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CN-122010653-A - Method for brominating deactivated aromatic compound

CN122010653ACN 122010653 ACN122010653 ACN 122010653ACN-122010653-A

Abstract

The invention relates to the technical field of organic synthesis, in particular to a bromination method of a passivated aromatic compound. The bromination method comprises the step of contacting passivated aromatic compound, bromine and sodium periodate in an acidic system containing sulfuric acid and liquid organic acid for bromination to obtain aromatic bromide. The bromination method has the advantages of low cost, simple synthesis, mild reaction conditions, higher product yield and purity, higher applicability and safety.

Inventors

  • WANG JU
  • CHU BOZHAO
  • ZHONG SIQING
  • LIU HAOXIN

Assignees

  • 中国石油化工股份有限公司
  • 中石化（上海）石油化工研究院有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. A process for brominating a passivated aromatic compound comprising the steps of: in an acid system containing sulfuric acid and liquid organic acid, contacting a passivated aromatic compound shown in a formula (I), bromine and sodium periodate to carry out bromination to obtain an aromatic bromide shown in a formula (II);
  2. 2. a process according to claim 1, wherein the molar ratio of passivating aromatic compound of formula (I), bromine and sodium periodate is from 1:0.5 to 1:0.25 to 1, preferably from 1:0.5 to 1:0.3 to 1, more preferably from 1:0.5 to 0.7.
  3. 3. The method according to claim 1 or 2, wherein, The molar ratio of the deactivated aromatic compound of formula (I), the liquid organic acid and water is 1:7 to 11:22 to 34, preferably 1:8.5 to 10.5:27.5 to 33.3, and/or The liquid organic acid is one or more of acetic acid, formic acid, propionic acid and lactic acid; Preferably, the organic acid is a mixture of formic acid and lactic acid, and the molar ratio of the formic acid to the lactic acid is 1:0.2-0.6 based on the liquid organic acid.
  4. 4. A process according to any one of claims 1 to 3, wherein the molar ratio of passivating aromatic compound of formula (I) to sulfuric acid, calculated as H 2 SO 4 , is from 1:0.01 to 15, preferably from 1:1.9 to 11.3, more preferably from 1:7 to 10.
  5. 5. The method of any one of claims 1-4, wherein R 1 、R 2 in the passivated aromatic compound of formula (I) is each independently selected from one of H and a passivating substituent.
  6. 6. The method of claim 5, wherein the passivating substituent groups are electron withdrawing groups comprising one or more of a strong electron withdrawing group, a medium electron withdrawing group, and a weak electron withdrawing group.
  7. 7. The method of claim 6, wherein, The strong electron withdrawing group is selected from one or more of tertiary amine positive ions, nitro and trihalomethyl, preferably trihalomethyl is-CX 3 , wherein X is F and/or Cl, and/or The electron withdrawing group is selected from one or more of cyano and sulfonic acid groups, and/or The weak electron withdrawing group is selected from one or more of F atom, cl atom, acyl group and carboxyl group.
  8. 8. The method according to any one of claims 1 to 7, wherein H is the position of benzene ring 1, and R1 is the position of benzene ring 2, or 3, or 4, or 5, or 6.
  9. 9. The method according to any one of claims 1 to 8, wherein H is the position of benzene ring 1, and R2 is the position of benzene ring 2, or 3, or 4, or 5, or 6.
  10. 10. The method according to any one of claims 1-9, wherein, The passivated aromatic compound is one or more selected from 2-chlorobenzoic acid, benzoic acid, benzotrifluoride, chlorobenzene, m-nitrobenzaldehyde and benzaldehyde; And/or The conditions of the contacting include: at a temperature of 20-70℃, and/or The time is 1-4 hours; preferably, the method comprises the steps of, At a temperature of 40-70℃, and/or The time is 2-4 hours.

