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

Entry	Catalyst loading (g)	Yieldb (%)
1	None	0
2	0.04	48
3	0.07	76
4	0.10	92
5	0.13	92
6	0.16	93

^aReaction condition: benzaldehyde (1 mmol), hydroxylamine hydrochloride (1.2 mmol), sodium azide (1.5 mmol), H₂O (2 mL), catalyst humic acid at 100 °C for 4 h.

^bIsolated yield.