CN114044738B - Method for preparing pentadiene aldehyde by aldol condensation - Google Patents
Method for preparing pentadiene aldehyde by aldol condensation Download PDFInfo
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- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
- C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
- C07C45/68—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms
- C07C45/72—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups
- C07C45/74—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups combined with dehydration
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- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/81—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C45/82—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
- C07C45/84—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation by azeotropic distillation
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Abstract
The invention provides a preparation method of pentadiene aldehyde, belonging to the field of organic synthesis. In the method, quaternary ammonium base/metal halide is used as a catalyst, so that acrolein and acetaldehyde undergo aldol condensation reaction under the action of an auxiliary agent to obtain pentadiene aldehyde. Compared with the traditional 1, 2-pentadiene isomerization and oxidation production process, the novel pentadiene aldehyde preparation process provided by the invention has the advantages of easily available raw materials, simple steps and high production efficiency, and is suitable for large-scale production of pentadiene aldehyde. Meanwhile, the quaternary ammonium base/metal halide catalyst and the auxiliary agent greatly reduce the Cannizzaro side reaction and the self-polymerization or copolymerization reaction, and improve the acrolein conversion rate and the selectivity of a target product.
Description
Technical Field
The invention relates to the field of organic synthesis, in particular to a method for preparing pentadiene aldehyde through aldol condensation.
Background
The aldehyde is a very important and diversified one of spices, particularly, various raw materials of unsaturated aldehyde family and bifunctional aldehyde family can be used for daily use chemicals and food essence, are mostly contained in products such as flowers, fruits, vegetables, meat, milk and the like, and have natural food aroma and taste. Pentadiene aldehyde is a food flavor allowed by the regulation of GB2760-1996, has obvious bouillon flavor, is commonly used for preparing meat flavor and flavoring flavor, and is added into final flavoring food at a concentration of about 0.2-38 mg/kg. In addition, glutarenal can also be oxidized to pentadienoic acid, reduced to pentadienol, or hydrogenated to valeraldehyde, which can be further used as a fragrance, rubber accelerator. At present, few reports are made about the synthetic method of pentadiene aldehyde, 1, 2-pentadiene is used as a raw material, the pentadiene aldehyde can be obtained through isomerization and oxidation, the synthetic process has low selectivity and complex synthesis.
The aldol condensation reaction is a reaction in which an alpha-hydrogen-containing compound such as aldehyde, ketone, carboxylic acid, ester, and the like undergoes nucleophilic addition with a carbonyl compound under the action of a catalyst to obtain a beta-hydroxy compound or is further dehydrated to obtain an alpha, beta-unsaturated aldehyde ketone or acid ester, and the condensation product can be further used for producing polymers such as perfumes, medicines, and the like. Aldol condensation reactions are typically carried out in the presence of strong acid or strong base catalysts, but mass production of strong acid and strong base has a significant negative impact on the environment and the catalyst is not recyclable. In addition, the use of strong acids and bases also imposes some harsh conditions on the reaction and not all types of starting materials can be used. The aldol condensation reaction is divided into two types, namely self-aldol condensation and cross-aldol condensation: two molecules of the same or different aldehyde/ketone may undergo an aldol condensation reaction, in fact the condensation of two molecules of aldehyde/ketone is usually accompanied by immediate dehydration to form an unsaturated aldehyde/ketone.
Patent CN101868440 discloses a novel catalyst for aldol condensation reaction, which makes aldehyde or ketone react in the presence of inorganic ammonium salt or its water/organic solution, the inorganic ammonium salt has catalytic efficiency equivalent to strong acid/strong base, and is environmentally friendly and capable of utilizing more sensitive substrate, but the method is not suitable for aldol condensation reaction in the unsaturated aldehyde/ketone field, and the α -hydrogen activity having unsaturated aldehyde/ketone needs to be activated to strengthen the aldol condensation reaction, improving the conversion efficiency.
Patent CN106008202 discloses a method for preparing 2, 2-dimethylolbutyric acid by catalyzing aldol condensation reaction, formaldehyde and n-butyraldehyde are taken as raw materials, and are subjected to aldol condensation reaction under the action of an alkaline anion exchange resin catalyst to generate 2, 2-hydroxymethylbutyraldehyde (DMB), and then are oxidized to generate 2, 2-dimethylolbutyric acid (DMBA); the method takes ion exchange resin as a catalyst, and has complex pretreatment process and low conversion rate; in addition, the self-polymerization of carbonyl compounds and the occurrence of side reactions cannot be controlled, and dimers and trimers of 2-ethylacrolein and 2, 2-dimethylolbutanal are formed at the same time, resulting in low selectivity of the target product.
