Effect of solvent on the synthesis of 5-phenyl 1H-tetrazole^a.

Entry	Solvent	Yieldc (%)
1b	CH3CN	43
2	DMF	81
3	DMSO	64
4b	EtOH	31
5	Toluene	0
6	H2O	92
7	Solvent-free	0

^aReaction condition: benzaldehyde (1 mmol), hydroxylamine hydrochloride (1.2 mmol), sodium azide (1.5 mmol), solvent (2 mL), humic acid (0.1 g) at 100 °C for 4 h.

^bReaction was performed under reflux condition.

^cIsolated yield.