The reaction conditions and results for the irradiation of 4-methoxyazobenzene (2a).

En.	WL (nm)	Solvent	Acid (conc.)	t (h)	Ratio: t/c-2a : 3a : 4a
1	365	CH3CN	HCO2H (1.26 M)	5	1 : 0 : 0
2	365	CH3CN	AcOH (1.59 M)	3	1 : 0 : 0
3	365	DMF	None	1	1 : 0 : 0
4	365	DMF	HCl (0.05 M)	1	1 : 0 : 0
5	365	DMF	HCl (0.1 M)	1	49 : 1 : 0
6	365	DMF	HCl (0.3 M)	1	16 : 1 : 0
7	365	DMF	HCl (0.5 M)	1	0.33 : 1 : 0
8	365	DMF	HCl (0.7 M)	1	0.38 : 1 : 0
9	365	DMF	HCl (0.9 M)	1	0.47 : 1 : 0
10	365	DMF	HCl (0.5 M)	2.5	0.25 : 1 : 0
11	365	CH3CN	HCl (0.5 M)	3	0.49 : 1 : 0.02
12	365	EtOH	HCl (0.5 M)	4	0.26 : 1 : 1.23a
13	419	EtOH	HCl (0.47 M)	0.33	2.6 : 1 : 0.35a
14	419	EtOH	HCl (0.77 M)	0.33	0.76 : 1 : 2.71a
15	419	EtOH	HCl (0.91 M)	0.33	0.74 : 1 : 1.96a
16	419	Acetal	HCl (0.77 M)	2	0 : 0 : 1a
17	419	Acetal	HCl (0.48 M)	2	0 : 0:1b
18	419	Acetal	HCl (0.16 M)	2	0 : 0 : 1b
19	419	Acetal	HCl (0.16 M)	0.66	0.08 : 0 : 1c
20	419	Acetal	HCl (0.16 M)	0.33	0.98 : 0 : 1c

^aAniline is observed in an amount of 20–30%.

^bAniline is present in an amount of ca. 10%.

^cAniline is present within an amount of 2%.