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Koop Lammertsma - One of the best experts on this subject based on the ideXlab platform.
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Protonation enthalpies in Fluorosulfonic Acid using ab initio self‐consistent reaction field theory
Journal of Computational Chemistry, 1998Co-Authors: Nathan J Harris, Tomohiko Ohwada, Koop LammertsmaAbstract:Electrostatic solvation free energies were computed for several small neutral bases and their conjugate Acids using a continuum solvation model called the self-consistent isodensity polarizable continuum model (SCIPCM). The solvation energies were computed at the restricted Hartree–Fock (RHF) and second-order Moller–Plesset (MP2) levels of theory, as well as with the Becke3–Lee–Yang–Parr (B3LYP) density functional theory, using the standard 6–31G** Gaussian basis set. The RHF solvation energies are similar to those computed at the correlated MP2 and B3LYP theoretical levels. A model for computing protonation enthalpies for neutral bases in Fluorosulfonic Acid solvent leads to the equation ΔH(B)=−PA(B)+ΔEt(BH+)−ΔEt(B)+β, where PA(B) is the gas phase proton affinity for base B, ΔEt(BH+) is the SCIPCM solvation energy for the conjugate Acid, and ΔEt(B) is the solvation energy for the base. A fit to experimental values of ΔH(B) for 10 neutral bases (H2O, MeOH, Me2O, H2S, MeSH, Me2S, NH3, MeNH2, Me2NH, and PH3) gives β=238.4±2.9 kcal/mol when ΔΔEt is computed using the 0.0004 e⋅bohr−3 isodensity surface for defining the solute cavity at the RHF/6–31G** level. The model predicts that for carbon monoxide ΔH(CO)=10 kcal/mol. Thus, protonation of CO is endothermic, and the conjugate Acid HCO+ (formyl cation) behaves as a strong Acid in Fluorosulfonic Acid. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 250–257, 1998
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protonation enthalpies in Fluorosulfonic Acid using ab initio self consistent reaction field theory
Journal of Computational Chemistry, 1998Co-Authors: Tomohiko Ohwada, Koop Lammertsma, Nathan J HarrisAbstract:Electrostatic solvation free energies were computed for several small neutral bases and their conjugate Acids using a continuum solvation model called the self-consistent isodensity polarizable continuum model (SCIPCM). The solvation energies were computed at the restricted Hartree–Fock (RHF) and second-order Moller–Plesset (MP2) levels of theory, as well as with the Becke3–Lee–Yang–Parr (B3LYP) density functional theory, using the standard 6–31G** Gaussian basis set. The RHF solvation energies are similar to those computed at the correlated MP2 and B3LYP theoretical levels. A model for computing protonation enthalpies for neutral bases in Fluorosulfonic Acid solvent leads to the equation ΔH(B)=−PA(B)+ΔEt(BH+)−ΔEt(B)+β, where PA(B) is the gas phase proton affinity for base B, ΔEt(BH+) is the SCIPCM solvation energy for the conjugate Acid, and ΔEt(B) is the solvation energy for the base. A fit to experimental values of ΔH(B) for 10 neutral bases (H2O, MeOH, Me2O, H2S, MeSH, Me2S, NH3, MeNH2, Me2NH, and PH3) gives β=238.4±2.9 kcal/mol when ΔΔEt is computed using the 0.0004 e⋅bohr−3 isodensity surface for defining the solute cavity at the RHF/6–31G** level. The model predicts that for carbon monoxide ΔH(CO)=10 kcal/mol. Thus, protonation of CO is endothermic, and the conjugate Acid HCO+ (formyl cation) behaves as a strong Acid in Fluorosulfonic Acid. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 250–257, 1998
Nathan J Harris - One of the best experts on this subject based on the ideXlab platform.
