Molecular interaction study of formohydroxamic acid (FHA) with water

Senthilkumar, L.; Kolandaivel, P.

doi:10.1016/j.molstruc.2006.01.020

Cited by 12 publications

(5 citation statements)

References 30 publications

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“…Interestingly, hydroxylamine is the parent compound for the three typical classes of the oxygen‐containing α‐nucleophiles: oximes, amidoximes, and hydroxamic acid . A large number of studies dealing with theoretical and experimental aspects of hydroxamic acid' acidity have been published . Hydroxamic acids exist in different structural isomeric forms and can undergo deprotonation at different sites.…”

Section: Introductionmentioning

confidence: 99%

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

Satnami

Karbhal

Dewangan

2014

Int J of Chemical Kinetics

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The nucleophilic reactivities of hydroxamate (HA−) ions of the structure RCONHO− [R = CH3 (acetohydroxamate, AHA−), C6H5 (benzohydroxamate, BHA−), 2‐OHC6H4 (salicylhydroxamate, SHA−), and 4‐CH3OC6H4 (4‐methoxbenzohydroxamate, MBHA−)] for the hydrolysis of p‐nitrophenyl benzoate (PNPB), tris(3‐nitrophenyl) phosphate (TRIS), and bis(2,4‐dinitrophenyl) phosphate (BDNPP) have been examined kinetically. Over the pH range of 6.7–11.4, the α‐nucleophile (HA−) accelerates deacylation of PNPB and dephosphorylation of TRIS (in cetyltrimethylammonium bromide (CTAB) micelle, 2.0 × 10−3 M). The salicylhydroxamate ion encountered effective catalysis than AHA−, BHA−, and MBHA− ions. The monoanionic SHA− and dianionic SA2− forms of salicylhydroxamic acid are the reactive species. The hydroxamic acid concentration–dependent critical micelle concentration (cmc) and fractional ionization constant (α) and of CTAB provide qualitative information for the micellar incorporation of the hydroxamate ion. The ab initio calculations performed on the hydroxamate ions at restricted Hartree–Fock using the 6‐311G (d,p) basis set revealed the O‐nucleophilicity of hydroxamate ions toward C=O and P=O centers. On the basis of ab initio calculation, it has been concluded that hydroxamic acids can exist into E‐amide and Z‐amide forms. The large stable amide or imide anions of hydroxamate are strong nucleophilic for the esterolytic cleavage of carboxylate and phosphate esters.

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Section: Introductionmentioning

confidence: 99%

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

Satnami

Karbhal

Dewangan

2014

Int J of Chemical Kinetics

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“…17,18 A large number of papers dealing with theoretical and experimental aspects of hydroxamic acids' acidity have been published. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] The complete investigation of the process requires comparison of the results obtained from both experimental measurements and theoretical calculations adapted for reproducing the experimental conditions. Low molecular weight hydroxamic acids have been used as a role model for investigation of larger, naturally produced hydroxamic acids.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the solvent effects are considered in two ways. Since, in ab initio study of the formohydroxamic acid 31 and small aminoacids, 32 the clusters of up to three water molecules were investigated, we also performed calculations for clusters with one and three water molecules. In addition, we extended our investigation to the solute species microsolvated with ten water molecules.…”

Section: Introductionmentioning

confidence: 99%

Acido-Base Behavior of Hydroxamic Acids: Experimental and Ab Initio Studies on Hydroxyureas

et al. 2008

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The values of Ka, DeltaSa, and DeltaHa for deprotonation of hydroxyurea (HU) and N-methylhydroxyurea (NMHU), as targeted compounds, and for betainohydroxamic acid, were potentiometrically determined. Although NMHU has two and HU even three deprotonation sites, the measurements confirm that they behave as weak acids with a single pK a approximately 10. Comparison with analogous thermodynamic parameters previously determined for series of monohydroxamic acids reveals deviations from a DeltaSa, vs DeltaHa plot for HU and NMHU, raising the question of the dissociation site of hydroxureas in water. In addition to the deprotonation of the hydroxyl oxygen, ab initio calculations performed at the MP2/6-311++G(d,p) level of theory for these two compounds indicate a notable participation of the nitrogen deprotonation site in HU. The calculations for the isolated, monohydrate, trihydrate, and decahydrate molecular and anionic forms of hydroxyureas support the importance of hydrogen bonding in the gas and aqueous phases. The hydroxylamino nitrogen in HU is the most acidic site in water, contributing approximately 94% to the overall deprotonation process at 25 degrees C. On the contrary, the hydroxylamino oxygen is by far the most favored deprotonation site in NMHU, contributing almost 100% in aqueous medium. The predicted participations of two deprotonation sites in HU, calculated at the MP2/6-311++G(d,p) level of theory, combined with the calculated relative reaction enthalpy and entropy for the deprotonation, satisfactorily explain the observed deviation from linearity of DeltaHa vs DeltaSa, plot. There is no such a simple explanation for acid-base behavior of NMHU.

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“…Another reason that makes difficult the study of systems bonded by hydrogen bonds is the high computational cost demanded by the use of high-level ab initio formalisms. For this reason, several authors have chosen to use density functional theory (DFT) because of the good results obtained at a considerably lower computational cost. − It is important to mention that even though DFT fails in the description of dispersion forces, hydrogen bonds are mainly of electrostatic character, which is included in DFT …”

Section: Introductionmentioning

confidence: 99%

“…For this reason, several authors have chosen to use density functional theory (DFT) because of the good results obtained at a considerably lower computational cost. [22][23][24][25] It is important to mention that even though DFT fails in the description of dispersion forces, hydrogen bonds are mainly of electrostatic character, which is included in DFT. 26 As a first step toward understanding the behavior of the ethanol-water system, taking into account what has been already published about heterodimers, the purpose of the present research was to study gas phase (ethanol) 2 -water heterotrimers (two ethanol molecules and one water molecule) considering the trans and gauche conformers of ethanol and to analyze the trimerization energies and enthalpies as well as the distance and the bond order of the hydrogen bonds.…”

Section: Introductionmentioning

confidence: 99%

Molecular Interaction of (Ethanol)₂−Water Heterotrimers

et al. 2007

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The potential energy surface of the (ethanol)2-water heterotrimers for the trans and gauche conformers of ethanol was studied using density functional theory. The same approximation was used for characterizing representative clusters of (ethanol)3, (methanol)3, and (methanol)2-water. Trimerization energies and enthalpies as well as the analysis of geometric parameters suggest that the structures with a cyclic pattern in the three hydrogen bonds of the type O-H---O (primary hydrogen bonds), where all molecules are proton donor-acceptor at the same time, are more stable than those with just two primary hydrogen bonds. Additionally, we propose the formation of "secondary hydrogen bonds" between hydrogen atoms of the methyl group of ethanol and the oxygen atom of water or other ethanol molecule (C-H---O), which were found to be weaker than the primary hydrogen bonds.

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Molecular interaction study of formohydroxamic acid (FHA) with water

Cited by 12 publications

References 30 publications

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

Acido-Base Behavior of Hydroxamic Acids: Experimental and Ab Initio Studies on Hydroxyureas

Molecular Interaction of (Ethanol)₂−Water Heterotrimers

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Molecular interaction study of formohydroxamic acid (FHA) with water

Cited by 12 publications

References 30 publications

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

Acido-Base Behavior of Hydroxamic Acids: Experimental and Ab Initio Studies on Hydroxyureas

Molecular Interaction of (Ethanol)2−Water Heterotrimers

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Molecular Interaction of (Ethanol)₂−Water Heterotrimers