1
|
Um IH, Moon HJ, Shin YH, Dust JM. Medium effect on the α-effect for nucleophilic substitution reactions of p-nitrophenyl acetate with benzohydroxamates and m-chlorophenoxide in DMSO–H2O mixtures as contrasts with MeCN–H2O mixtures: comparing two very different polar aprotic solvent components. CAN J CHEM 2018. [DOI: 10.1139/cjc-2018-0103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A kinetic study is reported on nucleophilic substitution reactions of p-nitrophenyl acetate (1a) with three α-effect nucleophiles, benzohydroxamate (BHA–), p-methylbenzohydroxamate (MBHA–), and p-methyl-N-methylbenzohydroxamate (M2BHA–), and a reference nucleophile, m-chlorophenoxide (m-ClPhO–), in DMSO–H2O mixtures of varying compositions at 25.0 ± 0.1 °C. Second-order rate constants for the reactions with BHA– and MBHA– decrease upon addition of DMSO to the reaction medium up to 60 mol % DMSO and then increase thereafter only a little. In contrast, M2BHA– and m-ClPhO– become much more reactive as the DMSO content in the medium increases. Such contrasting medium effects on reactivity are consistent with the report that hydroxamic acids behave as OH acids in H2O but as NH acids in dipolar aprotic solvents (e.g., DMSO and MeCN). It has been concluded that BHA– and MBHA– form an equilibrium of a reactive form I with less reactive species II in DMSO–H2O mixtures and the position of the equilibrium is dependent on solvent compositions. BHA– and MBHA– exhibit the α-effect in H2O but not in in 90 mol % DMSO. In contrast, the α-effect yielded by M2BHA– increases steeply up to 70 mol % DMSO and then levels off thereafter.
Collapse
Affiliation(s)
- Ik-Hwan Um
- Department of Chemistry, Ewha Womans University, Seoul 03767, Korea
| | - Hyun-Jung Moon
- Department of Chemistry, Ewha Womans University, Seoul 03767, Korea
| | - Young-Hee Shin
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Julian M. Dust
- Departments of Chemistry and Environmental Science, Grenfell Campus-Memorial University of Newfoundland, Corner Brook, NL A2H 5G4, Canada
| |
Collapse
|
2
|
Arora R, Issar U, Kakkar R. Theoretical study of the molecular structure and intramolecular proton transfer in benzohydroxamic acid. COMPUT THEOR CHEM 2017. [DOI: 10.1016/j.comptc.2017.02.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
3
|
Brandès S, Sornosa-Ten A, Rousselin Y, Lagrelette M, Stern C, Moncomble A, Cornard JP, Meyer M. Conformational and structural studies of N-methylacetohydroxamic acid and of its mono- and bis-chelated uranium(VI) complexes. J Inorg Biochem 2015; 151:164-75. [PMID: 26116424 DOI: 10.1016/j.jinorgbio.2015.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 05/29/2015] [Accepted: 06/01/2015] [Indexed: 12/18/2022]
Abstract
The thermodynamics and kinetics of the cis/trans isomerism of N-methylacetohydroxamic acid (NMAH) and its conjugated base (NMA(-)) have been reinvestigated in aqueous media by (1)H NMR spectroscopy. Hindered rotation around the central C-N bond due to electronic delocalization becomes slow enough on the NMR time scale to observe both rotamers in equilibrium in D2O at room temperature. By properly assigning the methyl group resonances, evidence for the prevalence of the E over the Z form is unambiguously provided [K300=[E]/[Z]=2.86(2) and 9.63(5) for NMAH and NMA(-), respectively], closing thereby a long-lasting dispute about the most stable conformer. To that end, calculations of the chemical shifts by density functional theory (DFT), which accurately reproduced the experimental data, turned out to be a much more reliable method than the direct computation of the relative energy for each conformer. The Z ⇌ E interconversion dynamics was probed at 300 K in D2O by 2D exchange-correlated spectroscopy (EXSY), affording the associated rate constants [kZE=9.0(2) s(-1) and kEZ=3.14(5) s(-1) for NMAH, kZE=0.96(3) s(-1) and kEZ=0.10(2) s(-1) for NMA(-)] and activation barriers at 300 K [ΔG(≠)ZE=68.0 kJ mol(-1) and ΔG(≠)EZ=70.6 kJ mol(-1) for NMAH, ΔG(≠)ZE=73.6 kJ mol(-1) and ΔG(≠)EZ=79.2 kJ mol(-1) for NMA(-)]. For the first time, mono- and bis-chelated uranium(VI) complexes of NMA(-) have been isolated. Crystals of [UO2(NMA)(NO3)(H2O)2] and [UO2(NMA)2(H2O)] have been characterized by X-ray diffractometry, infrared and Raman spectroscopies.
