The synthesis of 2,3-diphenylquinoxaline proceeds as follows:

the following procedure is performed:

1. Why after the ultrasound bath is the reaction mixture taken to an ice bath? for what purpose?.

2. indicate what by-products, reagents, etc. are eliminated in the filtration.

3. indicate what by-products, reagents, etc. are removed in recrystallization with ethanol.

NH2 p-TSA + H20 Etanol NH2 N.