Resonance Effect in Hammett Relationship. II. Sigma Constants in Electrophilic Reactions and their Intercorrelation

Yukawa, Yasuhide; Tsuno, Yuho

doi:10.1246/bcsj.32.965

Cited by 192 publications

(63 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the present investigation, rate constants decreased with the introduction of electron‐withdrawing groups and increased with electron‐donating groups into the parent phenol. The reactivity of structurally different phenols (at 313 K) in the present study followed the following trends: TCCA/NaNO 2 ‐triggered nitration : p ‐Me > m ‐Me > o ‐Me > p ‐Cl > o ‐Cl> H > m ‐Cl > p ‐Br > p ‐NO 2 TCCA‐DMF)/NaNO 2 ‐triggered nitration : p ‐Me > o ‐Me > m ‐Me> p ‐Cl > H > o ‐Cl > m ‐Cl > p ‐Br > p ‐NO 2 (TCCA‐DMA)/NaNO 2 ‐triggered nitration : p ‐Me > o ‐Me > p ‐Cl > m ‐Me = o ‐Cl > H > m ‐Cl > p ‐Br > p ‐NO 2 Basically, we tried to cast the obtained data of second‐order rate constants ( k ) into Hammett's structure‐reactivity relationship, but the correlation was not satisfactory in any of the systems studied:

log (k / k_{x}) = ρ σ .

Later, we tried to correlate the data using Hammett's modifications like Yukawa‐Tsuno and Brown‐Okamoto relationships . Rate data were finally interpreted using Charton's multiple linear regression relationship (Charton multiple linear regression analysis) equation as mentioned in Shorter's reviews .…”

Section: Resultssupporting

confidence: 51%

Kinetics and mechanism of trichloroisocyanuric acid/NaNO₂‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions

Muddam

Rajanna

Govardhan

et al. 2019

Int J of Chemical Kinetics

View full text Add to dashboard Cite

Kinetics and mechanism of nitration of aromatic compounds using trichloroisocyanuric acid (TCCA)/NaNO2, TCCA‐N,N‐dimethyl formamide (TCCA‐DMF)/NaNO2, and TCCA‐N,N‐dimethyl acetamide (TCCA‐DMA)/NaNO2 under acid‐free and Vilsmeier‐Haack conditions. Reactions followed second‐order kinetics with a first‐order dependence on [Phenol] and [Nitrating agent] ([TCCA], [(TCCA‐DMF)], or [(TCCA‐DMA)] >> [NaNO2]). Reaction rates accelerated with the introduction of electron‐donating groups and retarded with electron‐withdrawing groups, but did not fit well into the Hammett's theory of linear free energy relationship or its modified forms like Brown‐Okamoto or Yukawa‐Tsuno equations. Rate data were analyzed by Charton's multiple linear regression analysis. Isokinetic temperature (β) values, obtained from Exner's theory for different protocols, are 403.7 K (TCCA‐NaNO2), 365.8 K (TCCA‐DMF)/NaNO2, and 358 K (TCCA‐DMA)/NaNO2. These values are far above the experimental temperature range (303‐323 K), indicating that the enthalpy factors are probably more important in controlling the reaction.

show abstract

log (k / k_{x}) = ρ σ .

Section: Resultssupporting

confidence: 51%

Kinetics and mechanism of trichloroisocyanuric acid/NaNO₂‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions

Muddam

Rajanna

Govardhan

et al. 2019

Int J of Chemical Kinetics

View full text Add to dashboard Cite

show abstract

“…Closer inspection of these deviations implies that the stronger π ‐donor substituent has a larger negative deviation and vice versa. Such a behavior of para π ‐donor substituents has been observed whenever there is difference in the contribution of the resonance effect of π ‐donor substituent between two systems of interest 14–17. Accordingly, these negative deviations in Fig.…”

Section: Resultsmentioning

confidence: 65%

Gas‐phase basicities of acetophenones toward lanthanum cation [La(OMe)]

