阅读说明：本技术 一种制备2,6-二甲氧基-4-乙烯基苯酚的方法 (Method for preparing 2, 6-dimethoxy-4-vinylphenol ) 是由 黄凤洪 从艳霞 李文林 刘昌盛 郑畅 周琦 万楚筠 郑明明 魏芳 于 2019-09-16 设计创作，主要内容包括：本发明涉及一种制备2,6-二甲氧基-4-乙烯基苯酚的原料和方法,属于食品化学合成与加工技术领域。所述方法包括：a)以芥子酰苹果酸酯为原料；b)经过加热处理得到含2,6-二甲氧基-4-乙烯基苯酚的混合物；c)经分离纯化得到高纯度的2,6-二甲氧基-4-乙烯基苯酚。该制备方法灵活简单、安全、环保,得到的产物纯度高。(The invention relates to a raw material and a method for preparing 2, 6-dimethoxy-4-vinylphenol, belonging to the technical field of chemical synthesis and processing of foods. The method comprises the following steps: a) using sinapoyl malate as a raw material; b) heating to obtain a mixture containing 2, 6-dimethoxy-4-vinylphenol; c) separating and purifying to obtain the high-purity 2, 6-dimethoxy-4-vinylphenol. The preparation method is flexible, simple, safe and environment-friendly, and the obtained product has high purity.)

1. A method for preparing 2, 6-dimethoxy-4-vinylphenol is characterized by comprising the following steps:

1) taking sinapoyl malate as a raw material, dissolving the raw material in methanol, drying under reduced pressure to obtain a mixture, and heating the mixture in a thermal environment for reaction;

2) after the heating reaction is finished, obtaining a mixture containing 2, 6-dimethoxy-4-vinylphenol, extracting the mixture containing 2, 6-dimethoxy-4-vinylphenol by a solvent, and carrying out reduced pressure drying treatment;

3) dissolving the dried product obtained in the step 2) by methanol, injecting the dissolved product into a preparative liquid chromatograph for elution, and collecting eluent when a chromatographic peak of 2, 6-dimethoxy-4-vinylphenol appears through ultraviolet on-line detection;

4) drying the eluent obtained in the step 3) to obtain white powder of the 2, 6-dimethoxy-4-vinylphenol.

2. The method of claim 1, wherein the thermal environment in step 1) is provided by conventional resistance heating or microwave heating.

3. The method as claimed in claim 2, wherein the ordinary resistance heating is selected from air convection heat transfer, oil bath heat transfer or other medium heat transfer, and the temperature of the ordinary resistance heating is 120-220 ℃ and the heating time is 1-30 min.

4. The method as claimed in claim 2, wherein the microwave heating is performed at a fixed power or a fixed temperature, and the fixed power is 400-1200W; the fixed temperature is 120-220 ℃; the heating time is 3-30 min.

5. The method of claim 1, wherein the solvent used in step 2) is an organic solvent with a polarity ranging from 0.06 to 6.6, and the solvent extraction is performed 3 to 5 times.

6. The method for preparing 2, 6-dimethoxy-4-vinyl phenol as claimed in claim 1, wherein the reduced pressure drying in step 1) and step 2) is selected from one of vacuum drying, rotary evaporation and freeze drying.

7. The method for preparing 2, 6-dimethoxy-4-vinyl phenol according to claim 1, wherein the preparative liquid chromatograph in step 3) is eluted as: the chromatographic column adopts a reversed phase C18 column, the mobile phase A is 100% ultrapure water, the mobile phase B is 100% chromatographically pure methanol, and the elution is carried out at an isocratic rate of 60-90% of the mobile phase A.

8. The method for preparing 2, 6-dimethoxy-4-vinyl phenol as claimed in claim 1, wherein the drying in step 4) is performed by a freeze dryer under the following conditions: vacuum degree of 0.3-1.0mbar, cold trap temperature of-48 deg.C, shelf temperature of 0-5 deg.C, and drying time of 1-48 h.

Technical Field

The invention relates to the technical field of food chemical synthesis and processing, in particular to a method for preparing 2, 6-dimethoxy-4-vinylphenol.

Background

The 2, 6-dimethoxy-4-vinylphenol is easily dissolved in grease, has strong free radical scavenging capacity and oxidation resistance, and can delay senility and prevent diseases such as tumors, heart and cerebral vessels and the like. The 2, 6-dimethoxy-4-vinylphenol exists in a limited amount in plants and is obtained by a chemical synthesis method. Sinha et al reported microwave synthesis of 2, 6-dimethoxy-4-vinylphenol from syringaldehyde as the starting material. Harbaum-Piayda et al reported a process for the preparation of 2, 6-dimethoxy-4-vinylphenol by hydrolysis starting from 4-acetoxy-3, 5-dimethoxystyrene. The prior research shows that the sinapic acid generates decarboxylation reaction under the heating action to generate the 2, 6-dimethoxy-4-vinylphenol. The patent CN105815779B carries out enzymolysis reaction on rapeseed meal, so that sinapine existing in the rapeseed meal in a large amount is converted into sinapic acid; and then the sinapic acid is utilized to be converted into a target product 2, 6-dimethoxy-4-vinylphenol through thermal decarboxylation. Bernini et al report a microwave synthesis of 2, 6-dimethoxy-4-vinylphenol from sinapic acid in the presence of 1, 8-diazabicyclo [5.4.0] -7-undecene in the presence of hydroquinone. Patent CN104496768A uses sinapic acid as raw material, alumina as solid phase carrier, and carries out thermal decarboxylation reaction under the condition of alkaline catalyst and microwave assistance, polymerization inhibitor is added to reduce and prevent the polymerization of the synthesized product, after the reaction is finished, the alkaline catalyst in the reaction system is neutralized, then the synthesized product is extracted by organic solvent, and after washing and drying, the synthesized product is purified by preparative liquid chromatography, and then high-purity 2, 6-dimethoxy-4-vinylphenol is obtained by vacuum drying.

