Chemical and morphological characterization of sugarcane bagasse submitted to a delignification process for enhanced enzymatic digestibility

Table 2 Assignments of NMR lines 1 to 17 indicated on the spectrum in Figure 2a.

Line number	Chemical group	¹³C chemical shift (ppm)
1	CH₃ in acetyl groups of hemicelluloses	21.5
2	Aryl methoxyl carbons of lignin	56.2
3	C6 carbon of non-crystalline cellulose, C6 carbon of hemicelluloses, OC_γH₂ carbons of lignin	62.5
4	C6 carbon of crystalline cellulose	64.8
5	C2,3,5 of cellulose, OC_αH₂ carbons of lignin	72.5
6	C2,3,5 of cellulose and hemicelluloses	74.4
7	C4 carbon of non-crystalline cellulose and hemicelluloses, OC_βH₂ carbons of lignin	83.5
8	C4 carbon of crystalline cellulose	87.9
9	Shoulder of C1 carbon of hemicelluloses	101.8
10	C1 carbon of cellulose	105.0
11	C2 and C6 aromatic carbons of syringyl and C5 and C6 aromatic carbons of guaiacyl in lignin	110-115
12	C2 of aromatic carbons guaiacyl in lignin	126.6
13	C1 and C4 aromatic carbons of syringyl (e)	134.5
13	C1 and C4 aromatic carbons of syringyl (ne)	136.9
14	C3 and C5 aromatic carbons of syringyl (ne) and C1 and C4 aromatic carbons of guaiacyl in lignin	148.0
15	C3 and C5 aromatic carbons of syringyl (e) in lignin	153.5
16	Carboxyl groups of lignin	163.0-180.0
17	Carboxyl groups of hemicelluloses	173.6

These assignments were based on published data [38, 39] and also on the results of the spectral editing experiments described in the experimental section [40, 41]. ne: nonetherified arylglycerol β-aryl ethers; e: etherified arylglycerol β-aryl ethers.

ISSN: 2731-3654