Insights into the Cr(<scp>iii</scp>) catalyzed isomerization mechanism of glucose to fructose in the presence of water using ab initio molecular dynamics

Mushrif, Samir H.; Varghese, Jithin John; Vlachos, Dionisios G.

doi:10.1039/c4cp02095b

Cited by 61 publications

(76 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12), also slows down the kinetics of side reactions and helps achieve better selectivity for the dehydration reaction. Recent investigations into CrCl 3 catalyzed glucose to fructose isomerization were performed by Mushrif et al (2014), using CPMDmetadynamics, with explicit water molecules. They demonstrated that, contrary to popular belief that the hexahydrated Cr 3 þ is the active species, the partially hydrolyzed [Cr(H 2 O) 5 OH] 2 þ complex is the active isomerization species.…”

Section: Solvent Effects On Biomass Conversion Reactionsmentioning

confidence: 99%

See 1 more Smart Citation

Multiscale molecular modeling can be an effective tool to aid the development of biomass conversion technology: A perspective

Mushrif

Vasudevan

Krishnamurthy

et al. 2015

Chemical Engineering Science

Self Cite

View full text Add to dashboard Cite

Section: Solvent Effects On Biomass Conversion Reactionsmentioning

confidence: 99%

“…The free energy barrier for the reaction is 104 kJ/mol. The free energy surface is constructed as a function of two reaction coordinates (Mushrif et al, 2014).…”

Section: Perspective and Future Directionsmentioning

confidence: 99%

Multiscale molecular modeling can be an effective tool to aid the development of biomass conversion technology: A perspective

Mushrif

Vasudevan

Krishnamurthy

et al. 2015

Chemical Engineering Science

Self Cite

View full text Add to dashboard Cite

“…45 It has been shown that the protonation of glucose at C 2 oxygen (carbon atom numbering same as shown in Table 2) leads to the formation of HMF, while the protonation of the oxygen attached to C 3 and C 4 leads to other dehydration/rehydration products. 19,50 For both condensation and dehydration products to be formed, water molecules need to be present in the immediate vicinity of the specic oxygen atom so that proton can be transferred from water to that oxygen atom. Qian et al have done a series of studies using Car-Parrinello molecular dynamics to study the conversion of glucose via different dehydration and condensation pathways by protonation of different oxygens.…”

Section: Atomic Details Of the Positioning Of Solvents Around Glucosementioning

confidence: 99%

Insights into the solvation of glucose in water, dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) and its possible implications on the conversion of glucose to platform chemicals

2015

Self Cite

View full text Add to dashboard Cite

Cellulosic biomass derived molecules such as glucose can be converted into specific platform chemicals like 5-hydroxymethylfurfural (HMF), levulinic acid and gamma valerolactone (GVL). The solvation medium plays an important role in the selective conversion of glucose to these platform chemicals and it is shown that the addition of co-solvents increases the selectivity towards desired products and minimizes the formation of undesired condensation/polymerization products and humins. Hence, it becomes imperative to understand the implications of the solvation of glucose by co-solvents on glucose conversion reactions. In the present paper, we implement OPLS-AA force-field based molecular dynamics simulations to investigate the solvation of glucose in water, in the presence of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF) and tetrahydrofuran (THF). The local arrangement of solvents around the glucose molecule is analyzed using 2-dimensional radial pair distribution functions and 3-dimensional volumetric maps. Additionally, lifetimes and activation free energies of hydrogen bonds between solvents and glucose and the tendency of glucose molecules to agglomerate were studied. It was observed that all the aforementioned co-solvents compete with water to be in the first solvation shell of glucose and significant amount of water is pushed to the second coordination shell.Though fewer water molecules are directly coordinated with glucose in the presence of co-solvents, they are bound strongly to it. Additionally, DMSO, THF and DMF tend to localize more around the hydrogen atom of the hydroxyl groups of selected carbon atoms of glucose. This preferential arrangement of co-solvents and water around glucose may play a role in facilitating the reaction pathway for the formation of HMF and levulinic acid and may reduce the likelihood of glucose' degradation to unwanted dehydration/rehydration products. Increasing the proportion of co-solvents also increases the hydrogen bond lifetimes between water and glucose and reduces the mobility of glucose molecules within the solvent. The reduced mobility of glucose molecules in the presence of cosolvents might be correlated to the experimentally observed reduction in the rate of formation of polymerization/condensation products and humins. † Electronic supplementary information (ESI) available: Centre of mass RDFs for glucose-co-solvents, co-solvent-water and water-water pairs are provided. See

show abstract

“…[1][2][3][4][5][6][7][8][9] Since cellulosic biomass and its sugar derivatives are solid species, these reactions are performed in a solvent medium. [1][2][3][4][5][6][7][8][9] Since cellulosic biomass and its sugar derivatives are solid species, these reactions are performed in a solvent medium.…”

Section: Introductionmentioning

confidence: 99%

Solvation dynamics and energetics of intramolecular hydride transfer reactions in biomass conversion

Mushrif

Varghese

Krishnamurthy

2015

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

Hydride transfer changes the charge structure of the reactant and thus, may induce reorientation/reorganization of solvent molecules. This solvent reorganization may in turn alter the energetics of the reaction. In the present work, we investigate the intramolecular hydride transfer by taking Lewis acid catalyzed glucose to fructose isomerization as an example. The C2-C1 hydride transfer is the rate limiting step in this reaction. Water and methanol are used as solvents and hydride transfer is simulated in the presence of explicit solvent molecules, treated quantum mechanically and at a finite temperature, using Car-Parrinello molecular dynamics (CPMD) and metadynamics. Activation free energy barrier for hydride transfer in methanol is found to be 50 kJ mol(-1) higher than that in water. In contrast, in density functional theory calculations, using an implicit solvent environment, the barriers are almost identical. Analysis of solvent dynamics and electronic polarization along the molecular dynamics trajectory and the results of CPMD-metadynamics simulation of the hydride transfer process in the absence of any solvent suggest that higher barrier in methanol is a result of non-equilibrium solvation. Methanol undergoes electronic polarization during the hydride transfer step. However, its molecular orientational relaxation is a much slower process that takes place after the hydride transfer, over an extended timescale. This results in non-equilibrium solvation. Water, on the other hand, does not undergo significant electronic polarization and thus, has to undergo minimal molecular reorientation to provide near equilibrium solvation to the transition state and an improved equilibrium solvation to the post hydride shift product state. Hence, the hydride transfer step is also observed to be exergonic in water and endergonic in methanol. The aforementioned explanation is juxtaposed to enzyme catalyzed charge transfer reactions, where the enhanced solvation of the transition and product states by enzymes, due to electrostatic interactions, reduces the activation free energy barrier and the free energy change of the reaction. Similarly, we suggest that, in the intramolecular hydride shift, improved solvation of the transition state and of the product state by water is achieved due to minimal polarization and reorientation, and (near) equilibrium solvation.

show abstract

Insights into the Cr(iii) catalyzed isomerization mechanism of glucose to fructose in the presence of water using ab initio molecular dynamics

Cited by 61 publications

References 39 publications

Multiscale molecular modeling can be an effective tool to aid the development of biomass conversion technology: A perspective

Multiscale molecular modeling can be an effective tool to aid the development of biomass conversion technology: A perspective

Insights into the solvation of glucose in water, dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) and its possible implications on the conversion of glucose to platform chemicals

Solvation dynamics and energetics of intramolecular hydride transfer reactions in biomass conversion

Contact Info

Product

Resources

About