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Protonation enthalpies in Fluorosulfonic Acid using ab initio self‐consistent reaction field theory
Journal of Computational Chemistry, 1998Co-Authors: Nathan J Harris, Tomohiko Ohwada, Koop LammertsmaAbstract:Electrostatic solvation free energies were computed for several small neutral bases and their conjugate Acids using a continuum solvation model called the self-consistent isodensity polarizable continuum model (SCIPCM). The solvation energies were computed at the restricted Hartree–Fock (RHF) and second-order Moller–Plesset (MP2) levels of theory, as well as with the Becke3–Lee–Yang–Parr (B3LYP) density functional theory, using the standard 6–31G** Gaussian basis set. The RHF solvation energies are similar to those computed at the correlated MP2 and B3LYP theoretical levels. A model for computing protonation enthalpies for neutral bases in Fluorosulfonic Acid solvent leads to the equation ΔH(B)=−PA(B)+ΔEt(BH+)−ΔEt(B)+β, where PA(B) is the gas phase proton affinity for base B, ΔEt(BH+) is the SCIPCM solvation energy for the conjugate Acid, and ΔEt(B) is the solvation energy for the base. A fit to experimental values of ΔH(B) for 10 neutral bases (H2O, MeOH, Me2O, H2S, MeSH, Me2S, NH3, MeNH2, Me2NH, and PH3) gives β=238.4±2.9 kcal/mol when ΔΔEt is computed using the 0.0004 e⋅bohr−3 isodensity surface for defining the solute cavity at the RHF/6–31G** level. The model predicts that for carbon monoxide ΔH(CO)=10 kcal/mol. Thus, protonation of CO is endothermic, and the conjugate Acid HCO+ (formyl cation) behaves as a strong Acid in Fluorosulfonic Acid. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 250–257, 1998
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protonation enthalpies in Fluorosulfonic Acid using ab initio self consistent reaction field theory
Journal of Computational Chemistry, 1998Co-Authors: Tomohiko Ohwada, Koop Lammertsma, Nathan J HarrisAbstract:Electrostatic solvation free energies were computed for several small neutral bases and their conjugate Acids using a continuum solvation model called the self-consistent isodensity polarizable continuum model (SCIPCM). The solvation energies were computed at the restricted Hartree–Fock (RHF) and second-order Moller–Plesset (MP2) levels of theory, as well as with the Becke3–Lee–Yang–Parr (B3LYP) density functional theory, using the standard 6–31G** Gaussian basis set. The RHF solvation energies are similar to those computed at the correlated MP2 and B3LYP theoretical levels. A model for computing protonation enthalpies for neutral bases in Fluorosulfonic Acid solvent leads to the equation ΔH(B)=−PA(B)+ΔEt(BH+)−ΔEt(B)+β, where PA(B) is the gas phase proton affinity for base B, ΔEt(BH+) is the SCIPCM solvation energy for the conjugate Acid, and ΔEt(B) is the solvation energy for the base. A fit to experimental values of ΔH(B) for 10 neutral bases (H2O, MeOH, Me2O, H2S, MeSH, Me2S, NH3, MeNH2, Me2NH, and PH3) gives β=238.4±2.9 kcal/mol when ΔΔEt is computed using the 0.0004 e⋅bohr−3 isodensity surface for defining the solute cavity at the RHF/6–31G** level. The model predicts that for carbon monoxide ΔH(CO)=10 kcal/mol. Thus, protonation of CO is endothermic, and the conjugate Acid HCO+ (formyl cation) behaves as a strong Acid in Fluorosulfonic Acid. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 250–257, 1998
Tomohiko Ohwada - One of the best experts on this subject based on the ideXlab platform.
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Protonation enthalpies in Fluorosulfonic Acid using ab initio self‐consistent reaction field theory
Journal of Computational Chemistry, 1998Co-Authors: Nathan J Harris, Tomohiko Ohwada, Koop LammertsmaAbstract:Electrostatic solvation free energies were computed for several small neutral bases and their conjugate Acids using a continuum solvation model called the self-consistent isodensity polarizable continuum model (SCIPCM). The solvation energies were computed at the restricted Hartree–Fock (RHF) and second-order Moller–Plesset (MP2) levels of theory, as well as with the Becke3–Lee–Yang–Parr (B3LYP) density functional theory, using the standard 6–31G** Gaussian basis set. The RHF solvation energies are similar to those computed at the correlated MP2 and B3LYP theoretical levels. A model for computing protonation enthalpies for neutral bases in Fluorosulfonic Acid solvent leads to the equation ΔH(B)=−PA(B)+ΔEt(BH+)−ΔEt(B)+β, where PA(B) is the gas phase proton affinity for base B, ΔEt(BH+) is the SCIPCM solvation energy for the conjugate Acid, and ΔEt(B) is the solvation energy for the base. A fit to experimental values of ΔH(B) for 10 neutral bases (H2O, MeOH, Me2O, H2S, MeSH, Me2S, NH3, MeNH2, Me2NH, and PH3) gives β=238.4±2.9 kcal/mol when ΔΔEt is computed using the 0.0004 e⋅bohr−3 isodensity surface for defining the solute cavity at the RHF/6–31G** level. The model predicts that for carbon monoxide ΔH(CO)=10 kcal/mol. Thus, protonation of CO is endothermic, and the conjugate Acid HCO+ (formyl cation) behaves as a strong Acid in Fluorosulfonic Acid. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 250–257, 1998
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protonation enthalpies in Fluorosulfonic Acid using ab initio self consistent reaction field theory
Journal of Computational Chemistry, 1998Co-Authors: Tomohiko Ohwada, Koop Lammertsma, Nathan J HarrisAbstract:Electrostatic solvation free energies were computed for several small neutral bases and their conjugate Acids using a continuum solvation model called the self-consistent isodensity polarizable continuum model (SCIPCM). The solvation energies were computed at the restricted Hartree–Fock (RHF) and second-order Moller–Plesset (MP2) levels of theory, as well as with the Becke3–Lee–Yang–Parr (B3LYP) density functional theory, using the standard 6–31G** Gaussian basis set. The RHF solvation energies are similar to those computed at the correlated MP2 and B3LYP theoretical levels. A model for computing protonation enthalpies for neutral bases in Fluorosulfonic Acid solvent leads to the equation ΔH(B)=−PA(B)+ΔEt(BH+)−ΔEt(B)+β, where PA(B) is the gas phase proton affinity for base B, ΔEt(BH+) is the SCIPCM solvation energy for the conjugate Acid, and ΔEt(B) is the solvation energy for the base. A fit to experimental values of ΔH(B) for 10 neutral bases (H2O, MeOH, Me2O, H2S, MeSH, Me2S, NH3, MeNH2, Me2NH, and PH3) gives β=238.4±2.9 kcal/mol when ΔΔEt is computed using the 0.0004 e⋅bohr−3 isodensity surface for defining the solute cavity at the RHF/6–31G** level. The model predicts that for carbon monoxide ΔH(CO)=10 kcal/mol. Thus, protonation of CO is endothermic, and the conjugate Acid HCO+ (formyl cation) behaves as a strong Acid in Fluorosulfonic Acid. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 250–257, 1998
Ali Jabbari - One of the best experts on this subject based on the ideXlab platform.
