4-Hydroxyphenylacetic acid can be obtained through the following synthetic routes:
1. Styrene oxidation method:
Styrene can be oxidized to produce 4-hydroxyphenylacetic acid. Styrene is reacted with hydrogen peroxide at high temperature to produce 4-hydroxyphenylacetic acid. Specific steps are as follows:
(1) Put styrene (1.0 mol), benzoyl peroxide (0.05 mol) and catalyst (such as ammonium vanadate, sodium vanadate, etc.) into the reaction kettle.
(2) Add an appropriate amount of oxygen into the reaction kettle, then raise the reaction temperature to 80-90°C, and react for 2-3 hours.
(3) After the reaction, cool the reaction solution to room temperature, add an appropriate amount of water and adjust the pH to around neutral, so that 4-hydroxyphenylacetic acid can be fully precipitated in water.
(4) After filtering the precipitate, washing with water and drying to obtain 4-hydroxyphenylacetic acid product with higher purity.
2. Phthalate decarboxylation method:
Phthalic acid undergoes decarboxylation to produce 4-hydroxyphenylacetic acid.
(1) Put 4-hydroxyphenylacetic acid (1.0 mol) and phthalic acid (1.1 mol) into the reaction kettle.
(2) Add an appropriate amount of catalyst (such as molybdenum trioxide, hydrogen peroxide, etc.) and an appropriate amount of solvent (such as water, ethanol, etc.) into the reaction kettle.
(3) Raise the reaction temperature to 120-140°C, react for 6-8 hours, and keep stirring during the reaction.
(4) After the reaction, cool the reaction solution to room temperature, and add an appropriate amount of acid or alkali to adjust the pH value, so that 4-hydroxyphenylacetic acid is fully precipitated in water.
(5) After filtering the precipitate, washing with water and drying to obtain 4-hydroxyphenylacetic acid product with high purity.
It should be noted that the synthesis of 4-hydroxyphenylacetic acid by decarboxylation of phthalic acid requires the selection of appropriate catalysts and solvents, as well as reaction temperature and time, and these factors will affect the effect of the reaction and the purity of the product. In addition, continuous stirring is required during the reaction to ensure that the reaction proceeds uniformly.
3. Methyl phthalate reduction method:
Methyl phthalate undergoes a catalytic hydrogenation reduction reaction to generate 4-hydroxyphenylacetic acid, and the specific steps are as follows.
(1) Take methyl phthalate (1.2 mol) and hydrogen (6-8 atm) into the reaction kettle.
(2) Add a suitable catalyst (such as palladium carbon, platinum carbon, etc.) and an appropriate amount of solvent (such as ethanol, methanol, etc.) into the reactor.
(3) Raise the reaction temperature to 50-80°C, and react for 8-10 hours. Stirring is required during the reaction.
(4) After the reaction, cool the reaction solution to room temperature, and add an appropriate amount of acid or alkali to adjust the pH value, so that 4-hydroxyphenylacetic acid is fully precipitated in water.
(5) After filtering the precipitate, washing with water and drying to obtain 4-hydroxyphenylacetic acid product with high purity.
4. Styrene hydroxylation method:
Styrene can be hydroxylated in the presence of potassium permanganate to produce 4-hydroxyphenylacetic acid. Specific steps are as follows:
(1) Take styrene (1.0 mol), hydrogen peroxide (30% H2O2) and catalyst (such as ammonium vanadate, etc.) into the reaction kettle.
(2) Add an appropriate amount of solvent (such as ethanol, water, etc.) into the reaction kettle.
(3) Raise the reaction temperature to 60-80°C, react for 6-8 hours, and keep stirring during the reaction.
(3) After the reaction, cool the reaction solution to room temperature, and add an appropriate amount of acid or alkali to adjust the pH value, so that 4-hydroxyphenylacetic acid can be fully precipitated in water.
(4) After filtering the precipitate, washing with water and drying to obtain 4-hydroxyphenylacetic acid product with higher purity.
5. Hydroxylation of acetophenone:
Acetophenone can be hydroxylated in the presence of hydrogen peroxide to produce 4-hydroxyphenylacetic acid.
(1) Take acetophenone (1.0 mol), hydrogen peroxide (30% H2O2) and catalyst (such as ammonium vanadate, etc.) into the reaction kettle.
(2) Add an appropriate amount of solvent (such as ethanol, water, etc.) into the reaction kettle.
(3) Raise the reaction temperature to 60-80°C, react for 6-8 hours, and keep stirring during the reaction.
(4) After the reaction, cool the reaction solution to room temperature, and add an appropriate amount of acid or alkali to adjust the pH value, so that 4-hydroxyphenylacetic acid is fully precipitated in water.
(5) After filtering the precipitate, washing with water and drying to obtain 4-hydroxyphenylacetic acid product with high purity.
It should be noted that the synthesis of 4-hydroxyphenylacetic acid by the hydroxylation of acetophenone requires selection of an appropriate catalyst and solvent, as well as reaction temperature and time, and these factors will affect the effect of the reaction and the purity of the product. In addition, continuous stirring is required during the reaction to ensure that the reaction proceeds uniformly. At the same time, pay attention to the safety of operation to avoid accidents caused by hydrogen peroxide leakage.
4-Hydroxyphenylacetic acid, also known as p-hydroxyphenylacetic acid, is an important organic compound. It has many important chemical properties and can be used to prepare different compounds. Here are some details about the reactive properties of 4-hydroxyphenylacetic acid.
First of all, the hydroxyl group in 4-hydroxyphenylacetic acid has strong electrophilicity and basicity, and can react with acids and acylating agents to form corresponding esters and acylated products. For example, it can react with alcohols to generate corresponding esterification products for the preparation of aromatic esters. In addition, 4-hydroxyphenylacetic acid can also react with acid anhydride to form the corresponding acylated product.
Secondly, the carboxyl group in 4-hydroxyphenylacetic acid also has strong reactivity, and can undergo esterification and amidation reactions with alcohols and amines to form corresponding esters, amides and other products. For example, it can react with ethanol to generate corresponding ester products for the preparation of aromatic acid esters.
In addition, 4-hydroxyphenylacetic acid can also be reduced to phenols or oxidized to aldehydes, ketones, etc. through redox reactions. For example, it can be reduced to p-hydroxybenzaldehyde by reduction reaction for the preparation of related compounds.
Finally, 4-hydroxyphenylacetic acid can undergo condensation reactions with other compounds under appropriate conditions to form a variety of different condensation products. For example, it can undergo an acid-catalyzed condensation reaction with styrene to form products such as 3-styryl-4-hydroxyphenylacetic acid.