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The carbonyl infrared stretching frequencies for 57 meta-, para- and ortho-substituted phenyl benzoates, C6H5CO2C6H4-X and alkylbenzoates, C6H5CO2R, containing besides neutral substituents the charged substituents in phenoxy and alkoxy part in dimethyl sulfoxide (DMSO) have been recorded. The carbonyl stretching frequencies, νCO, for meta- and para-substituted phenyl esters of benzoic acids in the case of neutral substituents were found to correlate well with the substituent constants, σ°. The νCO values for ortho derivatives correlated with the inductive substituent constants, σI, only. The values of constants for charged substituents, σ°±, calculated on the basis of the νCO and the 13C NMR chemical shifts, δCO, in DMSO agree well with the σ°± values for the corresponding ion pairs reported by Hoefnagel and Wepster and those determined from the log k values of the alkaline in 4.4 M NaCl solution at 50 °C. Thus, the values of substituent constants for ion pairs of charged substituents estimated on the basis of aqueous data could be successfully used in non-aqueous solution (DMSO) simultaneously with neutral substituents in case the charged substituents were not completely ionized and are in ion pair form. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The second-order rate constants k (dm3mol−1s−1) for alkaline hydrolysis of meta-, para- and ortho-substituted phenyl esters of benzoic acid, C6H5CO2C6H4-X, in aqueous 50.9% (v/v) acetonitrile have been measured spectrophotometrically at 25 °C. In substituted phenyl benzoates, C6H5CO2C6H4-X, the substituent effects log kX − log kH in aqueous 50.9% acetonitrile at 25 °C for para, meta and ortho derivatives showed good correlations with the Taft and Charton equations, respectively. Using the log k values for various media at 25 °C, the variation of the ortho substituent effect with solvent was found to be precisely described with the following equation: Δlog kortho = log kortho − log kH = 1.57σI + 0.93σ°R + 1.08 EsB − 0.030Δ EσI − 0.069Δ Eσ°R, where Δ E is the solvent electrophilicity, Δ E = ES − EH20, characterizing the hydrogen-bond donating power of the solvent. We found that the experimental log k values for ortho-, para- and meta-substituted phenyl benzoates in aqueous 50.9% acetonitrile at 25 °C, determined in the present work, precisely coincided with the log k values predicted with the equation (log kX)calc = (log kHAN)exp + (Δlog kX)calc where the substituent effect (Δlog kX)calc was calculated from equation describing the variation of the substituent effect with the solvent electrophilicity parameter, using for aqueous 50.9% CH3CN the solvent electrophilicity parameter, Δ E = −5.84. In going from water to aqueous 50.9% CH3CN, the ortho inductive term grows twice less as compared with the para polar effect. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

17O NMR spectra for 35 ortho-, para-, and meta-substituted phenyl tosylates (phenyl 4-methylbenzenesulfonates), 4-CH3-C6H4SO2OC6H4-X, at natural abundance in acetonitrile at 50 °C were recorded. The 17O NMR chemical shifts, δ(17O), of the sulfonyl (SO2) and the single-bonded phenoxy (OPh) oxygens for para and meta derivatives correlated well with dual substituent parameter treatment using the Taft inductive, σI, and resonance, σºR, constants. The influence of ortho substituents on the sulfonyl oxygen and the single-bonded phenoxy oxygen chemical shifts, δ(17O), was found to be nicely described by the Charton equation: δ(17O)ortho = δ(17O)H + ρI σI + ρR σ°R + δEsB when the data treatment was performed separately for electron-donating + R substituents and electron-attracting − R substituents. Electron-attracting meta and para substituents in the phenyl moiety caused deshielding while the electron-donating meta, para and ortho + R substituents produce shielding effects on the sulfonyl (SO2) and single-bonded phenoxy (OPh) oxygens. The influence of ortho inductive and resonance effects in the case of + R substituents was found to be approximately twice higher than the corresponding influence from the para position. Due to the steric effect of ortho substituents a decrease in shielding of the oxygens at the sulfonyl group ( δEsB > 0, EsB < 0) was detected. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

