Hydroxybenzoic acid (PHBA) is an important organic chemical raw material, widely used in fields such as medicine, pesticides, dyes, spices, etc. The following will provide a detailed introduction to the manufacturing method of hydroxybenzoic acid
1、 The phenol method is the main production method of p-hydroxybenzoic acid, and its process route is as follows:
1 Phenol reacts with potassium hydroxide to form phenol potassium salt
2. Phenol potassium salt reacts with carbon dioxide to produce potassium p-hydroxybenzoate
3. Potassium p-hydroxybenzoate is obtained by acidification, crystallization, drying, and other steps to obtain p-hydroxybenzoic acid
The advantages of this method are easy availability of raw materials, simple operation, and high product purity. However, the production process of this method will generate a large amount of wastewater and exhaust gas, causing certain pollution to the environment
2、 Biological method is a method of producing p-hydroxybenzoic acid through microbial fermentation. The process route is as follows:
1 Inoculate phenol as a carbon source and energy source with p-hydroxybenzoic acid producing bacteria
2. By controlling fermentation conditions, microorganisms metabolize to produce p-hydroxybenzoic acid
3. By using separation and purification technology, high-purity para hydroxybenzoic acid is obtained
The advantage of biological method is that the production process is relatively environmentally friendly and does not produce a large amount of wastewater and exhaust gas. However, this method has a longer production cycle, lower production efficiency, and higher cost
3、 Other methods: In addition to the above two methods, there are also some other methods for producing p-hydroxybenzoic acid, such as:
1 Benzoic acid method: Benzoic acid reacts with potassium hydroxide to produce potassium benzoate, which is then carboxylated with carbon dioxide to produce potassium p-hydroxybenzoate. After acidification, crystallization, drying, and other steps, p-hydroxybenzoic acid is obtained
2. Benzaldehyde method: Benzaldehyde reacts with potassium hydroxide to produce potassium benzylate, which is then carboxylated with carbon dioxide to produce potassium p-hydroxybenzaldehyde. After reduction, acidification, crystallization, drying, and other steps, p-hydroxybenzoic acid is obtained
The advantage of these methods is that they can reduce production costs to a certain extent, but the operation process is more cumbersome, and the product purity may not be as good as phenol method and biological method
In summary, there are various manufacturing methods for p-hydroxybenzoic acid, and the advantages, disadvantages, and applicability of each method are different. When selecting production methods, it is necessary to comprehensively consider the specific situation to ensure the economic, environmental, and sustainable nature of the production process.
