Substituent effects on the electronic structure and pKa of benzoic acid

Hollingsworth, Chad A.; Seybold, Paul G.; Hadad, Christopher M.

doi:10.1002/qua.10362

Cited by 149 publications

(144 citation statements)

References 17 publications

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“…Charges on the ionized oxygen (O -) and the charge on the whole corresponding conjugate anion, (AsO(OH)O -), were also determined and are shown in Table 3. 21,[57][58] Good correlation between calculated pKa and the APT charges can be observed. Table 3.…”

Section: Atomic Chargesmentioning

confidence: 75%

Theoretical calculations of the relative pKa values of some selected aromatic arsonic acids in water using density functional theory

Khalili¹,

Rimaz²

2016

10.5267/j.ccl

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With the focus on calculating the equilibrium constant (Ka) of arsonic acids (RAsO(OH)2) in aqueous media, the behavior of both neutral and negatively charged species of some arsonic acids have been considered through the isodesmic reaction scheme with polarized continuum model of solvation. The relative pKa values of a number of arsonic acids were calculated using density functional theory (DFT), with methylarsonic acid (CH3AsO(OH)2) used as a reference molecule. Various basis sets such as (6-31G(d), 6-31+G(d), 6-311++G(d,p) and 6-311++G(2d,2p)) in conjunction with B3LYP computational method were examined. Finally the latter one was found to give better results. The results of applied B3LYP 6-311++G(2d,2p) method for pKa values of 25 arsonic acids in aqueous media showed good agreement with corresponding experimental pKa values. In this level of theory the average error was less than 0.3 pKa units. The type of substituent affected the acid strength, with electron withdrawing substituents lowering the pKa and electron releasing groups increasing it.

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Section: Atomic Chargesmentioning

confidence: 75%

Theoretical calculations of the relative pKa values of some selected aromatic arsonic acids in water using density functional theory

Khalili¹,

Rimaz²

2016

10.5267/j.ccl

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“…[29] However, a recent study showed that natural population analysis (NPA) charges on carboxylate groups had the strongest correlation with the corresponding pK a values in a series of para-functionalised aromatic carboxylic acids. [33] To gain more insight into the influence of the substituent on the properties of the metal centre, several para-substituted NCN-pincer platinum(ii) chloride complexes [PtCl(NCN-Z)] were investigated by the DFT method B3LYP/LANL2DZ [34] and natural bond order population analysis as implemented in Gaussian 98. [35] Of specific interest in our calculations was the influence of the para substituent on the calculated charges of the platinum centres and the calculated structural features in comparison with single-crystal X-ray structures.…”

mentioning

confidence: 99%

Synthesis and Properties of para‐Substituted NCN‐Pincer Palladium and Platinum Complexes

Slagt

Rodríguez

Grutters

et al. 2004

Chemistry A European J

109

112

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A variety of para-substituted NCN-pincer palladium(II) and platinum(II) complexes [MX(NCN-Z)] (M=Pd(II), Pt(II); X=Cl, Br, I; NCN-Z=[2,6-(CH(2)NMe(2))(2)C(6)H(2)-4-Z](-); Z=NO(2), COOH, SO(3)H, PO(OEt)(2), PO(OH)(OEt), PO(OH)(2), CH(2)OH, SMe, NH(2)) were synthesised by routes involving substitution reactions, either prior to or, notably, after metalation of the ligand. The solubility of the pincer complexes is dominated by the nature of the para substituent Z, which renders several complexes water-soluble. The influence of the para substituent on the electronic properties of the metal centre was studied by (195)Pt NMR spectroscopy and DFT calculations. Both the (195)Pt chemical shift and the calculated natural population charge on platinum correlate linearly with the sigma(p) Hammett substituent constants, and thus the electronic properties of predesigned pincer complexes can be predicted. The sigma(p) value for the para-PtI group itself was determined to be -1.18 in methanol and -0.72 in water/methanol (1/1). Complexes substituted with protic functional groups (CH(2)OH, COOH) exist as dimers in the solid state due to intermolecular hydrogen-bonding interactions.

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“…The calculated energy variables were theoretically calculated using the three methods, and at the five thermal degrees of all imines, which represent the stability of molecules through interference and spatial changes (HOMO, LUMO, hardness, chemical electron voltage, and electrolyte guide). In the literature (Chipman, 2002;Ebead et al, 2010) (Hollingeworth et al, 2002). These variables represent the center of the interaction for the ionization constants.…”

Section: Resultsmentioning

confidence: 99%

Statistical Study of Ionization for a Number of Oximes and Schiff Bases Theoretically by Using Molecular Modeling Programs

M.M.H.Al-Niemi¹,

AL-Shoraify²

2017

Int. J. Curr. Res. Biosci. Plant Biol.

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A b s t r a c t A r t i c l e I n f oIn this study, the study included the calculation of fourteen ionic and aromatic compounds, which included eight oximes and six Schiff bases. The parameters of the ionization of the compounds under study were calculated at absolute temperature (293K) using molecular modeling programs. Methods that included semi-empirical calculations were AUSTEN MOMEL 1 (AM1), Hatree Fock (HF), and Density functional theory (DFT). The polarizable conductor calculation model (CPCM) was used to calculate the physical variables in the solution phase instead of the gas phase using ethanol as a solvent. The ionization constants were calculated using multiple Linear regression (MLR) analysis and using various descriptive variables selected to test their representatively of the observed variation in pK a values These variables include a Mullikan charge on the atoms of the hydroxyl and azomethine group (C = N), the length of the double bond, the angles values, the value of the fixed dipole moment, DIHADRAL, the total energy and the heat of the formation temperature), molecular properties such as HOMO, LUMO, Molecular hardness, electrolyte guide and chemical potential. These values were correlated with pKa values. In this relationship, the values of pK a were calculated theoretically. The results obtained showed that the HF method and the AM1 method were preferable to the EDP method, although all methods were able to complete this type of calculation And with a good efficiency in describing the effect of substituents on pK a values, these results were clearly indicated by the high correlation coefficients (R 2 ) obtained from the regression analysis and the correlation between the practical values of pKa and those calculated theoretically.

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Substituent effects on the electronic structure and pK_a of benzoic acid

Cited by 149 publications

References 17 publications

Theoretical calculations of the relative pKa values of some selected aromatic arsonic acids in water using density functional theory

Theoretical calculations of the relative pKa values of some selected aromatic arsonic acids in water using density functional theory

Synthesis and Properties of para‐Substituted NCN‐Pincer Palladium and Platinum Complexes

Statistical Study of Ionization for a Number of Oximes and Schiff Bases Theoretically by Using Molecular Modeling Programs

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