1. Add a small amount of zinc powder to prevent aniline from oxidizing during the reaction;

2. Use an excess amount of ice HAc and evaporate the generated water at any time to allow the aniline to react completely ;

3. The reaction time is at least 30 minutes. Otherwise, the reaction may be incomplete and affect the yield;

4. The fractionation temperature should not be too high during the reaction to avoid a large amount of acetic acid evaporating and reducing the yield. rate;

5. During recrystallization, hot filtration is a key step. The Buchner funnel and suction filter bottle must be preheated. The size of the filter paper must be appropriate, and the suction filtration process must be fast to avoid the product in the Buchner funnel. Medium crystallization;

6. During the recrystallization process, the crystals may not precipitate. You can use a glass rod to rub the wall of the beaker or add crystal seeds to make the crystals precipitate.