A re-investigation of the kinetics of alkaline degradation of phenyl β-d-glucopyranoside and some other glycosides

Moody, W. E.; Richards, Geoffrey N.

doi:10.1016/s0008-6215(00)80754-5

Cited by 7 publications

(11 citation statements)

References 12 publications

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“…Degradation of glycosides occurs via cleavage of their glycosidic bonds under basic condition. − In this degradation, such glycosides as glucosides and galactosides produce a considerable amount of the corresponding 1,6-anhydrosugars. − ,,, This degradation is one of the key steps in the syntheses of various glycosides and polysaccharides, because 1,6-anhydrosugars are employed as glycosyl donors in those syntheses. − Also, the degradations of such β-glycans as cellulose, glucomannan, and xylan, which are major wood components, are very industrially important, because these degradations are believed to induce undesirable depolymerization of carbohydrates in the pulp-making process. − …”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of 1,6-Anhydrosugar Formation from Phenyl d-Glucosides under Basic Condition: Reasons for Higher Reactivity of β-Anomer

et al. 2010

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Degradation of anomeric phenyl d-glucosides to levoglucosan under basic condition is theoretically studied. MP4(SDQ)//DFT(B3LYP)-computational results indicate that the degradation of phenyl α-glucoside (R(α)) occurs via the S(N)icB mechanism. In this mechanism, the oxyanion at the C6, which is formed through deprotonation of the OH group, directly attacks the anomeric carbon. On the other hand, the degradation of phenyl β-glucoside (R(β)) occurs via the S(N)icB(2) mechanism. In this mechanism, the oxyanion at the C2 attacks the anomeric carbon in a nucleophilic manner to afford 1,2-anhydride intermediate and then the oxyanion at the C6 attacks the anomeric carbon to afford levoglucosan. The activation barrier is much lower in the reaction of R(β) (ΔG(0++) = 25.6 kcal/mol and E(a) = 26.5 kcal/mol) than in the reaction of R(α) (ΔG(0++) = 38.1 kcal/mol and E(a) = 37.2 kcal/mol), which is consistent with the experimental observation that β-glucoside is generally much more reactive than the corresponding α-glucoside. The lower activation barrier of the reaction of R(β) arises from the stereoelectronic effect, which is induced by the charge transfer from the ring oxygen to the anomeric carbon, and the staggered conformation around the C1-C2 bond. When the stereoelectronic effect is absent, the degradation needs larger activation energy; for instance, the degradation of phenyl 5a-carba-β-d-glucoside (R(Cβ)) occurs with large ΔG(0++) and E(a) values like those of α-glucosides, because the methylene group of R(Cβ) does not contribute to the stereoelectronic effect. Also, the conformation around the C1-C2 bond is staggered in the transition state of the R(β) reaction but eclipsed in that of the R(α) reaction, which also leads to the larger reactivity of R(β).

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Section: Introductionmentioning

confidence: 99%

Theoretical Study of 1,6-Anhydrosugar Formation from Phenyl d-Glucosides under Basic Condition: Reasons for Higher Reactivity of β-Anomer

et al. 2010

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“…We employed here these glucosides as models of real glycosides, because these glucosides have been used as models of glycosides in many experiments. 29,39,[46][47][48] The geometry optimization was performed by the 3D-RISM-SCF-DFT method with the B3LYP functional. 63 The 6-31G(d) basis sets were used for H, C and O atoms.…”

Section: Computational Detailsmentioning

confidence: 99%

“…65 In the PCM calculation, the dielectric constant was taken to be e = 55.33 and the temperature was taken to be T = 373.15 K. 66 Before the 3D-RISM-SCF calculation, the 1D-RISM calculation was carried out to set up the solvent-solvent total correlation functions with density, r V = 0.955 g cm À3 , and temperature, T = 373.15 K. These conditions are the same as those of the experiments. 39,48 The point charges and LJ parameters of water molecules were taken from the SPC model 67 by modifying the LJ parameters of the Hw atom, (s Hw , e Hw ) = (1.0 Å, 0.056 kcal mol À1 ), 9,10 where the H and O sites of water solvent are hereafter denoted by Hw and Ow, respectively, for convenience. The 1D-RISM calculation was performed on a grid of 1024 points, which corresponds to the 1D space radius, 56.2 Å.…”

Section: Computational Detailsmentioning

confidence: 99%

A 3D-RISM-SCF method with dual solvent boxes for a highly polarized system: application to 1,6-anhydrosugar formation reaction of phenyl α- and β-d-glucosides under basic conditions

Aono

Hosoya

Sakaki

2013

Phys. Chem. Chem. Phys.

