Optimization experiments for reduction of nitrobenzene to aniline with N₂H₄·H₂O/rGO@Fe₃O₄/ZrCp₂Cl_{x (x = 0, 1, 2)} system^a.

Entry	Catalyst	Amount (mg)	N2H4·H2O (mmol)	Condition	Time (min)	Yield (%)
1	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	20	2	EtOH, r.t.	60	55
2	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	10	2	EtOH, reflux	60	60
3	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	20	2	EtOH, reflux	10	100
4	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	30	2	EtOH, reflux	10	70
5	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	20	1	EtOH, reflux	10	60
6	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	20	2	H2O, 70 °C	60	60
7	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	20	2	H2O–EtOH (1 : 1), 70 °C	60	50
8	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	20	2	EtOAc, reflux	60	20
9	rGO@Fe3O4/ZrCp2Clx (x = 0, 1, 2)	20	2	CH3CN, reflux	60	30
10	rGO@Fe3O4	20	2	EtOH, reflux	60	8
11	ZrCp2Cl2	20	2	EtOH, reflux	60	20
12	ZrCp2Cl2	20	2	H2O, reflux	60	10
13	—	—	2	EtOH, reflux	120	Trace

^aAll reactions were carried out with 1 mmol of nitrobenzene in 2 mL solvent.