Continuous condensation hydrogenation reaction method
By using NaOH and palladium carbon catalysts in the autoclave, combining hydrogen, dropwise aldehyde and acetone solution for dropwise addition and insulation reaction, the problem of the inability to perform hydroxyaldehyde condensation and selective hydrogenation in the prior art is solved, and high efficiency is achieved Industrial process for preparing high-purity methylheptanone.
Patent Information
- Application Number
- CN202311680977.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-08
- Publication Date
- 2024-12-13
AI Technical Summary
The existing continuous condensation and hydrogenation reactions cannot simultaneously perform aldol condensation and selective hydrogenation under alkaline conditions, resulting in inefficient process for preparing methylheptanone.
2-5% NaOH and palladium carbon catalyst were used in the autoclave, and hydrogen was added inward after heating and heating, mixed solution of aldehyde and acetone was added dropwise, and the dropwise addition and insulation reaction was carried out. The catalyst was then recovered by filtration and distilled to obtain high-purity acetonitrile. ylheptanone.
Under the presence of alkaline conditions and hydrogenation catalyst, aldol condensation and selective hydrogenation are achieved simultaneously, and a preparation process suitable for industrial production is designed, which improves the purity and yield of methylheptanone.
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of fine chemicals, in particular to a continuous condensation hydrogenation reaction method. Background Art
[0002] The common process for preparing methyl heptanone by continuous condensation hydrogenation reaction is carried out in two steps. In the first step, aldehyde and acetone are condensed into hydroxy ketone under catalytic conditions, and then dehydrated into unsaturated ketone. In the second step, the unsaturated ketone is reduced to saturated ketone with hydrogen.
[0003] The existing continuous condensation hydrogenation reaction cannot carry out aldol condensation and selective hydrogenation simultaneously under alkaline conditions, in the presence of a hydrogenation catalyst and hydrogen. Therefore, a continuous condensation hydrogenation reaction method is proposed to solve the above problem. Summary of the invention
[0004] The purpose of the present invention is to provide a continuous condensation hydrogenation reaction method to solve the problems raised in the above background technology.
[0005] To achieve the above object, the present invention provides the following technical solutions: A continuous condensation hydrogenation reaction method comprises the following steps: Step 1: Add 2-5% NaOH and palladium carbon catalyst into the autoclave and heat it up; Step 2: Add hydrogen to the autoclave to 1.5-2.5 MPa; Step 3: adding a mixed solution of aldehyde and acetone dropwise, and then performing a heat-keeping reaction after the addition is completed; Step 4: Filter and recover the catalyst for application, let the filtrate stand to separate the water phase, and then distill to obtain high-purity methyl heptanone.
[0006] Preferably, in step 1, the heating temperature is controlled between 110-150°C.
[0007] Preferably, in step 3, the time for adding the mixed solution of aldehyde and acetone dropwise is controlled to be completed between 2 and 5 hours.
[0008] Preferably, in step 3, the insulation reaction is controlled between 6 and 10 hours.
[0009] Preferably, in step three, the ratio of aldehyde to acetone in the mixed solution is (2-5):1.
[0010] Preferably, in step 2, when adding hydrogen into the autoclave, the gas in the autoclave is replaced with nitrogen three times, and with hydrogen three times, and then hydrogen is continuously added to increase the pressure.
[0011] Compared with the prior art, the beneficial effects of the present invention are: under alkaline conditions, in the presence of a hydrogenation catalyst and hydrogen, aldol condensation and selective hydrogenation are carried out simultaneously, and a preparation process suitable for industrial production is designed and optimized. DETAILED DESCRIPTION
[0012] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0013] The present invention provides a technical solution: A continuous condensation hydrogenation reaction method comprises the following steps: Step 1: Add 2-5% NaOH and palladium carbon catalyst into the autoclave and heat to 110-150°C; Step 2: Add hydrogen to the autoclave to 1.5-2.5 MPa; Step 3: adding a mixed solution of aldehyde and acetone dropwise for 2-5 hours, and then carrying out a heat preservation reaction for 6-10 hours after the addition is completed; Step 4: Filter and recover the catalyst for application, let the filtrate stand to separate the water phase, and then distill to obtain high-purity methyl heptanone.