Than

Badal

Itoh

et al. 2010

J of Physical Organic Chem

View full text Add to dashboard Cite

The relative free energy changes (lanthanum cation basicity, LaCB[L2]) for the reaction [La(OMe)2]L 2+ ⇌ La(OMe) 2+ + 2L were determined in the gas phase for m‐ and p‐substituted acetophenones based on the measurement of ligand exchange equilibria using an FT‐ICR mass spectrometer. The substituent effect on ΔLaCB[L2] of acetophenone is described in terms of the Yukawa–Tsuno equation, ΔG = ρ(σ° + r+ Δ σ R+), with a ρ value of −11.2 and an r+ value of 0.49. From this result, a ρ value of −7.0 and an r+ value of 0.49 were estimated for the monomeric complex [LLa(OMe) 2+] with the aid of theoretical calculations. This ρ value was found to be significantly smaller than that for protonation, and even smaller than Li+ basicity. Such a small ρ value has been attributed to the largely ionic (ion–dipole interaction) nature of the bonding interaction between La(OMe) 2+ and the carbonyl oxygen atom and, in part, to the long distance between La(OMe) 2+ and the substituent. Contrary to the ρ value, the r+ value is identical in both La(OMe) 2+ and Li+ basicities, suggesting that the r+ value of 0.49 can be regarded as a limiting one in a series of Lewis cation basicities of the acetophenone system, H+ (0.86) > Me3Si+ (0.75) > Me3Ge+ (0.71) > Cu+ (0.60) > Li+ = La(OMe) 2+ (0.49). Since the binding interaction between La(OMe) 2+ or Li+ and a neutral ligand is mostly electrostatic, the moderate r+ was interpreted to result from the redistribution of the induced positive charge within the acetophenone moiety upon binding with a metal ion rather than transfer of positive charge from a metal ion to the aromatic moiety. Copyright © 2010 John Wiley & Sons, Ltd.

show abstract

“…Using σ + and σvalues, R + and Rhave also been tabulated [22]. The Swain analysis, which attempts to dissect out substituent effects into their resonance and inductive components, led to the development of the dual-substituent parameter (DSP) approach, represented by the following equation in accordance with the ideas of Yukawa and Tsuno [30,31].…”

Section: A Hammett Constantsmentioning

confidence: 99%

QSAR: Then and Now

Selassie

Mekapati²,

Verma³

2002

CTMC

View full text Add to dashboard Cite

In this review, the evolution of QSAR is traced from the insightful observations of Crum-Brown and Frazier to Hammett's critical equations and finally Hansch's seminal contributions on hydrophobicity and modelling of biological activity based on extrathermodynamic principles. Today's QSAR models can stand alone, augment other graphical approaches or be examined in tandem with equations of a similar mechanistic genre to truly reveal the power of the paradigm. This review will focus on the three standard classifications routinely used in QSAR analysis electronic, hydrophobic, and steric, as well as topological indices. Electronic parameters will focus on Hammett sigma constants and their numerous variations. Dipole moments, hydrogen bond descriptors and quantum chemical indices as well as applications of their utilization will be described. The hydrophobicity parameter will be examined by tracing its early history, its operational definition and its determination by either experimental methods or computational calculations. Steric parameters, which run the gamut from size to shape, will be described by Taft's, Hancock's, Charton's, Fujita's, Verloop's and Simon's contributions. Topological effects, delineated by connectivity indices, kappa shape and electrotopological indices of Kier and Hall are also described. Examples of QSAR models incorporating most of these parameters are reviewed. In cases where the 95% confidence intervals of variables are available, they are listed in parentheses. A brief Comparative QSAR analysis of non-nucleoside reverse transcriptase inhibitors (NNRTI's) is outlined and various models obtained by different groups examining 4, 5, 6, 7-tetrahydro-5-methylimidazo [4, 5,1-j,k][1,4] benzodiazepin-2(1H)-ones (TIBO) and 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)-thymine (HEPT) derivatives are compared for mechanistic insight that could be useful in the process of inhibitor design.

show abstract

Resonance Effect in Hammett Relationship. II. Sigma Constants in Electrophilic Reactions and their Intercorrelation

Cited by 192 publications

References 23 publications

Kinetics and mechanism of trichloroisocyanuric acid/NaNO₂‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions

Kinetics and mechanism of trichloroisocyanuric acid/NaNO₂‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions

Gas‐phase basicities of acetophenones toward lanthanum cation [La(OMe)]

QSAR: Then and Now

Contact Info

Product

Resources

About

Resonance Effect in Hammett Relationship. II. Sigma Constants in Electrophilic Reactions and their Intercorrelation

Cited by 192 publications

References 23 publications

Kinetics and mechanism of trichloroisocyanuric acid/NaNO2‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions

Kinetics and mechanism of trichloroisocyanuric acid/NaNO2‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions

Gas‐phase basicities of acetophenones toward lanthanum cation [La(OMe)]

QSAR: Then and Now

Contact Info

Product

Resources

About

Kinetics and mechanism of trichloroisocyanuric acid/NaNO₂‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions

Kinetics and mechanism of trichloroisocyanuric acid/NaNO₂‐triggered nitration of aromatic compounds under acid‐free and Vilsmeier‐Haack conditions