Table 1. Catalyst Optimization Studies for the Formation of Aniline 2a^a.

entry	catalyst (mol %)	time	yield 2a(%)b
1	ZnO (2.5 mol %)	12 h	c
2	Zn0.7Mn0.3O2−δ (2.5 mol %)	12 h	c
3	Zn0.7Fe0.3O2−δ (2.5 mol %)	12 h	c
4	NiFe2O4 (2.5 mol %)	12 h	c
5	CuFe2O4 (2.5 mol %)	12 h	c
6	SnO2 (2.5 mol %)	12 h	c
7	TiO2 (2.5 mol %)	12 h	c
8d	Pd/C (2.5 mol %)	1 h	46
9	Pd/TiO2 (0.1 mol %)	15 min	82
10	Au/TiO2 (0.1 mol %)	10 min	80
11	Pd–Au/TiO2 (0.1 mol %)	5 min	96

^aReaction conditions: nitrobenzene (1 mmol), hydrazine monohydrate (0.5 mL), and catalyst.

^bIsolated yields of product 2a.

^cStarting material 1a recovered.

^dPd/C (palladium on activated charcoal).