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A strategy to enhance the thermal stability of a nanostructured polypyrrole-based coating for solid phase microextraction
Microchimica Acta, 2012Co-Authors: Ali Mehdinia, Farzane Bashour, Fateme Roohi, Ali JabbariAbstract:We report on a nanostructured self-doped polypyrrole (SPPy) film that was prepared by an electrochemical technique in an electrolyte containing Fluorosulfonic Acid as the sulfonation reagent. The film was applied as a new fiber material for solid-phase microextraction (SPME) of the pesticides lindane, heptachlor, aldrin, endosulfans I and II prior to their quantitation by GC with electron capture detection. The SPPy nanoparticles have a diameter of
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A strategy to enhance the thermal stability of a nanostructured polypyrrole-based coating for solid phase microextraction
Mikrochimica Acta, 2012Co-Authors: Ali Mehdinia, Farzane Bashour, Fateme Roohi, Ali JabbariAbstract:We report on a nanostructured self-doped polypyrrole (SPPy) film that was prepared by an electrochemical technique in an electrolyte containing Fluorosulfonic Acid as the sulfonation reagent. The film was applied as a new fiber material for solid-phase microextraction (SPME) of the pesticides lindane, heptachlor, aldrin, endosulfans I and II prior to their quantitation by GC with electron capture detection. The SPPy nanoparticles have a diameter of 0.998. The detection limits are
Veaceslav Kulciţki - One of the best experts on this subject based on the ideXlab platform.
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Selectivity Control in Terpene Rearrangements: A Biomimetic Synthesis of the Halimanic Bicyclic Core
Synthesis, 2019Co-Authors: Tatiana Sîrbu, Nicon Ungur, Vladilena Gîrbu, Petru Harghel, Vasile Rusu, Veaceslav KulciţkiAbstract:The bicyclic core of the halimanic framework is synthesized in optically active form by an Acid-induced rearrangement of a homodrimanic epoxide. The substrate can follow two different pathways under Acidic treatment. Using Fluorosulfonic Acid as a promoter at low temperature favors ring contraction to a perhydrindanic structure. In contrast, milder Acids at higher temperatures bring about predominantly an angular methyl migration and formation of the halimanic bicyclic system. In particular, an Acidic pillared clay selectively promoted this transformation.
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ON THE PECULIARITIES OF THE RING CONTRACTION REACTIONS OF HOMODRIMANES VIA Acid MEDIATED EPOXIDE REARRANGEMENT
Institute of Chemistry of ASM, 2011Co-Authors: Veaceslav Kulciţki, Tatiana Sîrbu, Nicon UngurAbstract:A selective rearrangement of a epoxy-homodrimanic substrate is described. Using Fluorosulfonic Acid at low temperature leads by ring contraction to a perhydrindanic structure. On the contrary, using boron trifluoride-diethyl ether at r.t. selectively brings about angular methyl migration
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Further Synthetic Studies Towards the Austrodorane Skeleton: Synthesis of Austrodoral
European Journal of Organic Chemistry, 2005Co-Authors: Veaceslav Kulciţki, Nicon Ungur, Margherita Gavagnin, Marianna Carbone, Guido CiminoAbstract:The synthesis of austrodoral (1), a marine nor-sesquiterpene that contains a unique bicyclic skeleton, has been achieved. The synthetic strategy is based on the ring contraction of a suitable optically active drimanic epoxy derivative, obtained from commercially available (+)-sclareolide (4). Fluorosulfonic Acid was found to promote the ring contraction efficiently. The nor-sesquiterpene hydrocarbon 13, a key intermediate in the synthesis of sesquiterpene hydroquinones, has also been prepared in optically active form. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)