阅读说明：本技术 一种催化剂异构化顺式茴脑的方法 (Method for isomerizing cis-anethole by catalyst ) 是由 田沁东 于 2020-07-02 设计创作，主要内容包括：本方案公开了茴香脑制备技术领域的一种催化剂异构化顺式茴脑的方法,包括以下步骤：步骤一、将顺式茴脑加热至95～110℃；步骤二、将硫酸氢钠加入到加热后的顺式茴脑中得到混合物,对混合物加热8～10min至其温度为155～200℃,然后混合物保持恒温1～1.2h得到反应物；硫酸氢钠加热前与顺式茴脑的重量比为1～5:100；步骤三、将反应物冷却至常温并分液处理得到混合液,然后向混合液中加入碳酸钠溶液振荡反应5～6min得到中和液,将中和液分离得到上层的反式茴脑混合液；碳酸钠溶液与顺式茴脑的重量比为1～1.2:10。本方案采用硫酸氢钠作为催化剂,在硫酸氢钠的存在下,于150～200℃加热搅拌1h即可实现顺式茴脑的异构化,避免了使用氯化铑等稀有金属,大大降低了顺式茴脑异构化的成本。(The scheme discloses a method for isomerizing cis-anethole by using a catalyst, which belongs to the technical field of anethole preparation, and comprises the following steps: step one, heating cis-anethole to 95-110 ℃; step two, adding sodium bisulfate into the heated cis-anethole to obtain a mixture, heating the mixture for 8-10 min to the temperature of 155-200 ℃, and then keeping the mixture at the constant temperature for 1-1.2 h to obtain a reactant; the weight ratio of the sodium bisulfate to the cis-anethole before heating is 1-5: 100; step three, cooling the reactants to normal temperature and carrying out liquid separation treatment to obtain a mixed solution, then adding a sodium carbonate solution into the mixed solution, carrying out oscillation reaction for 5-6 min to obtain a neutralized solution, and separating the neutralized solution to obtain an upper-layer trans-anethole mixed solution; the weight ratio of the sodium carbonate solution to the cis-anethole is 1-1.2: 10. According to the scheme, sodium bisulfate is used as a catalyst, and the cis-anethole can be isomerized by heating and stirring for 1h at 150-200 ℃ in the presence of the sodium bisulfate, so that the use of rare metals such as rhodium chloride and the like is avoided, and the cost of cis-anethole isomerization is greatly reduced.)

1. A method for isomerizing cis-anethole by a catalyst is characterized by comprising the following steps: the method comprises the following steps:

step one, heating cis-anethole to 95-110 ℃;

step two, adding sodium bisulfate into the heated cis-anethole to obtain a mixture, heating the mixture for 8-10 min to the temperature of 155-200 ℃, and then keeping the mixture at the constant temperature for 1-1.2 h to obtain a reactant; the weight ratio of the sodium bisulfate to the cis-anethole before heating is 1-5: 100;

step three, cooling the reactants to normal temperature and carrying out liquid separation treatment to obtain a mixed solution, then adding a sodium carbonate solution into the mixed solution, carrying out oscillation reaction for 5-6 min to obtain a neutralized solution, and separating the neutralized solution to obtain an upper-layer trans-anethole mixed solution; the weight ratio of the sodium carbonate solution to the cis-anethole is 1-1.2: 10.

2. The method of claim 1, wherein the catalyst isomerizes cis anethole, and wherein the method comprises: the purity of the cis-anethole is more than 98%.

3. The method for the catalytic isomerization of cis anethole according to claim 2, wherein: the mass concentration of the sodium carbonate solution is 5%.

4. A method of isomerizing cis anethole using a catalyst according to any one of claims 1 to 3, wherein: the sodium bisulfate is sodium bisulfate powder which is sieved by a 100-mesh sieve.

5. The method of claim 4, wherein the catalyst isomerizes cis anethole, and wherein the method comprises: and (3) after the sodium bisulfate is sieved by a 100-mesh sieve, continuously drying for 2.5-3 hours at the temperature of 100-120 ℃ for later use.

