DFT Analyses of Reaction Pathways and Temperature Effects on various Guaiacol Conversion Reactions in Gas Phase Environment

Verma, Anand Mohan; Kishore, Nanda

doi:10.1002/slct.201601139

Cited by 25 publications

(22 citation statements)

References 44 publications

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“…On comparison with studies conducted in the gas phase with B3LYP functional by Huang et al . and Verma and Kishore, it can be observed that the BDE requirement for guaiacol increases in the aqueous medium (see Table of supplementary information). But since the functional used in their studies is different than this study, any quantitative comparison cannot be concluded with certainty.…”

Section: Bond Dissociation Energy (Bde)mentioning

confidence: 51%

“…CH 3 from methoxy group to produce structure 2_a which is then hydrogenated to produce catechol (structure 2_b ) exothermally as seen from its PES shown in Figure . The hydrogenation of structure 2_a to catechol releases 83.34 kcal/mol of energy in the aqueous phase which is about 8 kcal/mol higher than the gas phase . The cleavage of hydroxyl group from catechol to produce structure 2_c requires very high activation energy of 116.07 kcal/mol which makes this conversion feasible at high‐temperature conditions only.…”

Section: Resultsmentioning

confidence: 99%

“…The formation of anisole from guaiacol can occur via RS 5 and RS 5a . The cleavage of the hydroxyl group from guaiacol to produce structure 5_a requires 111.26 kcal/mol which is slightly higher than in the gas phase . This is followed by hydrogenation to liberate 114.57 kcal/mol producing anisole via reaction Scheme ( RS 5 ), whereas in reaction Scheme a ( RS 5a ), guaiacol is hydrogenated with only 6.67 kcal/mol of energy to produce structure 5_a1 .…”

Section: Resultsmentioning

confidence: 99%

“…This makes it a suitable representative compound to study deoxygenation for the production of several platform chemicals. Thus, extensive study has been conducted towards guaiacol deoxygenation both experimentally and computationally ,. Some of them are detailed below.…”

Section: Introductionmentioning

confidence: 99%

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Thermochemical Conversion of Guaiacol in Aqueous Phase by Density Functional Theory

2019

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The conversion of guaiacol to benzene, toluene and o‐cresol along with several important intermediates like phenol, catechol and others in aqueous phase has been theoretically studied under the framework of density functional theory (DFT). The bond dissociation energy (BDE) calculation has been performed on optimized structures of guaiacol, phenol and anisole; and accordingly several reaction pathways have been proposed. The thermochemical parameters like Gibb's free energy change and enthalpy change of the reactions have also been reported using M06‐2X functional. In BDE study of the three compounds, i. e., guaiacol, phenol and anisole, it is observed that the scission of H. at fifth carbon position of an aromatic ring is the highest energy demanding dissociation, whereas the cleavage of bond from the functional group attached to the aromatic ring has the least BDE. The formation of phenol from guaiacol is more likely to occur by simultaneous hydrogenation and demethoxylation of guaiacol amongst all proposed pathways in aqueous phase. Further, decomposition of phenol to benzene is likely to occur via direct dehydroxylation of phenol. The simultaneous hydrogenation and dehydroxylation of guaiacol in aqueous phase are most likely to produce anisole which can further be reduced to phenol by direct cleavage of methyl group followed by hydrogenation. Further, free energy change landscape shows the conversion of guaiacol to phenol to be kinetically most favourable conversion at low temperature and high pressure in the aqueous phase. Finally, the increase in temperature causes a decrease in Gibb's free energy change and enthalpy change of overall reactions, thereby increasing favourability of most of the reactions in aqueous phase. Furthermore, the comparison between gaseous and aqueous phase results have been made wherever applicable.

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Section: Bond Dissociation Energy (Bde)mentioning

confidence: 51%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermochemical Conversion of Guaiacol in Aqueous Phase by Density Functional Theory

2019

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“…In addition to kinetic studies, also adsorption studies [48], theoretical DFT (density function theory) calculations [22,[71][72][73][74][75] and bond dissociation energy calculations [36] have been performed.…”

Section: Reaction Pathways and The Thermodynamic Feasibility Of Diffementioning

confidence: 99%

Hydrodeoxygenation of Lignin-Derived Phenols: From Fundamental Studies towards Industrial Applications

Mäki‐Arvela

Murzin

2017

Catalysts

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Hydrodeoxygenation (HDO) of bio-oils, lignin and their model compounds is summarized in this review. The main emphasis is put on elucidating the reaction network, catalyst stability and time-on-stream behavior, in order to better understand the prerequisite for industrial utilization of biomass in HDO to produce fuels and chemicals. The results have shown that more oxygenated feedstock, selection of temperature and pressure as well as presence of certain catalyst poisons or co-feed have a prominent role in the HDO of real biomass. Theoretical considerations, such as density function theory (DFT) calculations, were also considered, giving scientific background for the further development of HDO of real biomass.

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Production of Benzene from 2‐Hydroxybenzaldehyde by Various Reaction Paths using IRC Calculations within a DFT framework

Verma

Kishore

2017

ChemistrySelect

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The bio‐oil produced from pyrolysis of lignocellulosic biomass comprises of several oxy‐catalogues such as acids, alcohols, aldehydes, furans, phenols, etc. The oxy‐functionals in the bio‐oils vitiate the quality of bio‐oil, therefore, the unprocessed bio‐oils cannot be used directly to transportation vehicles. In this work, 2‐hydroxybenzaldehyde (2‐HB) has been taken as bio‐oil model component and carried out seven reaction pathways to produce benzene and other important intermediate products such as phenol, benzaldehyde, etc. The first reaction pathway is about the cleavage of formyl group of 2‐HB followed by single step hydrogenation reaction to produce phenol which further produces benzene component. The reaction pathway 2 is the hydrogen migration reaction followed by cleavage of formyl group and the reaction pathway 3 is decarbonylation reaction of 2‐hydroxybenzaldehyde to produce phenol component. The reaction pathway 4 is single atom hydrogenation at the aromatic carbon of Caromatic‐CHO sigma bond followed by the removal of formyl group to produce phenol. Similarly, the reaction pathway 5 starts with a single atom hydrogenation at the aromatic carbon of Caromatic‐OH sigma bond followed by hydroxyl group removal to produce benzaldehyde component. The reaction pathway 6 is the dehydrogenation reaction of formyl group followed by CO removal and a single step hydrogenation to produce phenol. The reaction pathway 7 directly cleaves the hydroxyl functional followed by hydrogenation reaction to produce benzaldehyde which further follows two sub‐pathways to produce benzene. The direct cleavages of hydroxyl and formyl functionals are not favourable as they require very high amount of energetics. Instead, the single atom hydrogenation to the aromatic carbon of Caromatic‐X (X=•OH or •CHO) followed by the oxy‐functional removal is found to be favourable reaction pathway.

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DFT Analyses of Reaction Pathways and Temperature Effects on various Guaiacol Conversion Reactions in Gas Phase Environment

Cited by 25 publications

References 44 publications

Thermochemical Conversion of Guaiacol in Aqueous Phase by Density Functional Theory

Thermochemical Conversion of Guaiacol in Aqueous Phase by Density Functional Theory

Hydrodeoxygenation of Lignin-Derived Phenols: From Fundamental Studies towards Industrial Applications

Production of Benzene from 2‐Hydroxybenzaldehyde by Various Reaction Paths using IRC Calculations within a DFT framework

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