Manufacturing Methods of Benzaldehyde
Benzaldehyde is an important organic chemical raw material, widely used in the fields of medicine, pesticides, spices, plastics and dyes. In this article, we will introduce the manufacturing methods of benzaldehyde, including chemical synthesis method and biological method.
I. Chemical synthesis method
1. Benzyl alcohol oxidation method
Benzyl alcohol oxidation method is one of the commonly used methods to manufacture benzaldehyde. This method takes benzyl alcohol as raw material and produces benzaldehyde through oxidation reaction. Commonly used oxidizing agents include potassium permanganate, potassium dichromate, hydrogen peroxide and so on. Among them, acidic potassium permanganate oxidation method is more commonly used, the reaction formula is as follows:
Reaction conditions: acidic conditions, temperature control at 60-80 ℃, reaction time of about 2-3 hours.
Advantages: easy to obtain raw materials, simple operation, low cost.
Disadvantages: generating a large amount of waste water, polluting the environment, and the yield is not high.
2. Methyl benzoate reduction method
Methyl benzoate reduction method is to use methyl benzoate as raw material to produce benzaldehyde by reduction reaction. Commonly used reducing agents include lithium aluminum hydrogen, sodium borohydride and so on. The reaction formula is as follows:
Reaction conditions: under the protection of inert gas, heating to 80-120 ℃, reaction time about 2-4 hours.
Advantages: higher yield, better product quality.
Disadvantages: higher cost of raw materials, more complex operation.
II. Biological method
Biological method is the method of converting benzyl alcohol or benzoic acid into benzaldehyde through the action of microorganisms or enzymes. Compared with the chemical synthesis method, the biological method has the advantages of environmental protection, energy saving and high efficiency, and it has gradually become a hot spot of research.
1. Microbial oxidation
Microbial oxidation is a method of oxidizing benzyl alcohol to benzaldehyde using certain microorganisms. Commonly used microorganisms include Pseudomonas aeruginosa and Bacillus alkali-producing bacteria. The reaction conditions of this method are mild, but it requires a long cultivation and acclimatization process, and the species and activity of the microorganisms have a large influence on the reaction.
2. Enzyme-catalyzed method
Enzyme-catalyzed method is a method that uses specific enzymes to catalyze the conversion of benzyl alcohol or benzoic acid to benzaldehyde. Commonly used enzymes include alcohol dehydrogenase and aldehyde dehydrogenase. The method is highly stereoselective and regioselective and can obtain high purity benzaldehyde. However, the source and stability of the enzyme are the key factors restricting the application of the method.
In summary, there are various methods for manufacturing benzaldehyde, including chemical synthesis and biological methods. Different methods have different advantages, disadvantages and scope of application, and the suitable method should be selected according to the specific production needs and conditions. Meanwhile, with the increasing awareness of environmental protection and the continuous development of biotechnology, the application of biological method in the manufacture of benzaldehyde will have a broader prospect.
