Preparation method of a-chloro-p-methylacetophenone
By adding chloroacetyl chloride dropwise at a lower temperature under the action of aluminum trichloride, combined with the filtration, rinsing, and drying processes of ether solvents, air exposure and the risk of air exposure in the preparation of a-chloro-p-methylacetophenone in the existing technology are solved. The problem of insufficient purity is eliminated, and a high-purity and safe preparation process is achieved.
Patent Information
- Application Number
- CN202411492741.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-24
- Publication Date
- 2025-01-24
AI Technical Summary
In the prior art, when preparing a-chloro-p-methylacetophenone, it is difficult to avoid air exposure and unorganized emissions, and it is difficult to achieve high purity after multiple crystallization.
Under the influence of aluminum chloride, cool down to less than 10 ° C, add chlorolychlchrium chlorine, reacts for 2 hours, and then hydrolyze, add ether solvents for filtering, rinsing, drying, and improve the purity of the product through heavy crystallization.
The high-purity A-chlorine substitution is prepared for methyllytone, avoiding multiple crystallization processes, ensuring the safety of the workshop environment, and reducing the risk of employees allergies.
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of preparation of α-chloro-p-methylacetophenone, in particular to a method for preparing α-chloro-p-methylacetophenone. Background Art
[0002] α-Chloro-p-methylacetophenone is a highly irritating substance. Slight exposure in the air will cause tears in the eyes and burning sensation on the skin, and skin contact will cause severe allergies. The purification method of the prior art is to improve the purity of the product by distillation, which is difficult to avoid exposure in the air or unorganized emission during the distillation process. At the same time, in order to ensure the purity of the product, the prior art requires multiple crystallizations, and the purity of the obtained product is still slightly insufficient. Summary of the invention
[0003] In order to solve the above problems, that is, to solve the problems raised by the above background technology, the present invention proposes a method for preparing α-chloro-p-methylacetophenone, and the specific technical scheme is as follows:
[0004] A preparation method of α-chloro-p-methylacetophenone is as follows: dissolving toluene in dichloroethane, cooling to below 10°C under the action of aluminum chloride, dropping chloroacetyl chloride, reacting for 2h, starting hydrolysis, adding to ice water, stirring fully and standing to separate, separating the dichloroethane layer, concentrating the remaining part, and obtaining a crude α-chloro-p-methylacetophenone; adding an ether solvent to the concentrated solution of the crude product, heating to 50-60°C, cooling to below 30°C after clarification, cooling and crystallizing, adding the mother liquor and the crystallized suspension to a three-in-one reactor, filtering in the reactor, adding an ether solvent to the filtrate for rinsing, filtering again, recovering the ether solvent, and drying to obtain refined α-chloro-p-methylacetophenone.
[0005] Specifically, the molar addition ratio of toluene, ethylene dichloride and aluminum chloride is 1:5.46:1.21.
[0006] Specifically, the amount of acetyl chloride added is 1.02 times the molar amount of toluene.
[0007] Specifically, the hydrolysis process is to add the reaction solution into twice the amount of ice water.
[0008] Specifically, the crude product has a content of 92-93%.
[0009] Specifically, in the step of adding an ether solvent to the crude product concentrate, the amount of the added ether solvent is 4-5 times that of the crude product concentrate.
[0010] Specifically, in the three-in-one reactor, the content of a-chloro-p-methylacetophenone is detected to be above 99.5%, and then the ether solvent is recovered.
[0011] The beneficial technical effect of the present invention is that the entire reaction process is a recrystallization process, and the purity of the product is made higher by using ether solvents, thereby avoiding the multiple crystallization processes in the prior art. At the same time, by adding dichloroethane solvent for heating and dissolving and then cooling for crystallization, a reaction kettle with filtering, rinsing and drying integrated is used for pressure filtration and drying, and then sealed packaging is performed, thereby avoiding direct contact between materials and people and unorganized emissions throughout the process, ensuring the environment of the workshop and reducing the risk of employee allergies. DETAILED DESCRIPTION
[0012] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.
