Mechanism of the self-condensation of GlcNH2: insights from in situ NMR spectroscopy and DFT study

Lingyu Jia; Xingchen Liu; Yan Qiao; Christian Marcus Pedersen; Zhenzhou Zhang; Hui-Juan Ge; Zhihong Wei; Yanyan Chen; Xiaodong Wen; Xianglin Hou; Yingxiong Wang

doi:10.1016/j.apcatb.2016.09.058

Mechanism of the self-condensation of GlcNH₂: insights from in situ NMR spectroscopy and DFT study

Lingyu Jia, Xingchen Liu, Yan Qiao, Christian Marcus Pedersen, Zhenzhou Zhang, Hui-Juan Ge, Zhihong Wei, Yanyan Chen, Xiaodong Wen, Xianglin Hou, Yingxiong Wang

Department of Chemistry

17 Citations (Scopus)

Abstract

A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of d-Glucosamine (GlcNH2) to deoxyfructosazine (DOF) and fructosazine (FZ) was performed. The pathways for the formation of DOF and FZ via self-condensation of GlcNH2 were investigated by in situ13C NMR using site-selectively 13C-labeled GlcNH2. The structural characterization of the reactive species by ESI–MS spectrometry combined with NMR analysis of [13C-1]GlcNH2 indicates that the first carbon (C-1) of GlcNH2 maps onto the corresponding ring carbons of the intermediate, called dihydrofructosazine [2,5-bis(d-arabino-tetrahydroxybutyl)dihydropyrazine], which subsequently is converted to the corresponding pyrazine ring carbons of DOF and FZ respectively. The isotopic-labelling experiments disclose that there are two parallel reaction pathways open to the intermediate dihydrofructosazine, when the reaction takes place in DMSO with [C2C1Im][OAc] as catalyst. The theoretical results from DFT calculation indicate that the role of the imidazolium based ILs [C2C1Im][OAc] can be envisaged as an acid-base dual activation in catalyzing DOF and FZ formation. It turns out that the acidic cation center exerted significant influences on the energy barriers associated with dehydration reaction. In addition, a critical role of counteranion AcO− is to facilitate dehydrogenation process, leading to the formation of hydrogen. A comparison between the two reaction channels, after the formation of intermediate dihydrofructosazine, indicates that both pathways are plausible and that the pathway to DOF is thermodynamically more favorable than that to FZ. The theoretical results are consistent with the experimental observations, and therefore, a detailed and reasonable reaction mechanism was proposed

Original language	English
Journal	Applied Catalysis B: Environmental
Volume	202
Pages (from-to)	420-429
Number of pages	10
ISSN	0926-3373
DOIs	https://doi.org/10.1016/j.apcatb.2016.09.058
Publication status	Published - 1 Mar 2017

Keywords

in situ NMR
DFT calculations
Reaction mechanism
Chitin biomass

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10.1016/j.apcatb.2016.09.058

Cite this

@article{c189616637e04ed09a6927b1161a9621,

title = "Mechanism of the self-condensation of GlcNH2: insights from in situ NMR spectroscopy and DFT study",

abstract = "A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of d-Glucosamine (GlcNH2) to deoxyfructosazine (DOF) and fructosazine (FZ) was performed. The pathways for the formation of DOF and FZ via self-condensation of GlcNH2 were investigated by in situ13C NMR using site-selectively 13C-labeled GlcNH2. The structural characterization of the reactive species by ESI–MS spectrometry combined with NMR analysis of [13C-1]GlcNH2 indicates that the first carbon (C-1) of GlcNH2 maps onto the corresponding ring carbons of the intermediate, called dihydrofructosazine [2,5-bis(d-arabino-tetrahydroxybutyl)dihydropyrazine], which subsequently is converted to the corresponding pyrazine ring carbons of DOF and FZ respectively. The isotopic-labelling experiments disclose that there are two parallel reaction pathways open to the intermediate dihydrofructosazine, when the reaction takes place in DMSO with [C2C1Im][OAc] as catalyst. The theoretical results from DFT calculation indicate that the role of the imidazolium based ILs [C2C1Im][OAc] can be envisaged as an acid-base dual activation in catalyzing DOF and FZ formation. It turns out that the acidic cation center exerted significant influences on the energy barriers associated with dehydration reaction. In addition, a critical role of counteranion AcO− is to facilitate dehydrogenation process, leading to the formation of hydrogen. A comparison between the two reaction channels, after the formation of intermediate dihydrofructosazine, indicates that both pathways are plausible and that the pathway to DOF is thermodynamically more favorable than that to FZ. The theoretical results are consistent with the experimental observations, and therefore, a detailed and reasonable reaction mechanism was proposed",