Disclosure of Invention
The invention aims to provide a method for preparing pentadiene aldehyde by aldol condensation, which takes acetaldehyde and acrolein as raw materials to carry out aldol condensation reaction under the catalysis of metal halide and/or quaternary ammonium base to obtain the pentadiene aldehyde. The invention provides a new technological route for synthesizing pentadiene aldehyde, which has simple steps and high production efficiency, avoids the pollution of inorganic strong acid, strong alkali or heavy metal to the environment, can inhibit the occurrence of side reaction by using an amine auxiliary agent, effectively improves the selectivity of a target product, and is suitable for the large-scale production of pentadiene aldehyde.
In order to realize the purpose, the technical scheme of the invention is as follows:
a method for preparing pentadiene aldehyde by aldol reaction comprises the following steps: acrolein and acetaldehyde are taken as raw materials, and are subjected to aldol condensation reaction and dehydration under the action of a catalyst and an auxiliary agent to obtain pentadiene aldehyde.
In one embodiment, the reacting step comprises: dissolving a catalyst in a solvent, adding acrolein and an auxiliary agent in proportion, continuously dripping and adding acetaldehyde, and reacting under a certain condition to obtain pentadiene aldehyde;
the molar ratio of acrolein to acetaldehyde is 1.8 to 3, preferably 1 to 2.
The aldol condensation reaction temperature is 10-120 ℃, and preferably 50-80 ℃; the initial pressure of the reaction is 10 to 100bar, preferably 10 to 50bar; the reaction time is 0.5 to 24 hours, preferably 2 to 4 hours.
The amount of the catalyst is 0.5-5 wt% calculated by the mass of the acrolein.
The catalyst is one or more of copper chloride, copper bromide, chromium chloride, chromium bromide, iron (II, III) chloride, iron (II, III) bromide, vanadium chloride, vanadium bromide or dodecyl trimethyl ammonium hydroxide and tetraethylammonium hydroxide, and preferably one or more of copper bromide and tetraethylammonium hydroxide.
The auxiliary agent is one or more selected from diisobutylamine, triethylamine, cyclohexylamine and ethanolamine.
The dosage of the auxiliary agent is 1 to 5 percent of the mass of the acrolein, and the preferred dosage is 2 to 3 percent.
Due to the electron withdrawing effect of the carbonyl of the aldehyde containing the alpha-active hydrogen, the alpha-hydrogen proton has weak acidity, is easy to lose one hydrogen proton to form an electron delocalized carbanion, and is quickly subjected to nucleophilic addition with the carbonyl in another molecule of aldehyde to obtain one hydrogen proton to obtain unstable beta-hydroxyaldehyde, and further dehydrated to generate more stable alpha, beta-unsaturated aldehyde. Acid substances generated in the reaction process can greatly reduce the transfer rate of proton hydrogen in the reaction process, and the addition of the amine auxiliary agent can inhibit the generation of the acid substances and has little influence on the transfer rate of hydrogen protons, thereby greatly reducing the loss of alkaline active centers. In addition, the optimized metal halide or quaternary ammonium base is adopted as the catalyst, so that the number proportion of acid-base active centers can be effectively balanced, the catalytic activity and the high selectivity are ensured, and the strong alkaline environment is avoided, so that the self-polymerization and the copolymerization of aldehyde groups and the Cannizzaro side reaction are inhibited in the reaction.
The solvent is at least one selected from cyclohexane, ethylene glycol tertiary butyl ether, ethanol or dichloromethane.
The obtained aldol condensation reaction liquid is distilled to remove the solvent and the auxiliary agent, and the rest products and raw materials are separated by azeotropic distillation and adopt benzene as a water-carrying agent to obtain the product pentadiene aldehyde.
The reaction equation of the invention is as follows:
the invention has the positive effects that:
(1) The acetaldehyde and the acrolein are used as raw materials to prepare the pentadiene aldehyde, and the reaction steps are simple; the selectivity is high and can reach more than 99 percent, and the product yield is high.