6. The method of claim 5, wherein the catalyst isomerizes cis anethole, and wherein the method comprises: and in the second step, the mixture is continuously stirred while being heated.

7. The method for isomerizing cis anethole with the catalyst according to claim 5 or 6, wherein the catalyst comprises: in the second step, the mixture is heated to 155-190 ℃.

8. The method of claim 7, wherein the catalyst isomerizes cis anethole, and wherein the method comprises: in the second step, the weight ratio of the sodium bisulfate to the cis-anethole before heating is 1-2: 50.

Technical Field

The invention belongs to the technical field of anethole preparation, and particularly relates to a method for isomerizing cis-anethole by using a catalyst.

Background

Anethole (anethole), also known as anethole, estragole, anethole, etc., has a chemical name of 1-methoxy-4- (1-propenyl) -benzene, etc., and has cis-isomer and trans-isomer (i.e., cis-anethole and trans-anethole). The chemical structural formula of cis-anethole is as follows:the chemical structural formula of trans-anethole is as follows:

cis-anethole has toxicity and pungent odor, and the content of cis-anethole applied in the fields of food, cosmetics and the like cannot be more than 1 percent, and is generally required to be less than 0.2 percent.

Trans-anethole is one of the main components of many essential oils, and is widely used in the pharmaceutical, food, fragrance, and cosmetic industries. Current industrial processes for the synthesis of anethole form a mixture of cis and trans isomers from which the fractionation of trans anethole requires a high efficiency fractionation column. Meanwhile, in the primary fractionation, cis-anethole is almost a waste material in production because it is relatively rich and cannot be used due to its toxicity, pungent taste and unpleasant odor. Therefore, how to convert cis-anethole into valuable trans-anethole is a problem that needs to be solved currently.

Cis-anethole can be converted into trans-anethole under catalysis of rhodium chloride and other rhodium-containing compounds, such as anethole containing cis-anethole and trans-anethole at ratio of 25: 75 by adding rhodium chloride and anhydrous ethanol, and introducing N₂Displacing air, heating to 75 deg.C, refluxing for 8 hr, and converting the cis-inverse ratio of anethole to 5: 95. Evaporating to remove anhydrous ethanol, and vacuum fractionating at 30mmHg to obtain distillate with trans-anethole content of 100% when the distillation temperature is above 127 deg.C. However, rhodium metal, as a rare metal, is expensive and unavailable, so that the method is relatively expensive in industrial production and is not suitable for wide-range application.

Disclosure of Invention

The invention aims to provide a method for isomerizing cis-anethole by using a catalyst, so as to solve the problem of use of rare metals.

The method for isomerizing cis-anethole by using the catalyst comprises the following steps:

step one, heating cis-anethole to 95-110 ℃;

step two, adding sodium bisulfate into the heated cis-anethole to obtain a mixture, heating the mixture for 8-10 min to the temperature of 155-200 ℃, and then keeping the mixture at the constant temperature for 1-1.2 h to obtain a reactant; the weight ratio of the sodium bisulfate to the cis-anethole before heating is 1-5: 100;

step three, cooling the reactants to normal temperature and carrying out liquid separation treatment to obtain a mixed solution, then adding a sodium carbonate solution into the mixed solution, carrying out oscillation reaction for 5-6 min to obtain a neutralized solution, and separating the neutralized solution to obtain an upper-layer trans-anethole mixed solution; the weight ratio of the sodium carbonate solution to the cis-anethole is 1-1.2: 10.

The working principle and the beneficial effects of the scheme are as follows: the reaction of sodium bisulfate isomerization cis anethole mainly comprises a main reaction and a side reaction, and the specific reaction formula is as follows:

1. the main reaction: cis brain isomerization

2, side reaction:

2.1 Oxidation of Trans-anethole to Anisal

2.2 Oxidation of Trans-anethole to Methoxyphenylacetone

According to the scheme, sodium bisulfate is used as a catalyst, cis-anethole is heated to 95-110 ℃ before sodium bisulfate is added, and the cis-anethole and the sodium bisulfate react violently and can cause material flushing or explosion; sodium bisulfate is added at the temperature of 95-110 ℃, so that the condition is avoided. Sodium bisulfate is added at the temperature of 95-110 ℃, so that the sodium bisulfate is prevented from absorbing water and forming blocks due to low temperature, and the reaction efficiency between the sodium bisulfate and cis-anethole is ensured. In the presence of sodium bisulfate, the cis-anethole can be isomerized by heating and stirring at 150-200 ℃ for 1h, and the yield of the trans-anethole can reach 31-48%; avoids using rare metals such as rhodium chloride and the like, and greatly reduces the isomerization cost of cis-anethole. In addition, the isomer conversion rate is low when the reaction temperature is low at 155 ℃, and the processing cost is high in industrial application; when the temperature is higher than 200 ℃, when sodium carbonate is added subsequently to neutralize and clean the cis-anethole crude product, the anethole and the aqueous solution are not suitable for layering, so that the yield is low during liquid separation, and the temperature is high and is difficult to control in industrial production. According to the scheme, 155-200 ℃ is used as the reaction temperature, so that the yield of anethole is effectively improved, and the processing cost in industrial application is reduced. When the reactants are subjected to liquid separation treatment, the bottom layer is a solid polymer, the second layer is an aqueous sodium sulfate solution, the third layer is a mixed solution, the mixed solution contains cis-anethole, trans-anethole, sodium bisulfate, a posterior fragment and the like, and the posterior fragment refers to anisic aldehyde and/or anisic aldehyde generated during isomerization of the cis-anethole. The mixed solution of trans-anethole at the upper layer obtained by separating the neutralization solution contains cis-anethole, trans-anethole and posterior fragments.

Further, the purity of the cis-anethole is 98% or more. The cis-anethole with the purity of more than 98 percent is used as a raw material, so that the occurrence of side reactions can be greatly reduced during reaction, and further the loss of the cis-anethole is reduced.

Further, the mass concentration of the sodium carbonate solution is 5%. The excessive sodium bisulfate can be well neutralized by using a sodium carbonate solution with the mass concentration of 5 percent.

Further, the sodium bisulfate is sodium bisulfate powder which is sieved by a 100-mesh sieve. The sodium bisulfate is prepared into powder, so that the contact area between the sodium bisulfate and the cis-anethole is favorably increased, the reaction efficiency of the cis-anethole is improved, and the generation rate of the trans-anethole is favorably improved.

Further, after the sodium bisulfate is sieved by a 100-mesh sieve, the sodium bisulfate is continuously dried for 2.5-3 hours at the temperature of 100-120 ℃ for standby. Drying the sodium bisulfate is helpful for reducing the moisture in the sodium bisulfate, thereby being helpful for the subsequent reaction.

Further, in the second step, the mixture is continuously stirred while being heated. The reaction is facilitated by stirring.

Further, in the second step, the mixture is heated to 155-190 ℃. When the temperature of the mixture is heated to be lower than 155 ℃, the generation rate of trans-anethole is low; when the mixture is heated to a temperature higher than 190 ℃, the weight loss of the cis-anethole is large. And the mixture is heated to 155-190 ℃, so that the generation rate of trans-anethole can be better improved, the loss of cis-anethole can be reduced, and the method is more suitable for industrial production.

Further, in the second step, the weight ratio of the sodium bisulfate to the cis-anethole before heating is 1-2: 50. The weight ratio of the sodium bisulfate to the cis-anethole before heating is 1-2: 50, so that the generation rate of the trans-anethole can be better improved, the loss of the cis-anethole can be reduced, and the industrial production is more satisfied.

In the present application, the weight ratio of sodium bisulfate to cis-anethole before heating, and the weight ratio of sodium carbonate solution to cis-anethole; the weight of cis-anethole refers to the weight of the starting material cis-anethole.

Detailed Description

The following is further detailed by way of specific embodiments:

catalyst treatment: grinding sodium bisulfate crystals into powder, drying in a drying oven at 100 ℃ for 24h, taking out after drying, and sieving with a 100-mesh sieve; sieving with 100 mesh sodium bisulfate powder, and drying at 100 deg.C for 3 hr.