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CN-122010704-A - Method for preparing p-alkyl benzaldehyde

CN122010704ACN 122010704 ACN122010704 ACN 122010704ACN-122010704-A

Abstract

The application provides a method for preparing p-alkyl benzaldehyde. The method comprises the step of carrying out formylation reaction on carbon monoxide and alkylbenzene under catalysis of a hexafluorophosphoric acid solution to obtain the para-alkylbenzene formaldehyde, wherein the hexafluorophosphoric acid solution contains hexafluorophosphoric acid and hydrogen fluoride. The method can effectively avoid the occurrence of the disproportionation reaction of the raw material alkylbenzene, thereby simplifying the post-treatment process and improving the yield and purity of the paraalkylbenzene formaldehyde.

Inventors

  • LI GONGCHUN
  • Liu du
  • QIN XIAOKANG
  • HUANG XIAOWEI

Assignees

  • 九江天赐高新材料有限公司

Dates

Publication Date
20260512
Application Date
20241112

Claims (12)

  1. 1. A process for preparing a para-alkylbenzaldehyde comprising: And (3) carrying out formylation reaction on carbon monoxide and alkylbenzene under catalysis of a hexafluorophosphoric acid solution to obtain the para-alkylbenzene formaldehyde, wherein the hexafluorophosphoric acid solution contains hexafluorophosphoric acid and hydrogen fluoride.
  2. 2. The process according to claim 1, characterized in that the hexafluorophosphoric acid is obtained by the following method: And (3) carrying out a first reaction on hydrogen fluoride and phosphorus pentafluoride to obtain the hexafluorophosphoric acid.
  3. 3. The method of claim 2, wherein the molar ratio of hydrogen fluoride to phosphorus pentafluoride is not less than 5:1; And/or the temperature of the first reaction is-30 ℃ to 0 ℃.
  4. 4. The process of claim 2, wherein the formylation reaction is carried out in the same vessel as the first reaction.
  5. 5. The method of claim 4, wherein the molar ratio of said alkylbenzene to said phosphorus pentafluoride is from (0.5 to 1.5): 1.
  6. 6. The process according to claim 5, wherein the formylation reaction is carried out at a pressure in the range of from 1MPa to 10MPa; And/or the temperature of the formylation reaction is-30 ℃ to 0 ℃.
  7. 7. The method of claim 6, wherein the alkylbenzene has at least one primary alkyl group on the benzene ring.
  8. 8. The method of claim 7, wherein the primary alkyl group is of the formula: -CH 2 R, Wherein R comprises H or a straight, branched or cyclic saturated hydrocarbon group having 1 to 10 carbon atoms.
  9. 9. The method according to claim 1, wherein the formylation reaction further comprises, after the formylation reaction: distilling the solution obtained after the formylation reaction to obtain a first gas and a first liquid; and (3) carrying out first rectification treatment on the first liquid to obtain the paraalkylbenzaldehyde.
  10. 10. The method of claim 9, wherein the first gas comprises hydrogen fluoride and phosphorus pentafluoride; And/or the pressure of the distillation treatment is-0.1 MPa to 0MPa; And/or the distillation treatment temperature is 50-150 ℃; And/or the pressure of the first rectification treatment is-0.05 MPa to-0.1 MPa; And/or the temperature of the first rectification treatment is 100-200 ℃.
  11. 11. The method according to claim 1, wherein the formylation reaction further comprises, after the formylation reaction: washing the solution obtained after the formylation reaction to obtain an organic layer; And carrying out second rectification treatment on the organic layer to obtain the paraalkylbenzaldehyde.
  12. 12. The method of claim 11, wherein the washing treatment is performed with ice water; and/or the pressure of the second rectification treatment is-0.05 MPa to-0.1 MPa; And/or the temperature of the second rectification treatment is 100-200 ℃.