17O NMR spectra for 29 phenyl esters of ortho‐, para,‐ and meta‐substituted benzoic acids, X‐C6H4CO2C6H5, at natural abundance in acetonitrile were recorded. The δ(17O) values of carbonyl and the single‐bonded oxygens for para derivatives gave good correlation with the σ+ constants. The δ(17O) values for meta derivatives correlated well with the σm constants. The influence of ortho substituents on the δ(17O) values of carbonyl oxygen and the single‐bonded oxygens was analyzed using the Charton equation containing the inductive, σI, resonance, σ+R, and steric, E sB, substituent constants. For ortho derivatives, excellent correlations with the Charton equation were obtained when the data treatment was performed separately for derivatives containing electron‐donating +R and electron‐attracting −R substituents. The electron‐donating substituents in ortho‐, meta‐, and para‐substituted esters resulted in shielding of the 17O signal and the electron‐withdrawing groups caused deshielding. In phenyl ortho‐substituted benzoates, the substituent‐induced positive inductive (ρI > 0), resonance (ρR > 0), and steric (δorthoE sB > 0) effects were found. The steric interaction of ortho substituents with ester group was found to produce a deshielding effect on the carbonyl and single‐bonded oxygens. For ortho derivatives with −R substituents, the resonance term was insignificant and the steric term was ca. twice weaker as compared to that for derivatives with +R substituents. The δ(17O) values for ortho‐substituted nitrobenzenes, acetophenones, and benzoyl chlorides showed a good correlation with the Charton equation as well. In ortho‐substituted nitrobenzenes the inductive, resonance and steric effect were found to be ca. 1.7 times stronger as compared to that for phenyl ortho‐substituted benzoates. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The second-order rate constants k (dm3 mol-1 s-1) for the alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids in aqueous 5.3 M NaClO4 and 1.0 M Bu4NBr were measured by UV/Vis spectrophotometry at 25 °C. The variations in the ortho inductive, ortho resonance, as well as meta and para polar effects with solvent parameters were studied using data for the alkaline hydrolysis of phenyl esters of substituted benzoic acids in various media. The dependence of the ortho substituent effect on solvent can be precisely described with the following equation: Δlog kortho = log kortho - log kH = 0.059 + 2.19σI + 0.304σ°R + 2.79EsB - 0.016ΔEσI - 0.085ΔEσ°R, where ΔE is the solvent electrophilicity, ΔE = ES - EH2O, characterizing the hydrogen-bond donating power of the solvent. The increase in the meta and para polar substituent effects with decrease in the solvent hydrogen-bond donor capacity (electrophilicity) was approximately to the same extent (-0.068ΔEσ°m,p) as the resonance term for the ortho substituents. The steric term of ortho substituents was independent of the solvent parameters. The variations in the ortho inductive, ortho resonance, as well as meta and para polar substituent effects with the solvent electrophilicity were to the same extent as in phenyl benzoates containing the substituents in the phenyl part. The substituent effects in the alkaline hydrolysis of ethyl benzoates appeared to vary with the solvent electrophilicity nearly to the same extent as in the alkaline hydrolysis of substituted phenyl esters of benzoic acids. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

13C NMR spectra of 37 ortho-, meta-, and para-substituted phenyl benzoates, containing substituents in benzoyl and phenyl moiety, 4 ortho-substituted methyl and 5 ethyl benzoates as well as 9 R-substituted alkyl benzoates have been recorded. The influence of the ortho substituents on the carbonyl carbon 13C NMR chemical shift, δCO, was found to be described by a linear multiple regression equation containing the inductive, σI, resonance, σ°R, and steric, EsB, or υ substituent constants. For all the ortho-substituted esters containing substituents in the acyl part as well as the phenyl part, the substituent-induced reverse inductive effect (ρI < 0), the normal resonance effect (ρR > 0), and the negative steric effect (δortho < 0) with the EsB were observed. In the case of ortho substituents in the phenyl part, the resonance effect was negligible. Due to inductive effect, the ortho electron-withdrawing substituents showed an upfield shift or shielding of the carbonyl carbon, while