Predominant formation of aromatic aldehyde and acid from a dimeric β-O-4-type lignin model compound under hydrogen peroxide bleaching conditions with high pH levels

Journal of Wood Science

Official Journal of the Japan Wood Research Society

Table 2 Recovery yield of compound 1 and yields of veratraldehyde, veratric acid, and guaiacol in the H₂O₂ and Fenton systems at a reaction time of 120 min (after 30 min from the final addition of H₂O₂)

Initial pH	Final pH	Yield based on the initial mole of compound 1 (%)^a					Yield (%)^b
Initial pH	Final pH	1E	1T	Ald^c	Acid^d	G^e	Ald^c	Acid^d	G^e
13.3	13.3	78	–	6	11	5	27	49	22
13.3	13.3	–	76	3	13	6	13	55	25
12.8	12.5	83	–	2	11	3	12	62	18
12.8	12.5	–	85	2	10	3	13	65	20
11.9	11.5	94	–	1	4	0	17	58	0
11.9	11.5	–	96	1	2	0	26	58	0
11.5	7.5	9	–	4	0	3	4	0	3
11.5	7.5	–	16	4	0	3	5	0	4
11.0	6.0	0	–	1	0	0	1	0	0
11.0	6.0	–	1	1	0	0	1	0	0
10.5	4.0	0	–	0	0	0	0	0	0
10.5	4.0	–	0	0	0	0	0	0	0
9.5	3.5	0	–	0	0	0	0	0	0
9.5	3.5	–	0	0	0	0	0	0	0
5.5	3.1	1	–	1	0	3	1	0	3
5.5	3.1	–	1	0	0	2	0	0	2

The roman, italic, and bold rows show the systems at the initially high pH levels, at the initially low pH levels, and of Fenton, respectively
^aIn case of compound 1, recovery yield is shown.
^bbased on the mole amount of disappearing compound 1 by a reaction time of 120 min
^cAld: veratraldehyde
^dAcid: veratric acid
^eG: guaiacol