Description

Method for preparing p-alkyl benzaldehyde Technical Field The invention relates to the technical field of chemical industry, in particular to a method for preparing p-alkyl benzaldehyde. Background Para-alkyl benzaldehyde is a common chemical product or raw material and is widely applied to perfumes, medicines, agricultural chemicals and the like. At present, the formylation reaction of alkylbenzenes is a major difficulty in the preparation of alkylbenzaldehydes. There are two main methods reported in the prior art, one is to use hydrochloric acid-aluminum chloride as a catalyst, and the other is to use hydrogen fluoride-boron trifluoride as a catalyst. However, both of these methods have certain drawbacks. Among them, the former catalyst is difficult to recycle, and a large amount of waste is generated during the post-treatment, resulting in an increase in cost. The latter catalyst can induce the raw materials to generate disproportionation reaction, so that the post-treatment difficulty is increased, and the product yield is low. Therefore, it is important to find a more efficient and environmentally friendly preparation method. Disclosure of Invention The present application aims to solve at least one of the technical problems existing in the prior art to at least some extent. In a first aspect of the present application, the present application provides a process for preparing para-alkyl benzaldehyde. According to the embodiment of the application, the method comprises the step of carrying out formylation reaction on carbon monoxide and alkylbenzene under catalysis of a hexafluorophosphoric acid solution to obtain the para-alkylbenzene formaldehyde, wherein the hexafluorophosphoric acid solution contains hexafluorophosphoric acid and hydrogen fluoride. The complex formed by hexafluorophosphoric acid and alkylbenzene is used for catalyzing formylation reaction, so that disproportionation reaction caused by contact of alkylbenzene and Lewis acid (PF 5 or BF 3 and the like) is avoided. Therefore, the method can effectively inhibit the occurrence of disproportionation reaction, simplify the post-treatment process and improve the yield and purity of the paraalkylbenzaldehyde. According to an embodiment of the present application, the method may further comprise at least one of the following additional technical features: According to an embodiment of the application, the hexafluorophosphoric acid is obtained by a first reaction of Hydrogen Fluoride (HF) with phosphorus pentafluoride (PF 5) to give the hexafluorophosphoric acid (HPF 6). Since alkylbenzene is easily subjected to disproportionation reaction under the action of Lewis acid (BF 3 or PF 5, etc.), boron trifluoride and hydrogen fluoride cannot form stable tetrafluoroboric acid, while phosphorus pentafluoride and hydrogen fluoride can form stable hexafluorophosphoric acid under certain conditions, thereby avoiding contact of alkylbenzene and Lewis acid. Thus, by using phosphorus pentafluoride instead of boron trifluoride, the occurrence of disproportionation reaction is successfully reduced. The substitution not only optimizes the reaction process and simplifies the post-treatment process, but also improves the yield and purity of the p-alkyl benzaldehyde. According to an embodiment of the present application, the molar ratio of the hydrogen fluoride to the phosphorus pentafluoride is not lower than 5:1. Thus, by making the molar ratio of hydrogen fluoride to phosphorus pentafluoride within the above-mentioned range, it is possible to ensure complete conversion of phosphorus pentafluoride into hexafluorophosphoric acid, avoiding contact of alkylbenzene and lewis acid, and thus avoiding occurrence of alkylbenzene disproportionation reaction. According to the embodiment of the application, the temperature of the first reaction is-30 ℃ to 0 ℃. By making the first reaction temperature within the above range, it is possible to ensure complete conversion of phosphorus pentafluoride into hexafluorophosphoric acid without risk of pressure runaway (pressure 5MPa or less) due to severe heat release. According to an embodiment of the application, the formylation reaction is carried out in the same vessel as the first reaction. The formylation reaction and the first reaction are carried out in the same container, so that the process can be simplified, and the hexafluorophosphoric acid is prevented from being decomposed into hydrogen fluoride and phosphorus pentafluoride in the material transferring process. The method is favorable for forming a stable complex by utilizing the generated hexafluorophosphoric acid and the raw material alkylbenzene in time in the reaction process, thereby improving the yield of the product and the reaction efficiency. According to an embodiment of the present application, the molar ratio of the alkylbenzene to the phosphorus pentafluoride is (0.5-1.5): 1. By the addition ratio in the above range, a stable complex between alkylbenzen