阅读说明：本技术 一种香茅醛水合反应制备羟基香茅醛的方法 (Method for preparing hydroxycitronellal through citronellal hydration reaction ) 是由 王联防 董菁 张永振 黎源 于斌成 于 2020-07-23 设计创作，主要内容包括：本发明公开一种香茅醛水合反应制备羟基香茅醛的方法。所述方法,包括以下步骤：在包裹Pd的多孔道分子筛催化剂和助剂作用下,香茅醛与水发生水合反应一步合成羟基香茅醛。所述的包裹Pd的多孔道分子筛催化剂,其中Pd/Si摩尔比为1:(10～200),Si/Al摩尔比为(50～100)：1。所述助剂为醚类物质,优选3-苯氧基甲苯。在多孔道固体催化剂和助剂作用下,原料香茅醛与水发生催化水合反应一步合成羟基香茅醛,具有高选择性、流程简化、三废少等优点。(The invention discloses a method for preparing hydroxycitronellal through citronellal hydration reaction. The method comprises the following steps: under the action of a Pd-coated porous molecular sieve catalyst and an auxiliary agent, citronellal and water undergo a hydration reaction to synthesize the hydroxycitronellal in one step. The Pd-coated porous molecular sieve catalyst has a Pd/Si molar ratio of 1 (10-200), and a Si/Al molar ratio of (50-100): 1. the auxiliary agent is an ether substance, and 3-phenoxytoluene is preferred. Under the action of the porous solid catalyst and the auxiliary agent, the raw material citronellal and water are subjected to catalytic hydration reaction to synthesize the hydroxycitronellal in one step, and the method has the advantages of high selectivity, simplified process, less three wastes and the like.)

1. A method for preparing hydroxycitronellal by citronellal hydration reaction comprises the following steps: under the action of a Pd-coated porous molecular sieve catalyst and an auxiliary agent, citronellal and water undergo a hydration reaction to synthesize the hydroxycitronellal in one step.

2. The method of claim 1, wherein the Pd-coated porous molecular sieve catalyst has a Pd/Si molar ratio of 1 (10-200), preferably a Pd/Si molar ratio of 1 (50-100), and a Si/Al molar ratio of (50-100): 1, preferably (60-80): 1.

3. The method of claim 1 or 2, wherein the Pd-coated multi-channel molecular sieve catalyst is prepared by a method comprising the steps of: 1) preparing Pd nano sol; 2) pd @ SiO₂Preparing; 3) and (3) preparing Pd @ ZSM.

4. A method according to any one of claims 1-3, wherein step 1) comprises the steps of:

a) mixing polyvinylpyrrolidone and Na₂PdCl₄And water according to the weight ratio of (2-10): 1: (50-100) preparing a solution according to the mass ratio, and fully stirring for 1-20 hours at the temperature of 5-30 ℃;

b) 2 to 10 times of Na₂PdCl₄Amount of substance NaBH₄Adding the solution of a) into the solution of a), fully stirring the solution for 2 to 20 hours at the temperature of 5 to 30 ℃, standing the solution for 10 to 24 hours, and filtering the solution to obtain the nano sol of the metal Pd.

5. The method according to any one of claims 1 to 4, wherein the step 2) comprises the steps of:

a1) respectively adding 10-50 times of Na₂PdCl₄Ethanol and 2-10 times of Na in mass₂PdCl₄Adding ammonia water of mass into the nano sol of the metal Pd, and fully stirring for 1-10 h at the temperature of 5-20 ℃;

b1) adding 10-200 times of Na₂PdCl₄Adding tetraethoxysilane of the amount of the substances into the mixture of a1), and fully stirring for 5-20 h at 5-30 ℃;

c1) drying the mixture obtained in b1) at 100-150 ℃ for 10-24 h to obtain Pd-coated SiO₂Is denoted as Pd @ SiO₂。

6. The method according to any one of claims 1 to 5, wherein the step 3) comprises the steps of:

a2) pd @ SiO with a certain mass₂AlOOH and tetrapropyl hydroxideMixing ammonium, and fully grinding for 1-10 h, wherein the Si/Al molar ratio is 50-100, and the tetrapropylammonium hydroxide and Pd @ SiO₂The mass ratio of (1-5) to 1;

b2) transferring the mixture obtained in the step a2) to a reaction kettle, and standing for 10-48 h at 150-250 ℃;

c2) separating and filtering the mixture obtained in the step b2), washing the obtained solid with deionized water, drying the solid at 100-200 ℃ for 5-20 h, and calcining the dried solid in a nitrogen atmosphere at 450-600 ℃ for 5-20 h to obtain the Pd-coated porous molecular sieve which is recorded as Pd @ ZSM.

