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 1 Recovery yield of compound 1 and yields of veratraldehyde and guaiacol in the O₂-TMPh or O₂-Valc system

System	Yield based on the initial mole of compound 1 (%)^a								Yield (%)^b
	1E		1T		Veratraldehyde		Guaiacol		Veratraldehyde		Guaiacol
	Dis^c	360^d	Dis^c	360^d	Dis^c	360^d	Dis^c	360^d	Dis^c	360^d	Dis^c	360^d
TMPh (O₂: 1.1 MPa)^e	75	57	–	–	7	13	0^f	0^f	28	30	0^f	0^f
TMPh (O₂: 1.1 MPa)^e	–	–	81	57	5	8	0^f	0^f	26	19	0^f	0^f
TMPh (O₂: 0.4 MPa)^e	78	66	–	–	8	12	0^f	0^f	36	35	0^f	0^f
TMPh (O₂: 0.4 MPa)^e	–	–	73	61	9	13	0^f	0^f	33	34	0^f	0^f
Valc (NaOH: 0.5 mol/L)^g	85	77	–	–	5	7	2	0	33	30	13	0
Valc (NaOH: 0.5 mol/L)^g	–	–	84	75	4	5	2	0	25	20	12	0
Valc (NaOH: 0.1 mol/L)^g	93	88	–	–	2	2	1	0	27	16	14	0
Valc (NaOH: 0.1 mol/L)^g	–	–	94	88	2	2	1	0	36	17	18	0
Valc stepwise^h	–	55	–	–	–	14	–	0	–	31	–	0

^aIn case of compound 1, recovery yield is shown
^bbased on the mole amount of disappearing compound 1 by a reaction time of Dis^c or 360 min^d
^cat a reaction time when TMPh or Valc disappeared (45 min in the TMPh system under 1.1 MPa O₂, 120 min in the TMPh system under 0.4 MPa O₂, 60 min in the Valc system)
^dat a reaction time of 360 min
^eNaOH: 0.5 mol/L
^fNot exactly 0 but negligible amount
^gO₂: 1.1 MPa
^hValc was added stepwise at intervals of about 60 min. The yields displayed are not those at a reaction time of exactly 360 min. NaOH: 0.5 mol/L, O₂: 1.1 MPa