Optimizing the model reaction conditions for the synthesis of imidazole 4a^a.

Entry	Catalyst (g)	Solvent	Temperature (°C)	Time (min)	Yieldb (%)
1	0.005	EtOH	80	90	70
2	0.010	EtOH	80	60	82
3	0.020	EtOH	80	45	98
4	0.030	EtOH	80	45	95
5	0.040	EtOH	80	45	93
6	0.020	MeOH	65	60	90
7	0.020	DMSO	120	60	85
8	0.020	CH3CN	80	60	55
9	0.020	H2O	100	90	20
10	0.020	EtOH : H2O (1 : 1)	100	90	35
11	0.020	CH2Cl2	40	90	58
12	0.020	EtOH	50	90	60
13	0.020	EtOH	60	60	75
14	0.020	EtOH	70	45	92
15	Zeolite-NaY (0.02)	EtOH	80	120	15
16	SO3H@zeolite-Y (0.02)	EtOH	80	55	90
17	—	EtOH	80	240	50

^aReaction conditions: benzil (1 mmol), benzaldehyde (1 mmol), ammonium acetate (2 mmol) and catalyst in solvent.

^bIsolated yield.