7. The process according to any one of claims 1 to 6, characterized in that the auxiliary agent is an ether of formula I:

wherein R is₁And R₂Each independently is a linear or branched C1-C20 alkyl group, a substituted or unsubstituted aryl group; the auxiliary agent is preferably 3-phenoxytoluene.

8. A process according to any one of claims 1 to 7, wherein the molar amount of adjuvant is 0.1 to 10%, preferably 2 to 4%, of the molar amount of the starting material citronellal.

9. The method as claimed in any one of claims 1 to 8, wherein the space velocity of the raw material citronellal is 0.1 to 10h based on the mass of the catalyst Pd @ ZSM^-1Preferably 4 to 6 hours^-1。

10. The method according to any one of claims 1 to 9, wherein the hydration reaction temperature is 60 to 90 ℃, preferably 70 to 90 ℃.

Technical Field

The invention belongs to the field of organic synthesis, and particularly relates to a method for preparing hydroxyl citronellal by using citronellal as a raw material through a hydration method.

Background

The hydroxycitronellal has fine and pleasant flowery fragrance similar to lily and lily, is fresh, sweet and powerful, is widely applied to daily chemical essence, is a main component for preparing the lily type essence, can play a role in blending, and is one of important bulk spices.

At present, the synthesis method of the hydroxycitronellal mainly comprises the following two routes:

scheme 1 citronellal aldehyde group protection

The typical operation is that citronellal is used as a raw material, aldehyde groups are protected by sodium bisulfite (or secondary amine such as dimethylamine), then terminal double bonds are subjected to hydration reaction under an acidic condition, and finally hydroxyl citronellal is obtained through deprotection. The method is a mainstream production method in China at present, but a large amount of wastewater which is difficult to treat is generated in the production process, and the traditional process, namely sulfuric acid is adopted as an acidification catalyst in the acidification process, so that the method has high corrosion to equipment.

US3940446 discloses the preparation of hydroxycitronellal from citronellol by hydration of terminal double bond and dehydrogenation. The main catalyst for preparing hydroxycitronellal by dehydrogenation is metal and its oxide, such as copper, nickel, copper oxide, zinc oxide, etc. Because the reaction condition is harsh, the catalyst is easy to inactivate, the reaction conversion rate is not high, and the hydroxycitronellal is poor in acid resistance, alkali resistance and thermal stability, so that side reactions such as polymerization and the like are easily caused, the yield of the reaction and products at the later stage are seriously influenced, and the industrial popularization is not high.

The preparation routes of the hydroxycitronellal in the prior art are combined, so that obvious technical defects exist, and the development of a green hydroxycitronellal synthesis process is urgently needed.

Disclosure of Invention

The invention aims to provide a method for preparing hydroxycitronellal by citronellal hydration reaction. The method overcomes the defects in the prior art, simplifies the process flow, has high selectivity, can inhibit the generation of byproducts such as isopulegol and dimer, and has good industrialization prospect.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:

a method for preparing hydroxycitronellal by citronellal hydration reaction comprises the following steps: under the action of a Pd-coated porous molecular sieve catalyst and an auxiliary agent, citronellal and water undergo a hydration reaction to synthesize the hydroxycitronellal in one step.

The Pd-coated porous molecular sieve catalyst provided by the invention has a Pd/Si molar ratio of 1 (10-200), preferably a Pd/Si molar ratio of 1 (50-100), and a Si/Al molar ratio of (50-100): 1, preferably (60-80): 1.

In the present invention, the reaction equation is as follows:

in the invention, the preparation method of the Pd-coated porous molecular sieve catalyst comprises the following steps:

1) preparing Pd nano sol; 2) pd @ SiO₂Preparing; 3) and (3) preparing Pd @ ZSM.