The existing preparation method mostly takes sinapic acid as a raw material, and 2, 6-dimethoxy-4-vinylphenol needs to be prepared under the action of an organic solvent, a catalyst and a blocking agent. However, no report is available on the direct preparation of 2, 6-dimethoxy-4-vinylphenol from sinapoyl malate as a starting material. The method takes sinapoyl malate as a raw material, does not need to add a solvent, a catalyst and a blocking agent, adopts a direct heating mode to prepare the 2, 6-dimethoxy-4-vinylphenol, and has the advantages of simple process, environmental protection and safe product. Sinapoyl malate is mostly present in plants, most commonly found in the cruciferous crop rape, and is distributed mainly in fruits and rhizomes. The most common processing and treating means of rapeseeds are heat treatment, such as heat drying, heat seed frying, hot pressing, high-temperature deodorization and the like. The simple heat treatment mode can convert the sinapoyl malate into the 2, 6-dimethoxy-4-vinylphenol, and has important significance for improving the comprehensive value of the rapeseed.

The invention provides a novel method for preparing 2, 6-dimethoxy-4-vinylphenol on one hand; on the other hand, a new method is provided for improving the added value of the plant raw material rich in sinapoyl malate.

Disclosure of Invention

In view of the above, the invention provides a method for preparing 2, 6-dimethoxy-4-vinylphenol, which is simple to operate and is environment-friendly, without adding a solvent and a catalyst.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing 2, 6-dimethoxy-4-vinylphenol, which comprises the following steps:

1) taking sinapoyl malate as a raw material, dissolving the raw material in methanol, drying under reduced pressure to obtain a mixture, and heating the mixture in a thermal environment for reaction;

2) after the heating reaction is finished, obtaining a mixture containing 2, 6-dimethoxy-4-vinylphenol, extracting the mixture containing 2, 6-dimethoxy-4-vinylphenol by a solvent, and carrying out reduced pressure drying treatment;

3) dissolving the dried product obtained in the step 2) by methanol, injecting the dissolved product into a preparative liquid chromatograph for elution, and collecting eluent when a chromatographic peak of 2, 6-dimethoxy-4-vinylphenol appears through ultraviolet on-line detection;

4) drying the eluent obtained in the step 3) to obtain white powder of the 2, 6-dimethoxy-4-vinylphenol.

Preferably, the thermal environment in step 1) is provided by common resistance heating or microwave heating.

Preferably, the ordinary resistance heating is selected from air convection heat transfer, oil bath heat transfer or other medium heat transfer modes, the temperature of the ordinary resistance heating is 120-.

Preferably, the temperature of the ordinary resistance heating is 160-200 ℃, and the heating time is 3-20 min.

Preferably, the microwave heating is performed at a fixed power or a fixed temperature, wherein the fixed power is 400-1200W; the fixed temperature is 120-220 ℃, and the microwave heating time is 3-30 min.

Preferably, the fixed power is 500-; the fixed temperature is 160-.

Preferably, the product conversion in step 1) above is 10-65%.

Preferably, the solvent in the step 2) is an organic solvent with a polarity ranging from 0.06 to 6.6, and the solvent extraction needs to be performed 3 to 5 times.

Preferably, the organic solvent is one of ethyl acetate, butyl butyrate, ethyl ether and n-hexane.

Preferably, the reduced pressure drying in step 1) and step 2) is selected from one of vacuum drying, rotary evaporation and freeze drying.

Preferably, the drying under reduced pressure is rotary evaporation drying.

Preferably, the elution in step 3) by preparative liquid chromatography is as follows: the chromatographic column adopts a reversed phase C18 column, the mobile phase A is 100% ultrapure water, the mobile phase B is 100% chromatographically pure methanol, and the elution is carried out at an isocratic rate of 60-90% of the mobile phase A.

Preferably, the drying in the step 4) is performed by a freeze dryer, and the drying conditions are as follows: vacuum degree of 0.3-1.0mbar, cold trap temperature of-48 deg.C, shelf temperature of 0-5 deg.C, and drying time of 1-48 h.

Preferably, the conversion rate of the 2, 6-dimethoxy-4-vinyl phenol prepared by the invention is 10-65%, and the purity is 95-99%.

The 2, 6-dimethoxy-4-vinylphenol prepared according to the invention is dissolved in methanol, and the content and purity are calculated by the liquid chromatography peak area. The yield of the invention is calculated according to the following formula:

conversion (%) -. 2, 6-dimethoxy-4-vinylphenol gives a molar mass/(1-residual sinapoyl malate) x 100%.

Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:

1. the invention provides a new method for preparing 2, 6-dimethoxy-4-vinylphenol by taking sinapoyl malate as a raw material;

2. the method only needs simple heating treatment without adding a solvent and a catalyst, is simple to operate, green and environment-friendly, wide in application range and high in yield and product purity;

3. the invention adopts the preparative liquid chromatography to purify the target product, and has the advantages of high product purity and small pollutant;

4. the invention adopts a freeze drying mode to dry the product after chromatographic purification, which is beneficial to protecting the biological activity of the target product.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a flow chart of the present invention for preparing 2, 6-dimethoxy-4-vinylphenol using sinapoyl malate as a raw material.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.