Description

Method for brominating deactivated aromatic compound Technical Field The invention relates to the technical field of organic synthesis, in particular to a bromination method of a passivated aromatic compound. Background Bromine on the aromatic ring is a very mature organic reaction in the organic synthesis process, and has been studied, applied and improved by countless scientists since the discovery of the 19 th century. Aromatic bromo-compounds are important intermediates, which can be used as precursors of organometallic reagents, and can be widely used in the synthesis of pharmaceutical, pesticide intermediates and natural products, and also take important roles in the chemical industries of dyes, semiconductors, liquid crystal materials and the like. Because aromatic bromo-compounds have wide synthetic potential, economic, efficient, highly selective, safe and environment-friendly aromatic ring bromination methods remain an important goal generally pursued in the chemical industry field. The synthesis of aromatic brominated compounds is mainly carried out by an indirect method and a direct method. The indirect method mainly uses Sandmeyer reaction to achieve the purpose of denitrification and bromination by aromatic amine through intermediate diazonium salt, or obtains bromoaromatic hydrocarbon through functional group conversion (halogen exchange). The direct process can be divided into four general categories, direct bromination by elemental bromine, bromination by N-bromosuccinimide (NBS), bromination by the adduct of a bromine molecule with a halide, bromination by in situ oxidation to zero-valent bromine, and the like. There are many methods for brominating aromatic compounds, but stringent experimental conditions are required to brominate the deactivated aromatic compounds. Bromination reactions that deactivate aromatic compounds have been of interest. The conditions for deactivating bromine on the aromatic ring of the aromatic compound become quite severe due to the presence of electron withdrawing groups on the aromatic ring, and side reactions are also increased. For example, if the trifluoromethyl benzene is directly brominated, 15% -30% of the trifluoromethyl benzene is changed into m-bromobenzoic acid, and the direct bromination of acetophenone needs to be performed after the direct bromination of acetophenone is reacted with excessive aluminum trichloride, so that the operation is very complicated. Bromine is adopted as a brominating agent to directly bromize and passivate aromatic compounds, a great deal of concentrated sulfuric acid or one of Br2/BrF3,Br2/AgNO3/H2SO4,Br2/HgO/H2SO4,Br2/Hg2O,HF,SbF5/Br2 and a mixture of benzoyl peroxide and lithium bromide is often required to be added for bromination reaction, the reaction condition is harsh, and a metal catalyst and the like are often required to be used. Rajesh et al, however, report that by brominating the passivated aromatic compound in concentrated H 2SO4 using NBS, the reaction proceeds at 60℃with good yields. NBS has long been used for the bromination of deactivated aromatics (e.g., NBS/TFA/H 2SO4,NBS/BF3-H2O,NBS/H2SO4 aqueous solutions, etc.), but its industrial applicability is limited due to the high cost of the NBS preparation process. However, kumar et al report that adding NaBr and NaIO 4 to a concentrated sulfuric acid system bromizes and passivates aromatic compounds, while avoiding the use of NBS, the use amount of concentrated sulfuric acid is large, which is not beneficial to the treatment of the three wastes in the later stage, and increases the cost of the three wastes treatment. Therefore, there is a need for a low cost, simple synthesis, mild reaction conditions, high applicability and safe bromination process for deactivating aromatic compounds. Disclosure of Invention The invention aims to solve the problems of high treatment cost, complex process, harsh reaction conditions and lower product yield of raw materials and three wastes in the prior art, and provides a bromination method of a passivated aromatic compound, which has the advantages of low treatment cost, simple synthesis, mild reaction conditions, higher product yield and purity, higher applicability and safety. According to a first aspect of the present invention there is provided a process for the bromination of a passivated aromatic compound comprising the steps of: in an acid system containing sulfuric acid and liquid organic acid, contacting a passivated aromatic compound shown in a formula (I), bromine and sodium periodate to carry out bromination to obtain an aromatic bromide shown in a formula (II); The bromination method of the passivated aromatic compound has the advantages of low cost, simple process, mild reaction conditions, higher product yield and purity, higher applicability and safe operation. The reason is presumed that in the bromination system of the passivated aromatic compound, bromine and sodium periodate of the present invention, th