Theoretical study of substituent effects on the gas‐phase stabilities of phenoxide anions

Nakata, Kohei; Fujio, Mizue; Nishimoto, Kichisuke; Tsuno, Yuho

doi:10.1002/poc.2953

Cited by 6 publications

(2 citation statements)

References 46 publications

(48 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Combining these parameters through a Yukawa–Tsuno (or Young–Jencks 82 ) analysis probably provides a better approach to correlating the effect of varying phenolic leaving groups on rates of reaction. Recent work 83 has proposed the introduction of an additional saturation term (for electron-releasing substituents) in an extended Yukawa–Tsuno equation to analyze phenolates, but there are seldom enough data in these reactivity-based LFER to justify the inclusion of a third term. Furthermore, because for slow reactions the phenols chosen tend to be more rather than less acidic than the parent and so these leaving groups feature less heavily than those with strongly electron withdrawing groups, in the data presented here, leaving groups with strongly electron-releasing groups do not feature.…”

Section: Resultsmentioning

confidence: 99%

The Alkaline Hydrolysis of Sulfonate Esters: Challenges in Interpreting Experimental and Theoretical Data

et al. 2013

View full text Add to dashboard Cite

Sulfonate ester hydrolysis has been the subject of recent debate, with experimental evidence interpreted in terms of both stepwise and concerted mechanisms. In particular, a recent study of the alkaline hydrolysis of a series of benzene arylsulfonates (Babtie et al., Org. Biomol. Chem.10, 2012, 8095) presented a nonlinear Brønsted plot, which was explained in terms of a change from a stepwise mechanism involving a pentavalent intermediate for poorer leaving groups to a fully concerted mechanism for good leaving groups and supported by a theoretical study. In the present work, we have performed a detailed computational study of the hydrolysis of these compounds and find no computational evidence for a thermodynamically stable intermediate for any of these compounds. Additionally, we have extended the experimental data to include pyridine-3-yl benzene sulfonate and its N-oxide and N-methylpyridinium derivatives. Inclusion of these compounds converts the Brønsted plot to a moderately scattered but linear correlation and gives a very good Hammett correlation. These data suggest a concerted pathway for this reaction that proceeds via an early transition state with little bond cleavage to the leaving group, highlighting the care that needs to be taken with the interpretation of experimental and especially theoretical data.

show abstract

Section: Resultsmentioning

confidence: 99%

The Alkaline Hydrolysis of Sulfonate Esters: Challenges in Interpreting Experimental and Theoretical Data

et al. 2013

View full text Add to dashboard Cite

show abstract

“…We have reported some applications of eq. 2 previously [8][9][10][11][12]. In the course of our studies, a through-resonance effect was found in 1, although it was slight [12].…”

Section: Introductionmentioning

confidence: 98%

Computational study of the substituent effects on the gas-phase stabilities of phenylboranylmethyl anions

Nakata

Fujio

2017

Pure and Applied Chemistry

Self Cite

View full text Add to dashboard Cite

The relative gas-phase stabilities of ring-substituted phenylboranylmethyl anions were computationally determined using isodesmic reactions. The energies of species included in the reactions were calculated at the B3LYP/6-311+G(2d,p) level of theory. The obtained substituent effects were analyzed by the extended Yukawa-Tsuno equation, and unexpectedly substantial r − (0.59) and s (0.65) values were found for the fully-optimized planar anion. The substantial through-resonance effect quantified by the r − value was observed, although it is not possible to draw a canonical form in which the negative charge is delocalized on the benzene ring. Substituent effects were also analyzed for the anions in which the dihedral angle (φ) between the side chain plane and the benzene ring was fixed. The r − value decreased significantly by changing the φ from 0° to 90°, while the s value changed little. NBO analyses revealed that the r − value is proportional to the sum of the π-π* and σ-π* orbital interactions between the side chain and the benzene ring. This fact shows that the through-resonance effect quantified by the r − value is present at all φ, and therefore, the anion cannot become an ideal σ 0 -reference system. The constant saturation effect quantified by the s value can be explained by the constant charge distributed to the benzene ring. The combination of substituenteffect analysis and NBO analysis successfully revealed the nature of the anion.

show abstract

Theoretical Study of Substituent Effects on the Gas‐Phase Acidities of Benzoic and Phenylacetic Acids

Nakata¹,

Fujio²,

Nishimoto³

et al. 2013

ChemPlusChem

View full text Add to dashboard Cite

The relative gas‐phase acidities of 25 ring‐substituted benzoic and phenylacetic acids were theoretically determined with proton‐transfer reactions. The energies and geometries of the acids and their corresponding anions, which were involved in the reactions, were calculated at the B3LYP/6‐311+G(2d,p) level of theory. The obtained substituent effects were compared with each other and those of phenols. The acidities of the benzoic and phenylacetic acids were governed by three kinds of electronic effects (inductive, resonance, and saturation effects), which confirmed that the acidities were reflected in the nature of the benzoate and phenylacetate anions, respectively. Substituent effect analyses with an extended Yukawa–Tsuno equation, ${ - {\rm{\Delta }}E_X = \rho \left( {\sigma ^0 + r^ - {\rm{\Delta }}\bar \sigma _{\rm{R}}^ - + s{\rm{\Delta }}\bar \sigma _{\rm{S}} } \right)}$, gave excellent linear correlations for both anionic systems. The degrees of through‐resonance and saturation effects in the phenylacetate anion, as reflected by the resultant r− and s values, were unexpectedly larger than those in the benzoate anion, which were mainly attributed to hyperconjugation and through‐space interactions between the anionic moiety and the benzene π‐electron system, respectively. The acidities of the benzoic acids (or stabilities of the benzoate anions) constituted a better system than the acidities of phenylacetic acids (or stabilities of the phenylacetate anions) for a standard of the normal substituent constants (σ0) for anions in the gas phase, in contrast to solution‐phase results.

show abstract

Theoretical study of substituent effects on the gas‐phase stabilities of phenoxide anions

Cited by 6 publications

References 46 publications

The Alkaline Hydrolysis of Sulfonate Esters: Challenges in Interpreting Experimental and Theoretical Data

The Alkaline Hydrolysis of Sulfonate Esters: Challenges in Interpreting Experimental and Theoretical Data

Computational study of the substituent effects on the gas-phase stabilities of phenylboranylmethyl anions

Theoretical Study of Substituent Effects on the Gas‐Phase Acidities of Benzoic and Phenylacetic Acids

Contact Info

Product

Resources

About