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Method for synthesizing 6-hydroxy-2-naphthoic acid

A synthetic method, naphthoic acid technology, applied in chemical instruments and methods, preparation of organic compounds, carboxylate preparation, etc., can solve the problems of rare raw materials, large investment in equipment, and only 37% reaction yield

Inactive Publication Date: 2006-10-11
CHENGDU ORGANIC CHEM CO LTD CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

And in methods 1 and 2, every molecule of 2,6-acid will be generated with a molecule of β-naphthol, which leads to low conversion rate of β-naphthol and also brings separation difficulties to post-treatment
For method 3, it is more dangerous to use carbon monoxide gas in the reaction, and the reaction is at 70kg / cm 2 It is carried out under high pressure, which has high requirements on the reaction equipment, the equipment investment is large, and the preparation of the catalyst is also relatively complicated, and the yield of the reaction is only 37%.
For method 4, the yield of the reaction is quantitative and the conditions of the reaction are relatively mild, but the raw materials for the reaction are rare and the preparation is troublesome.

Method used

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  • Method for synthesizing 6-hydroxy-2-naphthoic acid
  • Method for synthesizing 6-hydroxy-2-naphthoic acid
  • Method for synthesizing 6-hydroxy-2-naphthoic acid

Examples

Experimental program
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Effect test

Embodiment 1

[0023] Add 48.1g of sodium hydroxide (1.2mol) and 250mL of water into a 500mL three-necked flask, stir evenly under ice bath cooling, slowly add 15mL of bromine (0.6mol) dropwise to control the reaction temperature below 5°C, control the low temperature to continue Stir for 20min. Add 80mL dioxane, 27.0g sodium hydroxide (0.67mol), 20.1gI to the prepared sodium hypobromite solution. The temperature was raised to 75°C, and the reaction was refluxed for 2 hours. Stop the reaction, lower the temperature to below 10°C, and continue stirring for 30 minutes. Filter, add 100% water to the obtained solid, and add concentrated hydrochloric acid to adjust the pH to 3-4 while stirring. Heat to reflux, stir for more than 1 hour, cool to below 10°C, and maintain for about 0.5 hours. After filtration, the filter cake was washed with 100 g of water and dried to obtain 20 g of a colorless solid. The resulting solid was crystallized from ethanol 70 g / DMF 10 g. 2-Methoxy-6-naphthoic acid w...

Embodiment 2

[0027] Add 20.0g sodium hydroxide (1.2mol) and 200mL water to a 500mL three-necked flask, stir evenly under ice bath cooling, slowly add 12mL bromine (0.48mol) dropwise to control the reaction temperature below 5°C, control the low temperature to continue Stir for 20min. Add 80mL dioxane, 27.0g sodium hydroxide (0.67mol), and 20.1g I to the prepared sodium hypobromite solution. The temperature was raised to 75°C, and the reaction was refluxed for 2 hours. Stop the reaction, lower the temperature to below 10°C, and continue stirring for 30 minutes. Filter, add 100 mL of water to the obtained solid, and add concentrated hydrochloric acid to adjust the pH to 3-4 while stirring. Heat to reflux, stir for more than 1 hour, cool to below 10°C, and maintain for about 0.5 hours. After filtration, the filter cake was washed with 100 mL of water and dried to obtain 20 g of a colorless solid. The resulting solid was crystallized from ethanol 70 g / DMF 10 g. 2-Methoxy-6-naphthoic acid ...

Embodiment 3

[0029] Add 48.1g of sodium hydroxide (1.2mol) and 250mL of water into a 500mL three-necked flask, stir evenly under ice bath cooling, slowly add 15mL of bromine (0.6mol) dropwise to control the reaction temperature below 5°C, control the low temperature to continue Stir for 20min. Add 80mL dioxane, 27.0g sodium hydroxide (0.67mol), 20.1gI to the prepared sodium hypobromite solution. The temperature was raised to 50° C., and the reaction was kept for 10 hours. Stop the reaction, lower the temperature to below 10°C, and continue stirring for 30 minutes. Filter, add 100 mL of water to the obtained solid, and add concentrated hydrochloric acid to adjust the pH to 3-4 while stirring. Heat to reflux, stir for more than 1 hour, cool to below 10°C, and maintain for about 0.5 hours. After filtering, the filter cake was washed with 100 mL of water and dried to obtain 19 g of a colorless solid. The resulting solid was recrystallized from ethanol 70 g / DMF 10 g. 2-Methoxy-6-naphthoic ...

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Abstract

The invention provides a process for preparing 6- hydroxyl-2- naphthoic acid, which comprises the steps of: reacting compound of formula (I) with halogens under alkaline condition at 0-100 deg C for 7-12hr to obtain compound of formula (II), then reacting compound of formula (II) with HX in acetic acid solution at 70 deg C to backflow temperature to obtain compound of formula (III). The invention can realize high purity and high yield.

Description

technical field [0001] The invention relates to an innovative synthesis method for preparing 6-hydroxy-2-naphthoic acid by using 6-methoxy-2-naphthyl ethyl ketone as a raw material through haloform reaction, and belongs to the field of fine organic chemical industry. Background technique [0002] 6-hydroxyl-2-naphthoic acid as shown in formula (V) is an important raw material for the production of various aromatic polyesters, especially liquid crystal polymers with excellent processability and flow properties and resins with good elasticity and heat resistance or fiber essential. [0003] As methods for producing 6-hydroxy-2-naphthoic acid, the following four are known: [0004] 1. Koble-Schimmit reaction to prepare 6-hydroxy-2-naphthoic acid. The reaction uses the potassium salt of β-naphthol as a raw material to undergo a 6-position carboxylation reaction with carbon dioxide under high temperature and high pressure to prepare 6-hydroxy-2-naphthoic acid. (U.S Patents Nos...

Claims

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Application Information

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IPC IPC(8): C07C51/093C07C65/11
Inventor 王立新彭焕庆王文杜振军
Owner CHENGDU ORGANIC CHEM CO LTD CHINESE ACAD OF SCI
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