the electron-donating substituents had an opposite effect. Because of the sterical consequences, ortho substituents revealed a deshielding effect on the 13C NMR chemical shift of the carbonyl carbon. For all the meta- and para-substituted esters, the reverse substituent-induced inductive and resonance effects (ρI < 0, ρR < 0) were found to be significant. In alkyl benzoates, the alkyl substituents showed the reverse inductive and steric effects. The log k values for the alkaline hydrolysis in water, aqueous 0.5 M Bu4NBr and 2.25 M Bu4NBr, and the IR frequencies, νCO, for the ortho-, meta-, and para-substituted phenyl benzoates and alkyl benzoates were correlated nicely with the corresponding 13C NMR substituent chemical shifts, ΔδCO. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The second-order rate constants k for the alkaline hydrolysis of eight substituted alkyl benzoates have been measured spectrophotometrically in aqueous 5.3 M NaClO4 and 0.5 M n-Bu4NBr at various temperatures. Variation of the substituent effect with temperature in alkaline hydrolysis of ortho-, meta-, and para-substituted phenyl benzoates, phenyl tosylates, and alkyl benzoates in various solvents (water, aqueous 0.5 M Bu4NBr, 80% (v/v) DMSO, 2.25 M Bu4NBr, and 5.3 M NaClO4) was studied. The susceptibility to temperature variation of the meta and para polar substituent effect, the ortho inductive effect, and the alkyl polar effect for various media showed good correlation with the solvent electrophilicity, ES, which characterizes the hydrogen-bond donating power of the solvent. The variation of the temperature-dependent ortho inductive effect with solvent hydrogen-bond donor capacity (electrophilicity) was found to be nearly twice smaller than that for meta and para polar effect. The temperature-dependent alkyl polar substituent effect was found to vary with ES nearly by the same extent as the polar effect of meta and para substituents. The dependences of the ρ values (altogether 109 values of ρ) on the (1/T) term for various media were found to cross nearly at the same isosolvent temperature (1/βisosolv ≈ 2 × 10-3) for meta-, para-, ortho-, and alkyl-substituted esters. At T = βisosolv the difference (ρ)S - (ρ)Water becomes zero for all polar substituent effects in all media considered and the additional inductive effect from the ortho position (compared with para derivatives) disappears for all solvents studied. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Infrared spectra of 25 substituted phenyl esters of benzoic acid C6H5CO2C6H4-X (X&dbond;H, 3-Cl, 3-F, 3-CN, 3-NO2, 3-CH3, 3-OH, 3-NH2, 4-Cl, 4-F, 4-NO2, 4-CN, 4-OCH3, 4-CH3, 4-NH2, 2-Cl, 2-F, 2-I, 2-NO2, 2-CF3, 2-CN, 2-CH3, 2-OCH3, 2-N(CH3)2, 2-C(CH3)3), 8 alkyl benzoates C6H5CO2R (X&dbond;CH3, CH2CH3, CH2Cl, CH2CN, CH2C&dbond;CH, CH2CH2Cl, CH2CH2OCH3, CH2C6H5), and 22 phenyl esters of substituted benzoic acids X-C6H4CO2C6H5 (X&dbond;3-Cl, 3-NO2, 3-CH3, 3-N(CH3)2, 4-F, 4-Cl, 4-Br, 4-NO2, 4-CH3, 4-C(CH3)3, 4-OCH3, 4-NH2, 2-Cl, 2-F, 2-Br, 2-I, 2-NO2, 2-CN, 2-CF3, 2-CH3, 2-OCH3, 2-NH2) were recorded in tetrachloromethane in the region of 400–4000 cm-1. Carbonyl stretching frequencies νCO for meta- and para-substituted phenyl esters of benzoic acid and phenyl esters of meta-substituted benzoic acids were shown to correlate with the substituent constants σo. The influence of the through resonance effect on νCO was found to be important in the case of +Rpara substituents in the benzoyl part of phenyl benzoates as well. The carbonyl stretching frequencies of ortho derivatives in phenoxy part were shown to correlate with the inductive substituent constant σI only. In the benzoyl part of the esters the carbonyl stretching frequencies of cis and trans conformers (relative to the carbonyl group) of ortho derivatives were nicely described by dual parameter equations: (νCO)cis = (νCO)o + c1σI + c3 $E_{\rm s}^{\rm B} $and (νCO)trans = (νCO)o + c1σp+ + c3 $E_{\rm s}^{\rm B} $ (R = 0.99). The trans isomers of phenyl esters of ortho-substituted benzoic acids showed direct resonance similar to that for para derivatives. The positive steric term found for both the cis and trans conformers could be considered as measure of the steric inhibition of resonance between the phenyl ring and the carboxy-group caused by bulky ortho substituents. The existence of cis/trans conformations was supported by frequency calculations with Density Functional Theory (DFT) method at B3LYP/6-311+G** level for the ortho-substituted benzoates. In the case of alkyl benzoates good correlations of νCO values were obtained when both the Taft σ* and the steric $E_{\rm s}^{\rm B} $ constants were used. For meta- and para-substituted phenyl benzoates s-trans conformation where the plane of the benzene ring in the benzoyl part of the ester is coplanar with the carbonyl bond plane and the plane of the benzene ring in the phenoxy part is twisted nearly perpendicular relative to the carbonyl bond plane was supported. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The second-order rate constants k2 (M-1 s-1) for the alkaline hydrolysis of meta-, para- and ortho-substituted phenyl benzoates, C6H5CO2C6H4X, in aqueous 0.5 Mn-Bu4NBr were measured spectrophotometrically. The dependence of substituent effects, especially ortho inductive, resonance and steric terms on different solvent parameters, was studied using the following equation: $$\matrix{\Delta\, \log \, k_{ortho}=& c_0 + c_{1(ortho)} \sigma_{\rm I} + c_{2(ortho)} \sigma _{\rm R}^0 + c_{3(ortho)} E_{\rm s}^{\rm B} + c_4 \Delta E + c_5 \Delta Y + c_6 \Delta P + c_{7(ortho)} \Delta E\sigma _{\rm I}\hfill\cr &+c_{8(ortho)} \Delta Y\sigma_{\rm I} + c_{9(ortho)} \Delta P\sigma _{\rm I} + c_{10(ortho)} \Delta E\sigma _{\rm R}^0 + c_{11(ortho)} \Delta Y\sigma _{\rm R}^0 + c_{12(ortho)} \Delta P\sigma _{\rm R}^0\cr}$$ where Δlog k=log kX-log kH, σI, σR0 and EsB are the inductive, resonance and steric substituent constants and E, Y and P are the solvent electrophilicity, polarity and polarizability parameters, respectively. In data treatment $\Delta E = E_{\rm S} - E_{{\rm H}_2 {\rm O}}, \ \Delta Y = Y_{\rm S} - Y_{{\rm H}_2 {\rm O}} \ {\rm and} \ \Delta P = P_{\rm S} - P_{{\rm H}_2 {\rm O}}$ were used. The solvent electrophilicity was found to be the main factor responsible for changes in the ortho, para and meta polar substituent effects with medium. The variation of the ortho inductive term with the solvent electrophilicity ES was found to be ca threefold smaller than that for para substituents, whereas the ortho resonance term appeared to vary with solvent very similarly to that for para substituents. The steric term of ortho substituents was found to be approximately independent of solvent parameters. The ortho effect caused by the supplementary inductive effect from ortho position was found to disappear in a solvent whose electrophilic solvating power is comparable to that of 60% aqueous ethanol (E ≈ 13.3). Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The 17O nuclear magnetic resonance chemical shifts for 31 ortho‐substituted, para‐substituted, and meta‐substituted phenyl esters of 4‐methylbenzenesulfonic acid (phenyl tosylates, 4‐CH3‐C6H4SO2OC6H4‐X) with the neutral and charged substituents in phenoxy part were measured in DMSO‐d6 at 50°C. The chemical shifts, δ(17O), of the sulfonyl (SO2) and single‐bonded phenoxy (O─Ph) oxygens for para and meta derivatives in the case of neutral substituents showed a good correlation with the Taft σI and σ°R substituent constants. The influence of the ortho substituents on the δ(17O) chemical shifts of the sulfonyl oxygens and single‐bonded phenoxy oxygens was found to be described well with the Charton equation: δ(17O)ortho = δ(17O)H + ρIσI + ρRσ°R + δEBs when the data treatment was performed separately for electron‐donating +R substituents and electron‐withdrawing −R substituents. The substituent constants, σ°X±, for the charged substituents (4‐N+(CH3)3I−, 3‐N+(CH3)3I−, 2‐N+(CH3)3I−, 4‐COO−N+Bu4, 3‐COO−N+Bu4, 2‐COO−N+Bu4) calculated from the δ(17O) chemical shifts for phenyl tosylates in DMSO prove that in DMSO, the compounds involving charged substituents are predominantly in ion pair form and not dissociated into free ions. The same conclusion was drawn recently from the carbonyl IR stretching frequencies, νCO, and the carbonyl carbon 13C chemical shifts for substituted phenyl benzoates, C6H5CO2C6H4‐X, in DMSO. It was shown that for ion pairs of the charged substituents in DMSO and concentrated aqueous salt solution, the same substituent constant, σ°X±, could be used. Influence of charged and electroneutral ortho, meta, and para substituents on 17O nuclear magnetic resonance chemical shifts of substituted phenyl tosylates in DMSO was studied. [ABSTRACT FROM AUTHOR]