As a preferred scheme, the step 1) comprises the following steps:

a) mixing polyvinylpyrrolidone and Na₂PdCl₄And water according to the weight ratio of (2-10): 1: (50-100) preparing a solution according to the mass ratio, and fully stirring for 1-20 hours at the temperature of 5-30 ℃;

b) 2 to 10 times of Na₂PdCl₄Amount of substance NaBH₄Adding the solution of a) into the solution of a), fully stirring the solution for 2 to 20 hours at the temperature of between 5 and 30 ℃, standing the solution for 10 to 24 hours, and filtering the solution to obtain a nano solution of the metal PdGluing;

as a preferable scheme, the step 2) comprises the following steps:

a1) respectively adding 10-50 times of Na₂PdCl₄Ethanol and 2-10 times of Na in mass₂PdCl₄Adding ammonia water (25-35 wt%) into the nanometer sol of the metal Pd, and fully stirring for 1-10 h at the temperature of 5-20 ℃;

b1) adding 10-200 times of Na₂PdCl₄Adding tetraethoxysilane of the amount of the substances into the mixture of a1), and fully stirring for 5-20 h at 5-30 ℃;

c1) drying the mixture obtained in b1) at 100-150 ℃ for 10-24 h to obtain Pd-coated SiO₂Is denoted as Pd @ SiO₂；

As a preferable scheme, the step 3) comprises the following steps:

a2) pd @ SiO with a certain mass₂Mixing AlOOH and tetrapropylammonium hydroxide, and then fully milling for 1-10 h, wherein the molar ratio of Si/Al is 50-100: 1, and the tetrapropylammonium hydroxide and Pd @ SiO₂The mass ratio of (1-5) to 1;

b2) transferring the mixture obtained in the step a2) to a reaction kettle, and standing for 10-48 h at 150-250 ℃;

c2) separating and filtering the mixture obtained in b2), washing the obtained solid with deionized water, drying at 100-200 ℃ for 5-20 h, calcining at 450-600 ℃ in a nitrogen atmosphere for 5-20 h to obtain a Pd-coated porous molecular sieve, which is marked as Pd @ ZSM, wherein the Si/Al molar ratio is (50-100): 1.

al is an electron-deficient atom, and when the element Al partially replaces SiO₂When the medium element Si forms a porous molecular sieve framework, the charge of the framework is unbalanced, and protons are needed to supplement the framework to achieve balance, so that acidity is generated. Therefore, different Si/Al molar ratios lead to different charge balance degrees in the pore channels and different acidity. We have found that when the Si/Al molar ratio is kept between 50 and 100, the distribution of acid sites in the pore channels and the acid strength are suitable for catalyzing the hydration reaction of citronellal, and neither too high nor too low Si/Al molar ratio is a good choice for the economy of the reaction process.

The Pd-coated porous molecular sieve catalyst prepared by the invention has rich pore structure and specific surface area as high as 600m²/g(N₂Adsorption and desorption test results), the pore size distribution range is 10-50 nm. In the microstructure, atomic Pd is uniformly embedded in the surface of the pore channel and is closely adjacent to framework elements Si and Al on the atomic level, and an active center is formed together. The three elements of Pd, Si and Al are uniformly distributed on the atomic level, a special microscopic charge environment is formed, the atomic Pd electron cloud distribution is influenced, the selective adsorption performance of C-C is obviously improved, the adsorption of C-O is further inhibited, the adsorption and activation of C-O in the adsorption stage are avoided, and a foundation is laid for improving the selective performance of hydration reaction. In addition, when the element Al partially replaces SiO in consideration of Al as an electron-deficient atom₂When the medium element Si forms a porous molecular sieve framework, the charge of the framework is unbalanced, and protons are needed to supplement the framework to achieve balance, so that acidity is generated. Therefore, when the raw materials citronellal and water enter the inside of the catalyst pore channel, Pd can obviously adsorb one end of citronellal containing C, and meanwhile, acidic protons are provided by the acidic sites generated by Si and Al around Pd, so that C is easily protonated and further undergoes a hydro-addition reaction with water, and finally the target product of hydroxycitronellal is formed.

It is well known that aldehyde groups undergo many side reactions in acidic media, including condensation, cyclization, and the like, to form by-products such as isopulegol and dimers. In order to further inhibit the catalytic action of C ═ O ends of the raw material citronellal by acidic protons on the inner wall of the pore channel, an auxiliary agent is introduced into the reaction system.

In the invention, the auxiliary agent is an ether substance with a structural formula I:

wherein R is₁And R₂Are each independently straightA chain or branched C1-C20 alkyl group, a substituted or unsubstituted aryl group. The auxiliary agent is preferably 3-phenoxytoluene. The auxiliary agent with the structural formula I is introduced into the reaction system, and in the pore channel, the oxygen-containing group of the auxiliary agent and C ═ O of citronellal have affinity with proper size, and because the auxiliary agent has a certain spatial structure, the probability that C ═ O is close to the inner wall of the pore channel is greatly reduced, so that unnecessary side reactions are less catalyzed by the acid sites on the surface of the inner wall, the generation of isopulegol and dimer is inhibited, and the selectivity of the reactions is obviously improved.