[0014] The present invention will be further described below in conjunction with actual cases: Case 1: First, 90g of acetone, 50ml of 2% sodium hydroxide solution and 1.5g of 5% palladium / carbon were put into a high-pressure reactor and the gas in the reactor was replaced with nitrogen for 3 times and hydrogen for 3 times. The hydrogen was added to 2.0MPa, stirring was started, and the temperature was raised to 120°C. Then, a mixed solution of 258.3g of isovaleraldehyde and 90g of acetone was injected into the autoclave (about 3.5h). After the reaction was kept warm for about 8 hours, the temperature was lowered to below 40°C, the hydrogen was discharged, the nitrogen was replaced for 3 times, and the catalyst was filtered out for further application. After the filtrate was allowed to stand to separate the water phase, 364.3g of methyl heptanone with a purity of 98.7% was obtained by distillation, and the yield was 94.15%.
[0015] Case 2: First, 90g of acetone, 50ml of 3% sodium hydroxide solution and 1.5g of 5% palladium / carbon were put into a high-pressure reactor and the gas in the reactor was replaced with nitrogen for 3 times and hydrogen for 3 times. The hydrogen was added to 2.0MPa, stirring was started, and the temperature was raised to 130°C. Then, a mixed solution of 258.3g of isovaleraldehyde and 90g of acetone was injected into the autoclave (about 2.5h). After the reaction was kept warm for about 9 hours, the temperature was lowered to below 40°C, the hydrogen was discharged, the nitrogen was replaced for 3 times, and the catalyst was filtered out for further application. After the filtrate was allowed to stand to separate the water phase, 365.2g of methyl heptanone with a purity of 98.9% was obtained by distillation, and the yield was 94.57%.
[0016] Case 3: First, 90g of acetone, 60ml of 2% sodium hydroxide solution and 1.5g of 5% palladium / carbon were put into a high-pressure reactor and the gas in the reactor was replaced with nitrogen for 3 times and hydrogen for 3 times. The hydrogen was added to 2.0MPa, stirring was started, and the temperature was raised to 140°C. Then, a mixed solution of 258.3g of isovaleraldehyde and 90g of acetone was injected into the autoclave (about 3.0h). After the reaction was kept warm for about 7 hours, the temperature was lowered to below 40°C, the hydrogen was discharged, the nitrogen was replaced for 3 times, and the catalyst was filtered out for further application. After the filtrate was allowed to stand to separate the water phase, 363.7g of methyl heptanone with a purity of 99.1% was obtained by distillation, and the yield was 94.37%.
[0017] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A continuous condensation hydrogenation reaction method, characterized in that: The steps include: Step 1: Add 2-5% NaOH and palladium carbon catalyst into the autoclave and heat it up; Step 2: Add hydrogen to the autoclave to 1.5-2.5 MPa; Step 3: adding a mixed solution of aldehyde and acetone dropwise, and then performing a heat-keeping reaction after the addition is completed; Step 4: Filter and recover the catalyst for application, let the filtrate stand to separate the water phase, and then distill to obtain high-purity methyl heptanone.
2. A continuous condensation hydrogenation reaction method according to claim 1, characterized in that: In step 1, the heating temperature is controlled between 110-150°C.
3. A continuous condensation hydrogenation reaction method according to claim 1, characterized in that: In step 3, the time for adding the mixed solution of aldehyde and acetone dropwise is controlled to be completed between 2 and 5 hours.
4. A continuous condensation hydrogenation reaction method according to claim 1, characterized in that: In step 3, the heat preservation reaction is controlled between 6 and 10 hours.
5. A continuous condensation hydrogenation reaction method according to claim 1, characterized in that: In step 3, the ratio of aldehyde to acetone in the mixed solution is (2-5):
1.
6. A continuous condensation hydrogenation reaction method according to claim 1, characterized in that: In step 2, when adding hydrogen into the autoclave, the gas in the autoclave was replaced with nitrogen three times and hydrogen three times, and then hydrogen was continuously added to increase the pressure.