methanol, palladium acetate, an oxidant and an aniline ligand in a solvent, and then carrying out methoxylation reaction at a certain temperature to obtain a reaction liquid A;
2) filtering the reaction liquid A, and extracting a filtrate B obtained by filtering with an extracting agent to obtain a lower layer extract C;
3) drying the extract C by using a drying agent, removing water, filtering, adding silica gel powder into the filtrate D obtained by filtering, and spin-drying the dichloromethane to obtain a mixture E;
4) separating and purifying the mixture E by chromatography to obtain o-methoxybenzaldehyde;
the molar ratio of the benzaldehyde derivative, the anhydrous methanol, the palladium acetate, the oxidant and the aniline ligand in the step 1) is 1: 15-20: 0.1: 2: 0.4;
the reaction temperature of the methoxylation reaction in the step 1) is 60-80 ℃, and the reaction time is 18-32 h;
the substituent on the benzaldehyde of the benzaldehyde derivative in the step 1) is one of methyl, methoxy, phenyl, fluorine, chlorine and bromine, the aniline ligand is one of m-trifluoromethylaniline and o-trifluoromethylaniline, the oxidant is one of potassium persulfate and sodium persulfate, and the solvent is one of dichloromethane, 1, 2-dichloroethane and toluene.
2. The method for preparing o-methoxybenzaldehyde according to claim 1, wherein the ratio of the amount of the benzaldehyde derivative to the amount of the solvent in step 1) is 1 mol: 10 to 15L.
3. The method for preparing o-methoxybenzaldehyde according to claim 1, wherein the extractant in step 2) is a mixture of saturated aqueous sodium bicarbonate and dichloromethane; the volume ratio of the saturated sodium bicarbonate aqueous solution to the dichloromethane is 1: 2-3.
4. The method for preparing o-methoxybenzaldehyde according to claim 1, wherein the drying agent in step 3) is anhydrous sodium sulfate, and the ratio of the amount of the extract C to the amount of the drying agent is 1L: 25 g.
5. The method for preparing o-methoxybenzaldehyde according to claim 1, wherein the chromatography in step 4) comprises column chromatography.
6. The method for preparing o-methoxybenzaldehyde according to claim 5, wherein the column chromatography comprises the steps of:
mixing silica gel powder with petroleum ether to obtain paste, and pouring into chromatographic column;
adding petroleum ether to the column and pressurizing until the flow rate is constant, so that the volume of the column bed is compressed to 9/10 which is equal to the original volume of the column bed;
and (3) placing the mixture E in a chromatographic column by adopting a dry method for sample loading, developing and eluting, after the elution is finished, point-collecting eluent of a target product, and then, spin-drying the collected solvent in the eluent to obtain the o-methoxybenzaldehyde.
7. The method for preparing o-methoxybenzaldehyde according to claim 6, wherein the eluent for elution is a mixture of petroleum ether and ethyl acetate; the volume ratio of the petroleum ether to the ethyl acetate is 10: 1.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0709361B1 (en) * | 1994-10-24 | 1999-02-03 | Rhodia Chimie | Process for the preparation of isovanilline |
| CN104447246A (en) * | 2014-11-04 | 2015-03-25 | 南京工业大学 | Method for preparing o-methoxybenzaldehyde by use of micro-reaction device |
| CN105130773A (en) * | 2015-07-17 | 2015-12-09 | 天宁香料（江苏）有限公司 | Preparation method of p-methoxybenzaldehyde |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0709361B1 (en) * | 1994-10-24 | 1999-02-03 | Rhodia Chimie | Process for the preparation of isovanilline |
| CN104447246A (en) * | 2014-11-04 | 2015-03-25 | 南京工业大学 | Method for preparing o-methoxybenzaldehyde by use of micro-reaction device |
| CN105130773A (en) * | 2015-07-17 | 2015-12-09 | 天宁香料（江苏）有限公司 | Preparation method of p-methoxybenzaldehyde |
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