Collapse
Affiliation(s)
- Stéphane Brandès
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France
| | - Alejandra Sornosa-Ten
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France
| | - Yoann Rousselin
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France
| | - Mickael Lagrelette
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France
| | - Christine Stern
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France
| | - Aurélien Moncomble
- Laboratoire de Spectrochimie Infrarouge et Raman (LASIR), UMR 8516, CNRS, Université de Lille - Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France
| | - Jean-Paul Cornard
- Laboratoire de Spectrochimie Infrarouge et Raman (LASIR), UMR 8516, CNRS, Université de Lille - Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France
| | - Michel Meyer
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université de Bourgogne Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France.
| |
Collapse
|
4
|
Tolosa S, Mora-Diez N, Hidalgo A, Sansón JA. Amide-imide tautomerism of acetohydroxamic acid in aqueous solution: quantum calculation and SMD simulations. RSC Adv 2014. [DOI: 10.1039/c4ra06124a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The kinetics and the thermodynamics of the amide-imide tautomerizations of acetohydroxamic acid in aqueous solution are studied from a theoretical point of view.
Collapse
Affiliation(s)
- S. Tolosa
- Departamento de Ingeniería Química y Química Física
- Universidad de Extremadura
- Badajoz, Spain
| | - N. Mora-Diez
- Department of Chemistry
- Thompson Rivers University
- Kamloops, Canada
| | - A. Hidalgo
- Departamento de Ingeniería Química y Química Física
- Universidad de Extremadura
- Badajoz, Spain
| | - J. A. Sansón
- Departamento de Ingeniería Química y Química Física
- Universidad de Extremadura
- Badajoz, Spain
| |
Collapse
|
5
|
Tavakol H. Computational study of simple and water-assisted tautomerism of hydroxamic acids. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.theochem.2009.09.032] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
6
|
García B, Secco F, Ibeas S, Muñoz A, Hoyuelos FJ, Leal JM, Senent ML, Venturini M. Structural NMR and ab initio study of salicylhydroxamic and p-hydroxybenzohydroxamic acids: evidence for an extended aggregation. J Org Chem 2007; 72:7832-40. [PMID: 17887699 DOI: 10.1021/jo0709798] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The acid-base behavior and self-aggregation of salicylhydroxamic (SHA) and p-hydroxybenzohydroxamic acids (PHBHA)have been investigated by UV and 1HNMR spectroscopy, respectively. The acid-base parameters, measured in H2O at 25 degrees C and I=0.1 M, were pK1=7.56, pK2=9.85 for SHA and pK1=8.4, pK2=9.4 for PHBHA. The 1H NMR signals for salicylhydroxamic and p-hydroxybenzohydroxamic acids measured in acetone indicate that both acids self-aggregate according to a mechanism where two monomers produce planar E-E dimers stabilized by horizontal H-bonds. Further dimer aggregation yields sandwich-like tetramer structures stabilized by vertical H-bonds and pi-pi interactions. The p-hydroxybenzohydroxamic tetramers, less stable than those of salicylhydroxamic, contain two water molecules in their structures. The gas-phase structures of salicylhydroxamic acid and its anions were investigated by ab initio calculations using the density functional theory at the B3LYP/AUG-cc-pVDZ level. The SHA most stable gas-phase conformer is the A-Z amide, a structure with all three phenolate (OP), carboxylate (OC), and hydroxamate (OH) oxygen atoms in the cis position. The B-Z amide, with the OP oxygen trans to OC, lies 5.4 kcal above the A-Z amide. The most stable monoanion is the N-deprotonated A-Z amide.
Collapse
Affiliation(s)
- Begoña García
- Universidad de Burgos, Departamento de Química, 09001 Burgos, Spain.
| | | | | | | | | | | | | | | |
Collapse
|
7
|
|
8
|
Schraml J, Tkadlecová M, Pataridis S, Soukupová L, Blechta V, Roithová J, Exner O. Ring-substituted benzohydroxamic acids: 1H, 13C and 15N NMR spectra and NH-OH proton exchange. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:535-542. [PMID: 15861383 DOI: 10.1002/mrc.1586] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
NMR spectra (1H, 13C, 15N) of para- and meta-substituted benzohydroxamic acids were studied in dry dimethyl sulfoxide solutions. The 13C chemical shifts were very close to those found by cross-polarization magic angle spinning in solids, the hydroxamic (not hydroximic) structure of which is unambiguous. The hydroxamic structure of these acids in DMSO solutions was proved independently by their 15N chemical shifts. The 15N and 1H chemical shifts of the NH-OH fragment showed excellent mutual dependences and dependences on the nature of the ring substituent. According to these dependences and ab initio energy calculations, all the acids assume the same Z conformation. Proton exchange between hydroxamic OH and NH groups in DMSO proceeded by both intra- and intermolecular exchange and the rates did not exhibit any simple relationship to the substituent constants.