(2) The method adopts the quaternary ammonium hydroxide/halogenated metal to catalyze the aldol reaction to prepare the pentadiene aldehyde, needs lower reaction temperature, reduces energy consumption, avoids the corrosion problem and the complex post-treatment process caused by the catalysis of inorganic strong acid and alkali, and is beneficial to catalyst recovery.
(3) The invention adopts the solvent, has good compatibility with the raw materials and the auxiliary agent, and the auxiliary agent and the solvent can be recycled, thereby reducing waste treatment.
Detailed Description
The present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.
The use of the drugs:
acrolein, acetaldehyde, group of national drugs;
metal halide catalyst, komeho;
quaternary ammonium bases, amine auxiliaries, glacier chemistry;
the gas chromatography test conditions of the present invention are as follows:
the instrument model is as follows: agilent 7890B
And (3) chromatographic column: DB-5 (30 m 0.25mm 0.25 μm)
Column temperature: the initial temperature is 40 deg.C, the temperature is raised to 150 deg.C at 10 deg.C/min, the temperature is maintained for 5min, and then the temperature is raised to 250 deg.C at 20 deg.C/min, the temperature is maintained for 10min
Sample inlet temperature: 200 deg.C
FID detector temperature: 250 deg.C
Split-flow sample injection, split ratio 50
Sample introduction amount: 2.0 μm
N 2 Flow rate: 40ml/min
H 2 Flow rate: 400ml/min.
Example 1
Adding a catalyst solution (10 wt% ethanol solution) containing 0.56g of tetraethylammonium hydroxide into a 500mL high-pressure reaction kettle, adding 56g of acrolein and 1.12g of diisobutylamine, uniformly mixing, starting stirring and controlling the temperature, wherein the initial reaction nitrogen pressure in the system is 20bar, and the reaction temperature is 60 ℃. And slowly pumping 44g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 2 hours of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal of the product, wherein the conversion rate of acrolein is 97.9%, the selectivity of the product is 98.5%, and the purity is 99.4%.
Product passing 1 H NMR(CDCl 3 ) And (3) confirming that: delta 9.68ppm (s, 1H), delta 7.43-7.47 ppm (d, 1H), delta 6.47-6.50 ppm (d, 1H), delta 6.26-6.29 ppm (d, 1H), delta 4.99-5.11 ppm (d, 2H), which is consistent with the structural formula of pentadiene aldehyde.
Example 2
A500 mL high-pressure reactor was charged with a catalyst solution (10 wt% ethanol solution) containing 1.68g of copper bromide, 56g of acrolein and 1.12g of ethanolamine were added and mixed uniformly, stirring and temperature control were started, the initial nitrogen pressure in the system was 30bar, and the reaction temperature was 60 ℃. And slowly pumping 66g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 2 hours of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal are carried out on the product, wherein the conversion rate of acrolein is 99.5%, the selectivity of the product is 99.8%, and the purity of the product is 99.9%.
Example 3
Adding a catalyst solution (10 wt% ethanol solution) containing 1.12g of tetraethylammonium hydroxide into a 500mL high-pressure reaction kettle, adding 56g of acrolein and 1.68g of triethylamine, uniformly mixing, starting stirring and controlling the temperature, wherein the initial reaction nitrogen pressure in the system is 30bar, and the reaction temperature is 60 ℃. And slowly pumping 44g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 2 hours of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal of the product, wherein the conversion rate of acrolein is 98.1%, the product selectivity is 99.1%, and the purity is 99.6%.
Example 4
A500 mL autoclave was charged with a catalyst solution (10 wt% dichloromethane solution) containing 0.56g dodecyltrimethylammonium hydroxide, 56g acrolein and 1.12g ethanolamine were added and mixed uniformly, stirring and temperature control were started, the initial nitrogen pressure in the system was 30bar, and the reaction temperature was 70 ℃. And (4) slowly pumping 44g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 1 hour of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal of the product, wherein the conversion rate of acrolein is 97.2%, the product selectivity is 99.0%, and the purity is 99.8%.
