I have synthesized 2-Aminobenzophenone with mentioned procedure below, when I wanted to recrystallize the product with boiling ethanol, there was some black participate which showed explosive manner in boiling ethanol but didn't solved even in boiling ethanol, can you suggest
1- what is that black participate?
2-what is the role of acidic reflux in this procedure?
To 21.0mmol of the corresponding benzoyl chloride, 8.4mmol of p-chloroaniline
were added. Then the mixture was heated to about 180–200 C, 10.08mmol of anhydrous
ZnCl2 were added slowly, and the temperature was gradually increased to
220–230 C. The reaction mixture was maintained at reflux for 3 h. Then it was cooled
to 120 C, and hot water was added to remove the benzoic acid, giving a green-brown
product. The obtained green-brown product was added to a mixture of H2SO4,
CH3COOH, and H2O (5.0:3.5:3.0mL) and refluxed for 40 min. Then, about 20–25mL
of ice-water mixture was added, and the reaction mixture was subsequently extracted
using dichloromethane. The organic phase was washed three times using water and a
solution of 10% ammonium hydroxide to neutralize it. The organic phase was dried
with anhydrous sodium sulfate. Its vacuum evaporation yielded a brown-yellow solid,