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One of the difficulties in application of the usual reference interaction site model self-consistent field (RISM-SCF) method to a highly polarized and bulky system arises from the approximate evaluation of electrostatic potential (ESP) with pure point charges. To improve this ESP evaluation, the ESP near a solute is directly calculated with a solute electronic wavefunction, that distant from a solute is approximately calculated with solute point charges, and they are connected with a switching function. To evaluate the fine solvation structure near the solute by incorporating the long-range solute-solvent Coulombic interaction with low computational cost, we introduced the dual solvent box protocol; one small box with the fine spacing is employed for the first and the second solvation shells and the other large box with the normal spacing is employed for long-range solute-solvent interaction. The levoglucosan formation from phenyl α- and β-d-glucosides under basic conditions is successfully inspected by this 3D-RISM-SCF method at the MP2 and SCS-MP2 levels, though the 1D-RISM-SCF could not be applied to this reaction due to the presence of highly polarized and bulky species. This 3D-RISM-SCF calculation reproduces the experimentally reported higher reactivity of the β-anomer. The 3D-RISM-SCF-calculated activation free energy for the β-anomer is closer to the experimental value than the PCM-calculated one. Interestingly, the solvation effect increases the difference in reactivity between these two anomers. The reason is successfully elucidated with 3D-RISM-SCF-calculated microscopic solvation structure and decomposition analysis of solute-solvent interaction.

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“…It is well known that bases can accelerate the Maillard reaction, 1 an important chemical reaction between an amino acid and a reducing sugar. Under basic conditions, degradation of glycosides can occur, [2][3][4][5][6][7][8][9][10] which is one of the key steps in the synthesis of various glycosides and polysaccharides. In addition, degradation of cellulose, glucomannan and xylan, which are major wood components, 3,11 under basic conditions, is industrially very important.…”

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confidence: 99%

Interaction and reaction of the hydroxyl ion with β-d-galactose and its hydrated complex: an ab initio molecular dynamics study

Xie

Gerber

2012

Phys. Chem. Chem. Phys.

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The interaction of OH(-) with the sugar β-D-galactose is studied computationally, with Ab Initio Molecular Dynamics (AIMD) as the prime tool. The main findings are: (1) the OH(-) abstracts a proton from the sugar in a barrier-less process, yielding H(2)O and a Deprotonated beta-d-Galactose anion, (Dep-beta-D-G)(-). (2) This reaction can be reversed when two additional H(2)O molecules are present in the sugar. (3) At 500 K, a ring-opening reaction occurs in (Dep-beta-D-G)(-) within a timescale of 10 ps. The (neutral) sugar itself is stable over this timescale, and well beyond. This indicates that OH(-) can catalyze the degradation of β-d-galactose. Implications of this process are briefly discussed.

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A re-investigation of the kinetics of alkaline degradation of phenyl β-d-glucopyranoside and some other glycosides

Cited by 7 publications

References 12 publications

Theoretical Study of 1,6-Anhydrosugar Formation from Phenyl d-Glucosides under Basic Condition: Reasons for Higher Reactivity of β-Anomer

Theoretical Study of 1,6-Anhydrosugar Formation from Phenyl d-Glucosides under Basic Condition: Reasons for Higher Reactivity of β-Anomer

A 3D-RISM-SCF method with dual solvent boxes for a highly polarized system: application to 1,6-anhydrosugar formation reaction of phenyl α- and β-d-glucosides under basic conditions

Interaction and reaction of the hydroxyl ion with β-d-galactose and its hydrated complex: an ab initio molecular dynamics study

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