Example 5
A500 mL high-pressure reaction kettle is added with a catalyst solution (10 wt% dichloromethane solution) containing 1.12g tetraethylammonium hydroxide, 56g acrolein and 1.12g ethanolamine are added and mixed uniformly, stirring and temperature control are started, the reaction initial nitrogen pressure in the system is 40bar, and the reaction temperature is 70 ℃. And slowly pumping 66g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 1 hour of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal are carried out on the product, wherein the conversion rate of acrolein is 99.4%, the selectivity of the product is 98.9%, and the purity of the product is 99.7%.
Example 6
A500 mL autoclave was charged with a catalyst solution containing 1.68g of copper bromide (10 wt% dichloromethane solution), 56g of acrolein and 2.24g of diisobutylamine were added and mixed uniformly, stirring and temperature control were started, the initial reaction nitrogen pressure in the system was 30bar, and the reaction temperature was 70 ℃. And slowly pumping 77g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 2 hours of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal of the product, wherein the conversion rate of acrolein is 98.1%, the product selectivity is 99.4%, and the purity is 99.8%.
Comparative example 1
A500 mL autoclave was charged with a catalyst solution containing 1.12g NaOH (10 wt% dichloromethane solution), and 56g acrolein and 1.12g ethanolamine were added and mixed uniformly, stirring and temperature control were started, the initial reaction nitrogen pressure in the system was 40bar, and the reaction temperature was 70 ℃. And (4) slowly pumping 44g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 1 hour of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal of the product, wherein the conversion rate of acrolein is 78.1%, the selectivity of the product is 49.4%, and the purity is 84.8%.
Comparative example 2
A500 mL autoclave was charged with a catalyst solution (10 wt% dichloromethane solution) containing 1.12g tetraethylammonium hydroxide, 56g acrolein was added and mixed uniformly, stirring and temperature control were started, the initial nitrogen pressure in the system was 40bar, and the reaction temperature was 70 ℃. And (4) slowly pumping 44g of acetaldehyde into the reaction system, keeping the temperature and maintaining the pressure for 1 hour after about 1 hour of pumping is finished. After the reaction is finished, reaction liquid is collected, a solvent and an auxiliary agent are separated by distillation, and a pentadiene aldehyde product is obtained after azeotropic distillation, drying and water removal of the product, wherein the conversion rate of acrolein is 73.4%, the product selectivity is 77.6%, and the purity is 88.2%.
Claims (12)
1. A method for preparing pentadiene aldehyde by aldol reaction is characterized in that acrolein and acetaldehyde are used as raw materials, and the pentadiene aldehyde is obtained by aldol condensation reaction under the action of a catalyst and an auxiliary agent; the catalyst is selected from at least one of copper chloride, copper bromide, chromium chloride, chromium bromide, iron (II, III) chloride, iron (II, III) bromide, vanadium chloride, vanadium bromide or dodecyl trimethyl ammonium hydroxide and tetraethylammonium hydroxide, and the assistant is selected from at least one of diisobutylamine, triethylamine, cyclohexylamine and ethanolamine.
2. The method according to claim 1, wherein the molar ratio of the raw material acrolein and acetaldehyde is 1.
3. The method according to claim 2, wherein the molar ratio of the raw materials acrolein and acetaldehyde is 1.
4. The process according to claim 1, wherein the catalyst is used in an amount of 0.5 to 5wt% based on the mass of acrolein.
5. The method according to claim 1, wherein the amount of the auxiliary is 1 to 5% by mass based on the mass of acrolein.
6. The method according to claim 1, wherein the amount of the auxiliary is 2 to 3% by mass based on the mass of acrolein.
7. The method according to claim 1, wherein a solvent is further used, and the solvent is at least one selected from cyclohexane, ethylene glycol tertiary-butyl ether, ethanol, and dichloromethane.
8. The method according to any one of claims 1 to 7, wherein the aldol condensation reaction temperature is 10 to 120 ℃; the reaction time is 0.5-24 h.
9. The method according to claim 8, wherein the aldol condensation reaction temperature is 50 to 80 ℃; the reaction time is 2-4 h.
10. The process according to any one of claims 1 to 7, wherein the initial reaction pressure is 10 to 100bar.
11. The process according to claim 10, wherein the initial reaction pressure is 10 to 50bar.
12. The method as claimed in any one of claims 1 to 7, wherein the aldol condensation reaction solution is distilled to remove the solvent and the auxiliary agent, and the rest of the product and the raw material are separated by azeotropic distillation and water is removed by using benzene as a water-carrying agent to obtain the product pentadiene aldehyde.
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