Lignins were isolated and purified from alkali treated prehydrolysate of corn stover. The paper presents the structural features of lignins in a series purification processes. Fourier transform infrared spectroscopy, ...Lignins were isolated and purified from alkali treated prehydrolysate of corn stover. The paper presents the structural features of lignins in a series purification processes. Fourier transform infrared spectroscopy, ultraviolet-vis spectroscopy and proton nuclear magnetic resonance spectroscopy were used to analyze the chemical structure. Thermogravimetric analysis was applied to follow the thermal degradation, and wet chemical method was used to determine the sugar content. The results showed that the crude lignin from the prehydrolysate of corn stover was a heterogeneous material of syringyl, guaiacyl and p-hydroxyphenyl units, containing associated polysaccharides, lipids, and melted salts. Some of the crude lignin was chemically linked to hemicelluloses （mainly xylan）. The lipids in crude lignin were probably composed of saturated and/or unsaturated long carbon chains, fatty acids, tdterpenols, waxes, and derivatives of aromatic. The sugar content of purified lignin was less than 2.11%, mainly composed of guaiacyl units. DTGmax of purified lignin was 359 ℃. The majority of the hydroxyl groups were phenolic hydroxyl groups. The main type of linkages in purified lignin was β-O-4. Other types of linkages included β-5, β-β and α-O-4.展开更多
Hydrothermal pretreatment of poplar wood chips was performed in an acetic acid/sodium acetate buffer medium.To characterize the structural changes of lignin in the pretreatment process,milled wood lignin(MWL)was isola...Hydrothermal pretreatment of poplar wood chips was performed in an acetic acid/sodium acetate buffer medium.To characterize the structural changes of lignin in the pretreatment process,milled wood lignin(MWL)was isolated from both the un-treated and treated poplar wood chips,and analyzed by ^(1)H-NMR,^(13)C-NMR,^(31)P-NMR,FT-IR,and GPC-MALLS.Results showed that the lignin in the pretreated wood chips had more phenolic OH groups,less aliphatic OH groups,higher molecular weight,and narrower polydispersity,in comparison with the lignin in the un-treated wood.The acetic acid-sodium acetate buffer pretreatment facilitated the removal of-OCH_(3) groups and the cleavage of the inter-unit linkages ofβ-O-4 bond in the lignin.Furthermore,the re-polymerization of lignin in the acetic acid-sodium acetate buffer pretreatment was found to be less than that in autohydrolysis.展开更多
(Molecular Plant 17,112–140;January 12024)After the publication of our review paper,we became aware of errors in Figure 3.In Figure 3A,“catechyl alcohol”and“stilveno-”should be“caffeyl alcohol”and“stilbeno-”,...(Molecular Plant 17,112–140;January 12024)After the publication of our review paper,we became aware of errors in Figure 3.In Figure 3A,“catechyl alcohol”and“stilveno-”should be“caffeyl alcohol”and“stilbeno-”,respectively.In addition,“AEOMT”should be added in the step from Caffeoyl CoA to Feruloyl CoA.In the legend to Figure 3A,“hydroxycinnamic acids/hydroxycinnamoyl CoA ester O-methyltransferase”should be“hydroxycinnamic acid/hydroxycinnamoyl CoA ester O-methyltransferase”.In the Angiosperms(monocot/grasses)lignin structure in Figure 3B,the C4 side chains(trioxybutyl structure)of the 5^(th) aromatic ring from the top left end and the 3^(rd) aromatic ring from the top right end should be C_(3) side chains(trioxypropyl structure).The 4-O-4 biphenyl ether structure at the bottom of the Angiosperms(monocot/grasses)lignin structure in Figure 3B should be 4-O-5 biphenyl ether structure.In the Gymnosperms lignin structure in Figure 3B,a methoxy group should be added to the 12^(th) aromatic ring from the top left end.A corrected version of Figure 3 is shown below.The scientific conclusions of this article have not been affected by this correction.We apologize for not detecting the errors prior to publication and for any inconvenience that may have been caused.展开更多
基金Supported by the National Natural Science Foundation of China （20876078, 21176124）, the National High Technology Research and Development Program of China （2011AA02A207）, the National Basic Research Program of China （2009CB724700）, the Key Program of the National Natural Science Foundation of China （20936002）, and the Independent Innovation Project of Jiangsu Province （CX（11）2051）.