keywords = "in situ NMR, DFT calculations, Reaction mechanism, Chitin biomass",

author = "Lingyu Jia and Xingchen Liu and Yan Qiao and Pedersen, {Christian Marcus} and Zhenzhou Zhang and Hui-Juan Ge and Zhihong Wei and Yanyan Chen and Xiaodong Wen and Xianglin Hou and Yingxiong Wang",

year = "2017",

month = mar,

day = "1",

doi = "10.1016/j.apcatb.2016.09.058",

language = "English",

volume = "202",

pages = "420--429",

journal = "Applied Catalysis B: Environmental",

issn = "0926-3373",

publisher = "Elsevier",

}

TY - JOUR

T1 - Mechanism of the self-condensation of GlcNH2

T2 - insights from in situ NMR spectroscopy and DFT study

AU - Jia, Lingyu

AU - Liu, Xingchen

AU - Qiao, Yan

AU - Pedersen, Christian Marcus

AU - Zhang, Zhenzhou

AU - Ge, Hui-Juan

AU - Wei, Zhihong

AU - Chen, Yanyan

AU - Wen, Xiaodong

AU - Hou, Xianglin

AU - Wang, Yingxiong

PY - 2017/3/1

Y1 - 2017/3/1

N2 - A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of d-Glucosamine (GlcNH2) to deoxyfructosazine (DOF) and fructosazine (FZ) was performed. The pathways for the formation of DOF and FZ via self-condensation of GlcNH2 were investigated by in situ13C NMR using site-selectively 13C-labeled GlcNH2. The structural characterization of the reactive species by ESI–MS spectrometry combined with NMR analysis of [13C-1]GlcNH2 indicates that the first carbon (C-1) of GlcNH2 maps onto the corresponding ring carbons of the intermediate, called dihydrofructosazine [2,5-bis(d-arabino-tetrahydroxybutyl)dihydropyrazine], which subsequently is converted to the corresponding pyrazine ring carbons of DOF and FZ respectively. The isotopic-labelling experiments disclose that there are two parallel reaction pathways open to the intermediate dihydrofructosazine, when the reaction takes place in DMSO with [C2C1Im][OAc] as catalyst. The theoretical results from DFT calculation indicate that the role of the imidazolium based ILs [C2C1Im][OAc] can be envisaged as an acid-base dual activation in catalyzing DOF and FZ formation. It turns out that the acidic cation center exerted significant influences on the energy barriers associated with dehydration reaction. In addition, a critical role of counteranion AcO− is to facilitate dehydrogenation process, leading to the formation of hydrogen. A comparison between the two reaction channels, after the formation of intermediate dihydrofructosazine, indicates that both pathways are plausible and that the pathway to DOF is thermodynamically more favorable than that to FZ. The theoretical results are consistent with the experimental observations, and therefore, a detailed and reasonable reaction mechanism was proposed

AB - A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of d-Glucosamine (GlcNH2) to deoxyfructosazine (DOF) and fructosazine (FZ) was performed. The pathways for the formation of DOF and FZ via self-condensation of GlcNH2 were investigated by in situ13C NMR using site-selectively 13C-labeled GlcNH2. The structural characterization of the reactive species by ESI–MS spectrometry combined with NMR analysis of [13C-1]GlcNH2 indicates that the first carbon (C-1) of GlcNH2 maps onto the corresponding ring carbons of the intermediate, called dihydrofructosazine [2,5-bis(d-arabino-tetrahydroxybutyl)dihydropyrazine], which subsequently is converted to the corresponding pyrazine ring carbons of DOF and FZ respectively. The isotopic-labelling experiments disclose that there are two parallel reaction pathways open to the intermediate dihydrofructosazine, when the reaction takes place in DMSO with [C2C1Im][OAc] as catalyst. The theoretical results from DFT calculation indicate that the role of the imidazolium based ILs [C2C1Im][OAc] can be envisaged as an acid-base dual activation in catalyzing DOF and FZ formation. It turns out that the acidic cation center exerted significant influences on the energy barriers associated with dehydration reaction. In addition, a critical role of counteranion AcO− is to facilitate dehydrogenation process, leading to the formation of hydrogen. A comparison between the two reaction channels, after the formation of intermediate dihydrofructosazine, indicates that both pathways are plausible and that the pathway to DOF is thermodynamically more favorable than that to FZ. The theoretical results are consistent with the experimental observations, and therefore, a detailed and reasonable reaction mechanism was proposed

KW - in situ NMR

KW - DFT calculations

KW - Reaction mechanism

KW - Chitin biomass

U2 - 10.1016/j.apcatb.2016.09.058

DO - 10.1016/j.apcatb.2016.09.058

M3 - Journal article

SN - 0926-3373

VL - 202

SP - 420

EP - 429

JO - Applied Catalysis B: Environmental

JF - Applied Catalysis B: Environmental

ER -