Collapse
Affiliation(s)
- Jan Schraml
- Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 16502 Prague 6, Czech Republic.
| | | | | | | | | | | | | |
Collapse
|
9
|
García B, Ibeas S, Leal JM, Secco F, Venturini M, Senent ML, Niño A, Muñoz C. Conformations, Protonation Sites, and Metal Complexation of Benzohydroxamic Acid. A Theoretical and Experimental Study. Inorg Chem 2005; 44:2908-19. [PMID: 15819578 DOI: 10.1021/ic049438g] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A theoretical and experimental study on the structure and deprotonation of benzohydroxamic acid (BHA) has been performed. Calculations at the RHF/cc-pVDZ level, refined by the B3LYP/AUG-cc-pVDZ method, indicate that, in the gas phase, Z amide is the most stable structure of both neutral and deprotonated BHA. (1)H-(1)H nuclear Overhauser enhancement spectroscopy and (1)H-(1)H correlation spectroscopy spectra in acetone, interpreted with ab initio interatomic distances, reveal that BHA is split into the Z and E forms, the [E]/[Z] ratio being 75:25 at -80 degrees C. The formation of E-E, Z-Z, and E-Z dimers has been detected; in the presence of water, the dimers dissociate to the corresponding monomers. The rates of proton exchange within the Z and E forms and between E and Z were measured by dynamic (1)H NMR in the -60 to 40 degrees C temperature range; an increase in water content lowers the rate of exchange of the E isomer. The effect of D(2)O on the NMR signals indicates a fast hydrogen exchange between D(2)O and the E and Z amide forms. The sequence of the acid strength at low temperatures is (N)H(E)) approximately (O)H(E) < (O)H(Z) approximately (N)H(Z). The kinetics of complex formation between BHA and Ni(2+), investigated by the stopped-flow method, show that both neutral BHA and its anion can bind Ni(2+). Whereas the anion reacts at a "normal" speed, the rate of water replacement from Ni(H(2)O)(6)(2+) by neutral BHA is about 1 order of magnitude less than expected. This behavior was interpreted assuming that, in aqueous solution, BHA mainly adopts a closed (hydrogen-bonded) Z configuration, which should open (with an energy penalty) for the metal binding process to occur.
Collapse
Affiliation(s)
- Begoña García
- Departamento de Química, Universidad de Burgos, 09001 Burgos, Spain.
| | | | | | | | | | | | | | | |
Collapse
|
10
|
The structural study of acetohydroxamic and oxalodihydroxamic acids in DMSO solution based on the DFT calculations of NMR spectra. J Mol Struct 2004. [DOI: 10.1016/j.molstruc.2004.01.067] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
11
|
Senent ML, Niño A, Muñoz Caro C, Ibeas S, García B, Leal JM, Secco F, Venturini M. Deprotonation sites of acetohydroxamic acid isomers. A theoretical and experimental study. J Org Chem 2003; 68:6535-42. [PMID: 12919013 DOI: 10.1021/jo0341564] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Theoretical (ab initio calculations) and experimental (NMR, spectrophotometric, and potentiometric measurements) investigations of the isomers of acetohydroxamic acid (AHA) and their deprotonation processes have been performed. Calculations with the Gaussian 98 package, refined at the MP2(FC)/AUG-cc-pVDZ level considering the molecule isolated, indicate that the Z(cis) amide is the most stable form of the neutral molecule. This species and the less stable (Z)-imide form undergo deprotonation, giving rise to two stable anions. Upon deprotonation, the E(trans) forms give three stable anions. The ab initio calculations were performed in solution as well, regarding water as a continuous dielectric; on the basis of the relative energies of the most stable anion and neutral forms, calculated with MP2/PCM/AUG-cc-pVDZ, N-deprotonation of the amide (Z or E) structure appeared to be the most likely process in solution. NMR measurements provided evidence for the existence of (Z)- and (E)-isomers of both the neutral and anion forms in solution. Comparisons of the dynamic NMR and NOESY (one-dimensional) results obtained for the neutral species and their anions were consistent with N-deprotonation, which occurred preferentially to O-deprotonation. The (microscopic) acid dissociation constants of the two isomers determined at 25 degrees C from the pH dependence of the relevant chemical shifts, pK(E) = 9.01 and pK(Z) = 9.35, were consistent with the spectrophotometric and potentiometric evaluations (pK(HA) = 9.31).
