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Preparation method of o-ethoxybenzoic acid

A technology of o-ethoxybenzoic acid and salicylic acid, which is applied in the field of preparation of o-ethoxybenzoic acid, can solve problems such as difficulty in realizing large-scale industrial production, uneasy control of reaction conditions, unfavorable industrial production, etc., and facilitates industrialization The effect of low production, low cost and convenient operation

Active Publication Date: 2014-02-05
苏州诚和医药化学有限公司
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  • Description
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Problems solved by technology

[0002]O-ethoxybenzoic acid is an important intermediate in the synthesis of ED drugs (Viagra). There are many reports on the synthesis of this intermediate at home and abroad. The typical There are the following two methods. One is etherification with o-chlorobenzoic acid. This method has high cost of raw materials, and requires high temperature and high pressure operation, which is difficult and is not conducive to industrial production. The other method is to esterify salicylic acid first and then etherify it. The product is obtained by alkaline hydrolysis, but the synthesis cost of this method is high, the reaction conditions are difficult to control, and it is difficult to realize large-scale industrial production

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  • Preparation method of o-ethoxybenzoic acid

Examples

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Effect test

Embodiment 1

[0012] Add 50g (0.36mol) of salicylic acid and 500ml of acetone into the reaction flask, and add 42.6g (0.76mol) of finely ground potassium hydroxide solid (90%) at a temperature of less than 40°C. After the addition, raise the temperature and keep it under reflux for 3 hours , cooled to 20°C, slowly added 86g (0.79mol) ethyl bromide dropwise, after the addition of ethyl bromide was completed, the temperature was raised to reflux, and the reflux state was maintained for 10 hours. After the heat preservation, the acetone was recovered under reduced pressure. After the acetone recovery was completed, 300ml was added Water, 50 grams of 30% liquid caustic soda (that is, liquid sodium hydroxide) (0.38mol) is heated up to 90°C, and kept at this temperature for 2 hours, and cooled to 30-35°C after the heat preservation, and slowly dripped Add glacial acetic acid, control the reaction liquid to be added dropwise to PH=3~4, at this time a large amount of solids precipitated, further coo...

Embodiment 2

[0014] Add 65g (0.47mol) of salicylic acid and 400ml of acetone into the reaction flask, and add 67.3g (1.08mol) of finely ground potassium hydroxide solid (90%) at a temperature of less than 40°C. After the addition, raise the temperature and keep it under reflux for 3 hours , cooled to 20°C, and slowly added 117.8g (1.08mol) bromoethane dropwise. After the dropwise addition of bromoethane, the temperature was raised to reflux, and the reflux state was maintained for 12 hours. After the heat preservation was completed, acetone was recovered under reduced pressure. After the acetone recovery was completed, add 500ml of water, 62.7 grams of 30% liquid caustic soda (that is, liquid sodium hydroxide) (0.47mol) is heated up to 90°C, and kept at this temperature for 3 hours, and cooled to 30-35°C at the end of the heat preservation, and slowly Add glacial acetic acid dropwise, and control the dropwise addition of the reaction solution to PH=3~4. At this time, a large amount of solid...

Embodiment 3

[0016] Add 100g (0.72mol) of salicylic acid and 900ml of acetone into the reaction flask, and add 112.2g (1.80mol) of finely ground potassium hydroxide solid (90%) at a temperature control of less than 40°C. After adding, raise the temperature and keep it under reflux for 3 hours , cooled to 20°C, slowly added 196g (1.80mol) ethyl bromide dropwise, after the addition of ethyl bromide was completed, the temperature was raised to reflux, and the reflux state was maintained for 15 hours. After the heat preservation, the acetone was recovered under reduced pressure. After the acetone recovery was completed, 600ml was added Water, 96 grams of 30% liquid caustic soda (that is, liquid sodium hydroxide) (0.72mol) is heated up to 90°C, and kept at this temperature for 4 hours, and cooled to 30-35°C after the heat preservation, and slowly dripped Add glacial acetic acid, control the reaction liquid to be added dropwise to PH = 3 ~ 4, at this time, a large amount of solids precipitated, f...

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Abstract

The invention relates to a preparation method of o-ethoxybenzoic acid, which comprises the following steps: adding salicylic acid, acetone and potassium hydroxide into a reaction bulb, dropwisely adding bromoethane while stirring at room temperature, heating under reflux for 9-15 hours, recovering the acetone under reduced pressure, adding water and liquid alkali, heating under reflux for 2-4 hours, cooling to room temperature, regulating the pH value to 3-4 with glacial acetic acid, cooling to 1-15 DEG C, separating by vacuum filtration, washing with water, and carrying out vacuum drying to obtain the o-ethoxybenzoic acid, wherein the salicylic acid:potassium hydroxide:bromoethane:liquid alkali mol ratio is 1:(2.0-2.5):(2.1-2.5):1.4. The method has the advantages of simple technique, low raw material cost, high yield and good quality, and is convenient to operate and convenient for industrial production.

Description

technical field [0001] The invention relates to the technical field of pharmaceutical intermediates, in particular to a preparation method of o-ethoxybenzoic acid. Background technique [0002] O-ethoxybenzoic acid is an important intermediate for the synthesis of ED drugs (Viagra). There are many related reports on the synthesis of this intermediate at home and abroad. The following two types are typical, one is etherified with o-chlorobenzoic acid, The raw material cost of this method is high, and it is difficult to operate under high temperature and high pressure, which is not conducive to industrial production. Another method first esterifies salicylic acid and then undergoes etherification and alkali hydrolysis to obtain the product. This method has high synthesis cost and reaction conditions Difficult to control, difficult to realize large-scale industrial production. Contents of the invention [0003] The purpose of the present invention is to provide a kind of pro...

Claims

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Application Information

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IPC IPC(8): C07C65/21C07C51/02C07C51/09
CPCC07C51/02C07C51/412C07C67/11C07C65/21C07C69/92
Inventor 王利明夏秋景陈洁
Owner 苏州诚和医药化学有限公司
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