Method for preparing pentafluorophenol

A technology of pentafluorophenol and pentafluorobromobenzene, which is applied in the field of preparation of TFT liquid crystals and pharmaceutical intermediates pentafluorophenol, can solve the problems of hydrolysis of pentafluorobenzene boric acid into pentafluorobenzene, increased probability of coupling reaction, electronic Low cloud density and other issues, achieve the effect of reduced response time, improved security performance, and good security

Active Publication Date: 2013-12-04
DALIAN QIKAI MEDICAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0010] (a) Due to the molecular structure of pentafluorobromobenzene, all positions except bromine are occupied by fluorine, and fluorine is a strong electron-withdrawing group, which makes the electron cloud density on carbon very low, while the format on aromatics Initiation tends to occur at a location with a high electron cloud density, so initiation of this format is very difficult and requires high temperatures, thereby greatly increasing the probability of coupling reactions
[0011] (b) Since the Grignard reaction is both an initiation process and an exothermic process, when the Grignard reaction is initiated, once the concentration of the raw material in the kettle is too high to initiate successfully, it is easy to cause a sharp reaction, which makes the reaction uncontrollable and causes very serious safety hazards. as a result of
[0012] (c) In step (3), due to the use of the weaker polar organic solvent dichloroethane, the intermediate product pentafluorophenylboronic acid is difficult to dissolve in it, and it is a heterogeneous reaction, so there is a long reaction time and it is easy to cause Pentafluorobenzene boric acid is hydrolyzed into pentafluorobenzene, resulting in low yield and other disadvantages

Method used

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  • Method for preparing pentafluorophenol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Step (1): Dry the 1000ml four-necked bottle, replace it with nitrogen, start stirring to maintain good nitrogen protection, add 365ml THF, 200g (0.81mol) pentafluorobromobenzene 415ml (0.83mol) of isopropylmagnesium chloride / THF solution was added dropwise at ℃, and then kept at 40-50℃ for 2 hours.

[0037] Step (2): Add 500ml THF and 97g (0.94mol) trimethyl borate into a 2000ml four-necked bottle, cool down to -10~0°C, add the Grignard reagent prepared in the above step (1) dropwise, and then heat After reaching room temperature and keeping it warm for 2 hours, after acidifying with hydrochloric acid, washing and separating the layers, the organic layer was distilled under reduced pressure, and the residue was crystallized and filtered to obtain 126 g of pentafluorophenylboronic acid solid, with a yield of 74%.

[0038] Step (3): Add 450ml of glacial acetic acid into a 1000ml four-necked bottle, start stirring, add 124g of the above-mentioned pentafluorophenylboronic a...

Embodiment 2

[0042] Step (1): Dry the 1000ml four-necked bottle, replace it with nitrogen, start stirring to maintain good nitrogen protection, add 365ml THF, 200g (0.81mol) pentafluorobromobenzene 470ml (0.94mol) of isopropylmagnesium chloride / THF solution was added dropwise at ℃, and then kept at 40-50℃ for 2 hours.

[0043] Step (2): Add 500ml THF and 113g (1.09mol) trimethyl borate into a 2000ml four-neck bottle, cool down to -10~0°C, add the Grignard reagent prepared in the above step (1) dropwise, and then heat After reaching room temperature and keeping warm for 2 hours, then acidified with hydrochloric acid, washed and separated, the organic layer was distilled under reduced pressure, and the residue was crystallized and filtered to obtain 129 g of pentafluorophenylboronic acid solid, with a yield of 75%.

[0044] Step (3): Add 400ml of glacial acetic acid into a 1000ml four-neck bottle, start stirring, add 124g of the above-mentioned pentafluorophenylboronic acid solid, add 81g (0...

Embodiment 3

[0046] Step (1): Same as Example 2.

[0047]Step (2): Add 500ml THF and 129.6g (1.25mol) trimethyl borate into a 2000ml four-necked bottle, cool down to -20~-10℃, add the Grignard reagent prepared in the above step (1) dropwise, Then heated to room temperature and kept warm for 2 hours, then acidified with hydrochloric acid, washed and separated, the organic layer was distilled under reduced pressure, and the residue was crystallized and filtered to obtain 120 g of pentafluorophenylboronic acid solid, with a yield of 70%.

[0048] Step (3): Add 300ml of glacial acetic acid into a 1000ml four-necked bottle, start stirring, add 120g of the above-mentioned pentafluorophenylboronic acid solid, add 75g (0.66mol) of hydrogen peroxide dropwise into the bottle at 25-35°C, and the dropwise addition is completed Insulate for 2 hours, then add sodium bisulfite solution into the bottle to destroy excess hydrogen peroxide, and obtain 95 g of white crystals with a main content of ≥99.5% thr...

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Abstract

The invention provides a method for preparing pentafluorophenol. The method is characterized by comprising the following steps of 1, dropping alkyl magnesium halide into pentafluorophenol organic solvent to carry out format exchange at 30 DEG C to 60 DEG C, 2, dropping the grignard reagent obtained in the step 1 to borate B (OR) 3 organic solvent of -20 DEG C to 30 DEG C to carry out esterification reaction, and then acidifying and distilling to recycle the organic solvent to obtain penta fluoro benzeneboronic acid, and 3, reacting the penta fluoro benzeneboronic acid obtained in the step 2 with the organic solvent and peroxide at 10 DEG C to 50 DEG C to generate the pentafluorophenol and finally rectifying the pentafluorophenol to obtain accepted products. The raw materials of the method are easy to obtain. The method is stable in process, convenient to operate, high in purity (larger than or equal to 99%) of products, high in yield (more than 65%), low in cost, good in safety and suitable for industrial large-scale production.

Description

technical field [0001] The invention belongs to the field of chemical industry, and in particular relates to a preparation method of TFT liquid crystal and pharmaceutical intermediate pentafluorophenol. Background technique [0002] Pentafluorophenol (2,3,4,5,6-Pentafluorophenol) is a polyfluorinated liquid crystal compound with small steric hindrance, suitable for the preparation of single crystal compounds, and is an important intermediate for the preparation of high-performance liquid crystal materials. Important intermediates for performance drugs. [0003] Regarding the preparation method of pentafluorophenol, Patent Document 1 (CN1847210A) discloses a method of using pentafluorobromobenzene as a starting material and sequentially adopting the following steps to synthesize pentafluorophenol: [0004] (1) Grignard reagent is obtained by performing Grignard reaction on pentafluorobromobenzene; [0005] (2) Add the above Grignard reagent dropwise to B(OR) at -24-12°C 3 ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C37/01C07C39/27
Inventor 姜殿平陈昌盛李成斌
Owner DALIAN QIKAI MEDICAL TECH
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