Collapse
Affiliation(s)
- María L Senent
- Departamento de Astrofísica Molecular e Infrarroja, Serrano 113b, Madrid 28006, Spain
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Remko M. The Gas-Phase Acidities of Substituted Hydroxamic and Silahydroxamic Acids: A Comparative ab Initio Study. J Phys Chem A 2002. [DOI: 10.1021/jp020300y] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Milan Remko
- Department of Pharmaceutical Chemistry, Comenius University, Odbojárov 10, SK-832 32 Bratislava, Slovakia
| |
Collapse
|
13
|
Brown DA, Cuffe LP, Fitzpatrick GM, Fitzpatrick NJ, Glass WK, Herlihy KM. Experimental and Theoretical Studies of Rotational Barriers in Aceto-, N-Methylaceto- and N-Phenylacetohydroxamic Acid. ACTA ACUST UNITED AC 2001. [DOI: 10.1135/cccc20010099] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Experimental and theoretical calculations for the E and Z forms of aceto-, N-methylaceto- and N-phenylacetohydroxamic acid are reported. The experimental method was NMR spectroscopy, while the computational methods included Hartree-Fock, Møller-Plesset and density functional theory calculations, with and without solvation, using either the Onsager or Tomasi's PCM method. In all calculations zero point energy corrections were included. The computed results when compared with the experimental ones show that, irrespective of the method used, the differences in the rotational barriers, ∆(E-TS) and ∆(Z-TS), are slight and below the 3 kcal mol-1 limit of the theoretical methods. In general the results using the PCM method were worse than the ones obtained from gas phase calculations or using the Onsager method, even though the PCM method is computationally most expensive. The calculations show, using either the Hartree-Fock or the B3LYP approach, that considering solvation using the Onsager method improves agreement with the experiment results. The calculated barrier heights, excluding the PCM method, agree broadly with the experimental results. Thus using the Onsager approach or gas phase calculations adequate results for barrier heights, but not for relative differences, were obtained.
Collapse
|
14
|
Yen SJ, Lin CY, Ho JJ. Ab Initio Study of Proton Transfer between Protonated Formohydroxamic Acid and Water Molecules. J Phys Chem A 2000. [DOI: 10.1021/jp0021143] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Szu-Jen Yen
- Department of Chemistry, National Taiwan Normal University, 88, Section 4, Tingchow Road, Taipei, Taiwan 117, ROC
| | - Ching-Yeh Lin
- Department of Chemistry, National Taiwan Normal University, 88, Section 4, Tingchow Road, Taipei, Taiwan 117, ROC
| | - Jia-Jen Ho
- Department of Chemistry, National Taiwan Normal University, 88, Section 4, Tingchow Road, Taipei, Taiwan 117, ROC
| |
Collapse
|
15
|
Niño A, Muñoz-Caro C, Senent M. Suitability of different levels of theory for modelling of hydroxamic acids. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0166-1280(00)00342-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
16
|
Structure, reactivity and vibrational spectra of formohydroxamic and silaformohydroxamic acids: a comparative ab initio study. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0166-1280(99)00503-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
17
|
Abstract
This work presents a theoretical study of acetohydroxamic acid and its protonation processes using ab initio methodology at the MP2(FC)/cc-pdVZ level. We find the amide form more stable than the imidic tautomer by less than 1.0 kcal mol(-)(1). For comparison with the experimental data, a three-dimensional conformational study is performed on the most stable tautomer (amide). From this study, the different barriers to rotation and inversion are determined and the intramolecular hydrogen bond between the OH group and the carbonyl oxygen is characterized. The electrostatic potential distribution shows three possible sites for electrophilic attack, but it is shown that only two of them, the carbonyl oxygen and the nitrogen atoms, are actual protonation sites. The protonation energy (proton affinity) is obtained from the results of the neutral and charged species. Proton affinities for the species charged on the carbonyl oxygen and the nitrogen atoms are estimated to be 203.4 and 194.5 kcal mol(-)(1), respectively. The development of a statistical model permits the quantification of DeltaG (gas-phase basicity) for the two protonation processes. In this way, the carbonyl oxygen protonated form is found to be more stable than that of the nitrogen atoms by 8.3 kcal mol(-)(1) at 1 atm and 298.15 K, due to the enthalpic contribution. As temperature increases, the proportion of the nitrogen protonated form increases slightly.
Collapse
|
18
|
El Yazal J, Pang YP. Novel Stable Configurations and Tautomers of the Neutral and Deprotonated Hydroxamic Acids Predicted from High-Level ab Initio Calculations. J Phys Chem A 1999. [DOI: 10.1021/jp992203j] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jamal El Yazal
- Mayo Clinic Cancer Center, Tumor Biology Program, Department of Pharmacology, Mayo Foundation for Medical Education and Research, 200 First Street SW, Rochester, Minnesota 55905
| | - Yuan-Ping Pang
- Mayo Clinic Cancer Center, Tumor Biology Program, Department of Pharmacology, Mayo Foundation for Medical Education and Research, 200 First Street SW, Rochester, Minnesota 55905
| |
Collapse
|
19
|
|