The method for preparing the hydroxycitronellal through the citronellal hydration reaction is preferably carried out in a fixed bed reactor.

According to the invention, the mass of the catalyst Pd @ ZSM is taken as a reference, and the space velocity of the raw material citronellal is 0.1-10 h^-1Preferably 4 to 6 hours^-1。

In the present invention, the molar amount of the auxiliary is 0.1 to 10%, preferably 2 to 4%, of the molar amount of the raw material citronellal.

In the invention, the molar ratio of water to the raw material citronellal is 1-10: 1, preferably 2-4: 1.

in the invention, the hydration reaction temperature is 60-90 ℃, and preferably 70-90 ℃.

In the invention, the conversion rate of citronellal is not less than 70%, and the selectivity of hydroxycitronellal is not less than 95%.

In the invention, the citronellal and the auxiliary agent which are not completely reacted in the reaction crude product can be recycled by rectification separation, so that the utilization rate of the citronellal and the auxiliary agent which are used as raw materials is further improved.

The hydration process of the present invention can be carried out by using a process known in the art, including but not limited to batch kettle, fixed bed, etc., preferably by using a fixed bed process, which can reduce the residence time of the raw materials and the product in the reactor, and is advantageous for improving the reaction performance.

The invention has the remarkable advantages that: under the action of a catalyst and an auxiliary agent, the one-step hydration reaction of citronellal and water is realized to prepare the hydroxyl citronellal, the process flow is obviously simplified, the reaction has higher selectivity, the generation of byproducts such as isopulegol and dimer can be inhibited, the process cost is obviously reduced, the three wastes are obviously reduced, and the requirement of green chemistry is met.

Detailed Description

The following examples are intended to illustrate the invention without limiting it in any way:

the analysis method comprises the following steps:

gas chromatograph: agilent7890, chromatography column wax (conversion, selectivity determination), injection port temperature: 300 ℃; the split ratio is 50: 1; the carrier gas flow is 52.8 ml/min; temperature rising procedure: at 150 ℃ for 10min, increasing to 260 ℃ at a rate of 10 ℃/min, for 5min, detector temperature: 280 ℃.

ICP (inductively coupled plasma emission spectrometer): the device is used for detecting Pd, Al and Si elements, the focal length is 0.38m, the echelle grating lines are 52.6/mm, the prism is 21 degrees, the charge injection type (CID) detector is a 512 multiplied by 512 detection unit, the wavelength range is 175 nm-1050 nm, the high-frequency generator is a high-frequency power 2.0KW, the number of turns of a working coil is 3, the frequency is 27.12MHZ, the glass concentric atomizer is a cyclone fog chamber, and the built-in 4-channel peristaltic pump is arranged. The analysis conditions were as follows: high-frequency power: 1.15KW, plasma gas flow: 15L/min, auxiliary airflow: 0.5L/min, peristaltic pump speed: 100rpm, observation height: 15mm, atomizing gas pressure: 0.22MPa, integration time: the long wave is more than 275nm 15S and the short wave is less than 275nm 25S.

BET(N₂Adsorption-desorption method) for characterizing the structure of the catalyst, F-Sorb 3400 type specific surface and pore size analyzer. Nitrogen is used as adsorbate, and helium or hydrogen is used as carrier gas.

The use of the medicine:

citronellal 98 wt%, pharmaceutical chemical company, Kyoho, Hubei;

sodium chloropalladate (Na)₂PdCl₄)98 wt%, Aladdin reagent, Inc.;

platinum chloride (PtCl)₂)98 wt%, Aladdin reagent, Inc.;

polyvinylpyrrolidone (PVP, K13-18), Aladdin reagent, Inc.;

sodium borohydride (NaBH)₄)98 wt%, Aladdin reagent, Inc.;

99.5% ethanol, alatin reagent, inc;

ammonia 30%, alatin reagent limited;

tetraethyl orthosilicate (TEOS) 99%, largeway technologies ltd;

boehmite (AlOOH) 99%, shanghai mclin biochemistry science and technology limited;

tetrapropylammonium hydroxide (TPAOH) 25%, shanghai mclin biochemistry science and technology limited;

98% of 3-phenoxytoluene, largeway technologies ltd;

5% Pd/C, Town Wanfeng catalyst Co., Ltd.