Optimization of the reaction conditions for the aerobic oxidation of benzyl alcohol^a.

Entry	Catalysts	TEMPO (mmol)	Ligand	Yieldb (%)
1	—	—	NMI	—
	—	0.25	NMI	1
3	Fe3O4	0.25	NMI	1
4	Fe3O4@Cu2O	0.25	—	1
5	Cuc	0.25	NMI	94
6	Cu2Od	0.25	NMI	90
7	Fe3O4@Cu2O	0.25	NMI	80e/>99
8	Fe3O4@Cu2O	0.25	1-Butyl imidazole	99
9	Fe3O4@Cu2O	0.25	1-tert-Butyl imidazole	96
10	Fe3O4@Cu2O–Cu-5	0.25	NMI	78e/>99
11	Fe3O4@Cu2O–Cu-7	0.25	NMI	68e/>99
12	Fe3O4@Cu2O–Cu-9	0.25	NMI	51e/>99
13	Fe3O4@Cu2O–Cu-12	0.25	NMI	46e/98
14	Fe3O4@Cu	0.25	NMI	60e/91
15	Fe3O4@Cu2Of	0.25	NMI	>99

^aReaction conditions: alcohol (5 mmol), catalyst (15 mg), TEMPO (0.25 mmol), NMI (0.25 mmol), acetonitrile (5 mL), 25 °C, 18 h. For the sample coding, the suffix number x of the codes (entries 10–13) in Fe₃O₄@Cu₂O–Cu-x denotes the reaction time in the catalyst preparation.

^bResults by GC analysis.

^c0.14 mmol.

^d0.07 mmol.

^eYield at 12 h.

^fAt 82 °C for 12 h.