[0013] A method for preparing α-chloro-p-methylacetophenone, the specific method is as follows:
[0014] Toluene was dissolved in dichloroethane, and the temperature was lowered to below 10°C under the action of aluminum chloride, wherein the molar addition ratio of toluene, dichloroethane and aluminum chloride was 1:5.46:1.21, chloroacetyl chloride was added dropwise, and the reaction was continued for 2 hours. The amount of acetyl chloride added was 1.02 times the molar amount of toluene, and it was added to 2 times the amount of ice water to start hydrolysis. After sufficient stirring, the mixture was allowed to stand for stratification, the dichloroethane layer was separated, and the remaining part was concentrated to obtain a crude product of α-chloro-p-methylacetophenone, with a crude content of 9 2-93%; add 4-5 times the amount of ether solvent to the crude concentrated solution, heat it to 50-60°C, cool it to below 30°C after clarification, cool it for crystallization, add the mother liquor together with the crystallized suspension into a three-in-one reaction kettle for filtration, rinsing and drying, filter it in the reaction kettle, add ether solvent to the filtrate for rinsing, filter it again, detect that the content of α-chloro-p-methylacetophenone is above 99.5%, dry it, and obtain the refined α-chloro-p-methylacetophenone product.
[0015] A batch of α-chloro-p-methylacetophenone was prepared by the prior art, and the obtained product was a comparative example. Three groups of α-chloro-p-methylacetophenone were prepared by the method described in this patent, and the obtained products were Examples 1-3. The above products were tested, and the test results were as follows:
[0016] Group Example 1 Example 2 Example 3 Comparative Example content(%) 98.05 99.57 99.52 99.53
[0017] At the same time, it can be seen from the above data that the content of α-chloro-p-methylacetophenone prepared by the method of the present invention is generally higher than that of the prior art, and the content of α-chloro-p-methylacetophenone prepared by the method can be guaranteed to be stable at more than 99.5%. In addition, because the filtering, rinsing and drying steps are carried out in a closed three-in-one reactor, the risk of product spillage is eliminated, preventing damage to the health of the staff.
[0018] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
[0019] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0020] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0021] The term "comprise" or any other similar term is intended to cover a non-exclusive inclusion, such that a process, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, article, or apparatus / device.
[0022] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.
Claims
1. A method for preparing α-chloro-p-methylacetophenone, characterized in that: The preparation method is as follows: dissolving toluene in dichloroethane, cooling to below 10°C under the action of aluminum chloride, dropping chloroacetyl chloride, reacting for 2 hours, starting hydrolysis, adding to ice water, stirring fully and standing to separate, separating the dichloroethane layer, and concentrating the remaining part to obtain a crude α-chloro-p-methylacetophenone; adding an ether solvent to the concentrated crude product, heating to 50-60°C, cooling to below 30°C after clarification, cooling and crystallizing, adding the mother liquor and the crystallized suspension to a three-in-one reactor, filtering in the reactor, adding an ether solvent to the filtrate for rinsing, filtering again, recovering the ether solvent, and drying to obtain refined α-chloro-p-methylacetophenone.
2. A method for preparing α-chloro-p-methylacetophenone according to claim 1, characterized in that: The molar addition ratio of toluene, ethylene dichloride and aluminum chloride is 1:5.46:1.
21.
3. A method for preparing α-chloro-p-methylacetophenone according to claim 1, characterized in that: The amount of acetyl chloride added is 1.02 times the molar amount of toluene.
4. A method for preparing α-chloro-p-methylacetophenone according to claim 1, characterized in that: The hydrolysis process is to add the reaction solution into twice the amount of ice water.
5. A method for preparing α-chloro-p-methylacetophenone according to claim 1, characterized in that: The crude product content is 92-93%.
6. A method for preparing α-chloro-p-methylacetophenone according to claim 1, characterized in that: In the step of adding an ether solvent to the crude product concentrate, the amount of the added ether solvent is 4-5 times that of the crude product concentrate.
7. A method for preparing α-chloro-p-methylacetophenone according to claim 1, characterized in that: In the three-in-one reactor, the content of a-chloro-p-methylacetophenone was detected to be above 99.5%, and then the ether solvent was recovered.