Manufacturing method of o-nitrochlorinated benzene
I. Introduction
o-nitrochlorinated benzene is an important organic chemical raw material, which is widely used in dyestuffs, pharmaceuticals, pesticides and other fields. Therefore, it is of great practical significance to study the manufacturing method of o-nitrochlorobenzene. In this paper, we will introduce the method of preparing o-nitrochlorobenzene by nitration reaction and chlorination reaction with benzene, chlorine and nitric acid as raw materials.
II.Experimental Principle
The preparation reaction of o-nitrochlorobenzene mainly includes two steps of nitration reaction and chlorination reaction. Firstly, benzene reacts with mixed acids (nitric acid and sulfuric acid) to produce nitrobenzene, and then nitrobenzene reacts with chlorine to produce o-nitrochlorobenzene.
III. Experimental Steps
1. Nitration Reaction
In a 250mL three-necked flask equipped with a stirrer, thermometer, and dropping funnel, add 60mL of benzene and 60mL of mixed acid (nitric acid and sulfuric acid in the ratio of 1:1 by volume), and heat it up to 60°C to begin the dropwise addition of mixed acid. After the dropwise addition was completed, the reaction was continued to be heated for 2 hours. At the end of the reaction, the reaction solution was poured into ice water, a yellow solid was precipitated, filtered, and washed to neutrality with cold water to obtain nitrobenzene.
2. Chlorination reaction
In a 250 mL three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel, nitrobenzene and 60 mL of chloroform prepared above were added and heated to 40°C. The reaction was continued for 2 hours. Then, 30 mL of chlorine gas was slowly added dropwise through a constant pressure dropping funnel to control the reaction temperature between 40-50°C. After the dropwise addition, the reaction was continued to be stirred for 1 hour. At the end of the reaction, the reaction solution was poured into ice water, and a yellow-green solid was precipitated, pumped and filtered, and washed to neutrality with cold water to obtain the crude product o-nitrochlorobenzene.
IV. Experimental results and discussion
1. Experimental results
Through the above experimental steps, we successfully prepared o-nitrochlorobenzene with high yield and purity of more than 90%.
2. Experimental Discussion
In the nitration reaction, the selection and dosage of nitrating agent have great influence on the experimental results. In this experiment, mixed acid was used as the nitrifying agent, and the ratio of nitric acid and sulfuric acid was 1:1. Under this condition, the nitrification reaction was carried out more completely, and the purity of nitrobenzene obtained was higher. In the chlorination reaction, controlling the reaction temperature is the key, too high temperature will lead to the increase of side reactions and affect the purity of the product. In this experiment, controlling the reaction temperature between 40-50℃ can effectively reduce the occurrence of side reactions and improve the purity of the product.
V. Conclusion
In this paper, o-nitrochlorobenzene was prepared by nitration reaction and chlorination reaction using benzene, chlorine and nitric acid as raw materials. The experimental results show that the method is easy to operate, the yield is high and the purity reaches more than 90%. The purity and yield of the product can be further improved by controlling the reaction conditions and optimizing the experimental operation.