文摘Lignins were isolated and purified from alkali treated prehydrolysate of corn stover. The paper presents the structural features of lignins in a series purification processes. Fourier transform infrared spectroscopy, ultraviolet-vis spectroscopy and proton nuclear magnetic resonance spectroscopy were used to analyze the chemical structure. Thermogravimetric analysis was applied to follow the thermal degradation, and wet chemical method was used to determine the sugar content. The results showed that the crude lignin from the prehydrolysate of corn stover was a heterogeneous material of syringyl, guaiacyl and p-hydroxyphenyl units, containing associated polysaccharides, lipids, and melted salts. Some of the crude lignin was chemically linked to hemicelluloses （mainly xylan）. The lipids in crude lignin were probably composed of saturated and/or unsaturated long carbon chains, fatty acids, tdterpenols, waxes, and derivatives of aromatic. The sugar content of purified lignin was less than 2.11%, mainly composed of guaiacyl units. DTGmax of purified lignin was 359 ℃. The majority of the hydroxyl groups were phenolic hydroxyl groups. The main type of linkages in purified lignin was β-O-4. Other types of linkages included β-5, β-β and α-O-4.
基金support from the National Natural Science Foundation of China (31540009 and 31370581)the Yellow River Mouth Scholar Program (DYRC20120105).
文摘Hydrothermal pretreatment of poplar wood chips was performed in an acetic acid/sodium acetate buffer medium.To characterize the structural changes of lignin in the pretreatment process,milled wood lignin(MWL)was isolated from both the un-treated and treated poplar wood chips,and analyzed by ^(1)H-NMR,^(13)C-NMR,^(31)P-NMR,FT-IR,and GPC-MALLS.Results showed that the lignin in the pretreated wood chips had more phenolic OH groups,less aliphatic OH groups,higher molecular weight,and narrower polydispersity,in comparison with the lignin in the un-treated wood.The acetic acid-sodium acetate buffer pretreatment facilitated the removal of-OCH_(3) groups and the cleavage of the inter-unit linkages ofβ-O-4 bond in the lignin.Furthermore,the re-polymerization of lignin in the acetic acid-sodium acetate buffer pretreatment was found to be less than that in autohydrolysis.
文摘(Molecular Plant 17,112–140;January 12024)After the publication of our review paper,we became aware of errors in Figure 3.In Figure 3A,“catechyl alcohol”and“stilveno-”should be“caffeyl alcohol”and“stilbeno-”,respectively.In addition,“AEOMT”should be added in the step from Caffeoyl CoA to Feruloyl CoA.In the legend to Figure 3A,“hydroxycinnamic acids/hydroxycinnamoyl CoA ester O-methyltransferase”should be“hydroxycinnamic acid/hydroxycinnamoyl CoA ester O-methyltransferase”.In the Angiosperms(monocot/grasses)lignin structure in Figure 3B,the C4 side chains(trioxybutyl structure)of the 5^(th) aromatic ring from the top left end and the 3^(rd) aromatic ring from the top right end should be C_(3) side chains(trioxypropyl structure).The 4-O-4 biphenyl ether structure at the bottom of the Angiosperms(monocot/grasses)lignin structure in Figure 3B should be 4-O-5 biphenyl ether structure.In the Gymnosperms lignin structure in Figure 3B,a methoxy group should be added to the 12^(th) aromatic ring from the top left end.A corrected version of Figure 3 is shown below.The scientific conclusions of this article have not been affected by this correction.We apologize for not detecting the errors prior to publication and for any inconvenience that may have been caused.
