Table 2.

Yield dependence of pyridine-2-ammonium sulfate (8)^a and 2,5-dihydroxypyridine (11)^b on the amount and type of catalyst.

Amount of catalyst, wt %	Yield of 8/11, %
	PcСо	PcFe(II)	PcFe(III)	PcMn	PcNi	PcZn
0	19/19
0.01	55/43	36/39	37/37	23/30	26/38	21/23
0.05	67/60	45/54	48/51	45/45	38/47	33/35
0.1	78/71	55/62	57/60	45/49	49/53	42/47
0.15	–/72	–/64	–/62	–/52	–/55	–/49
0.2	81/71	57/63	60/60	50/50	51/53	47/49
0.3	81/–	57/–	58/–	48/–	52/–	46/–

^aMole ratio Py/NaOH/APS 1:4:1.5, 45 °C; 10 h; ^bmole ratio HPy/NaOH/APS 1:4:2; 45 °C; 8 h.