Quantitative Difference in the Rates of the β-O-4 Bond Cleavage between Lignin Model Compounds with and without γ-Hydroxymethyl Groups during the Alkaline Pulping Process

Shimizu, Soichi; Posoknistakul, Pattaraporn; Yokoyama, Tomoya; Matsumoto, Yuji

doi:10.15376/biores.8.3.4312-4322

Cited by 15 publications

(25 citation statements)

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“…3), which is an H, G, or S nucleus, respectively, is liberated almost quantitatively from the aromatic B-ring of lignin model compounds with H (GH and SH), G (GG and SG), or S nucleus as the B-ring (GS and SS), respectively. This was observed under identical reaction conditions as those employed in this study [17,18]. In this study, it was examined whether or not guaiacol is quantitatively liberated from the B-rings of HG and H Cl G. Figure 4a, b shows the time courses of the changes in the recovery yields of HG and H Cl G, respectively, and the formation of guaiacol from HG and H Cl G, respectively.…”

Section: Reaction Of Hg and H CL Gmentioning

confidence: 61%

“…The pseudofirst-order reaction rate constants were determined to be 0.0158 and 0.0177 min − 1 , respectively. Those of the other compounds were determined in our previous reports [17,18,26]. Figure 5a-d shows the HPLC chromatograms of the neutralized reaction solutions of HG, GG, SG, and H Cl G, respectively, obtained at reaction times of 150, 120, 90, and 120 min, respectively, when each of their recovery yields reached less than 15%.…”

Section: Reaction Of Hg and H CL Gmentioning

confidence: 86%

“…All the lignin model compounds except HG and H Cl G were the same as those used in our previous reports [17,18]. HG and H Cl G were synthesized, following the methods described by Alder et al [19] and in our previous reports [17,18]. Their structures and purities were confirmed by proton nuclear magnetic resonance spectroscopy ( 1 H-NMR, JNM-A500, 500 MHz, JEOL Ltd., Tokyo, Japan).…”

Section: Methodsmentioning

confidence: 99%

“…Reaction conditions were: concentration of NaOH 1.0 mol/L, initial concentration of the lignin model compound 1.2 mmol/L, temperature 150 °C, volume of the solution 5.0 mL. All procedures were identical to those described in our previous reports [17,18]. Each lignin model compound was reacted at least twice to confirm the reproducibility of the results.…”

Section: Alkaline Treatment Of the Lignin Model Compoundsmentioning

confidence: 99%

“…All work-up procedures were identical to those described in our previous reports [17,18] except those for the reaction of G -CH 2 CHO as a starting compound.…”

Section: Qualitative and Quantitative Analyses Of The Reaction Productsmentioning

confidence: 99%

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Effects of aromatic ring type on reactions subsequent to the β-O-4 bond cleavage of non-phenolic lignin model compounds under alkaline pulping conditions

et al. 2018

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The reaction products of an alkaline treatment of non-phenolic β-O-4-type lignin model compounds (C 6-C 2-type) consisting of p-hydroxyphenyl (H), guaiacyl (G), and/or syringyl (S) nuclei were identified and quantified. This was performed to examine how the type of H, G, or S nucleus affect the reaction product profiles. The major identified and quantified reaction products were phenol derivatives that were liberated from the aryl sides of the β-O-4 ether bonds of the lignin model compounds. Other products included derivatives of phenylethane-1,2-diol (glycol-type), benzaldehyde, and acetophenone, which originated from the alkyl sides of the β-O-4 ether bonds of the lignin model compounds. Although the type of aromatic nucleus of the aryl side of the β-O-4 ether bond of the lignin model compounds did not significantly affect the profile of the reaction products, the type of the alkyl side nucleus was influential. The glycol-type compound was the exclusive major reaction product when the S nucleus was on the alkyl side of the β-O-4 ether bond. On the other hand, when the H or G nucleus was present, a benzaldehyde derivative was the other major reaction product.

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Section: Reaction Of Hg and H CL Gmentioning

confidence: 61%

Section: Reaction Of Hg and H CL Gmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Alkaline Treatment Of the Lignin Model Compoundsmentioning

confidence: 99%

“…All work-up procedures were identical to those described in our previous reports [17,18] except those for the reaction of G -CH 2 CHO as a starting compound.…”

Section: Qualitative and Quantitative Analyses Of The Reaction Productsmentioning

confidence: 99%

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Effects of aromatic ring type on reactions subsequent to the β-O-4 bond cleavage of non-phenolic lignin model compounds under alkaline pulping conditions

et al. 2018

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Microwave-Assisted Conversion of Lignin

2014

Production of Biofuels and Chemicals With Microwave

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Effect of type of aromatic nucleus in lignin on the rate of the β-O-4 bond cleavage during alkaline pulping process

2015

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Several C 6 -C 3 and C 6 -C 2 -type dimeric nonphenolic b-O-4 lignin model compounds, whose aromatic nuclei consisting of the carbon skeleton and b-O-4 linkage are named the A-and B-rings, respectively, were treated under alkaline pulping conditions to examine whether or not the substitution of methoxyl group on the B-ring or of guaiacyl for syringyl A-ring accelerates the b-O-4 cleavage as a further study of our previous reports. It was suggested that either first or second substitution of methoxyl group on the B-ring accelerates the b-O-4 cleavage in both C 6 -C 3 and C 6 -C 2 compounds although the former compounds are more sensitive to the substitution than the latter, suggesting that the lack of the c-hydroxymethyl group makes model compound insensitive to the substitution. It was confirmed that the substitution of guaiacyl for syringyl A-ring accelerates the b-O-4 cleavage in both C 6 -C 3 and C 6 -C 2 compounds with the degrees similar to each other regardless of the type of the B-ring. It was clarified that the leaving ability of the leaving B-ring phenoxides in the b-O-4 cleavage does not correlate well with the pK a values of the conjugate acids of the phenoxides, which is not in accordance with the common property of a nucleophilic substitution reaction.

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Quantitative Difference in the Rates of the β-O-4 Bond Cleavage between Lignin Model Compounds with and without γ-Hydroxymethyl Groups during the Alkaline Pulping Process

Cited by 15 publications

References 0 publications

Effects of aromatic ring type on reactions subsequent to the β-O-4 bond cleavage of non-phenolic lignin model compounds under alkaline pulping conditions

Effects of aromatic ring type on reactions subsequent to the β-O-4 bond cleavage of non-phenolic lignin model compounds under alkaline pulping conditions

Microwave-Assisted Conversion of Lignin

Effect of type of aromatic nucleus in lignin on the rate of the β-O-4 bond cleavage during alkaline pulping process

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