Solvent Hydrogen Bonding and Structural Effects on Nucleophilic Substitution Reactions: Part 5 – Reaction of 2-Bromo-5-nitropyridine with para-Substituted Anilines in Acetonitrile/Dimethylformamide Mixtures

2008 ◽  
Vol 63 (7-8) ◽  
pp. 493-504 ◽  
Author(s):  
Durvas S. Bhuvaneshwari ◽  
Kuppanagounder P. Elango
Keyword(s):  
Solvent Mixture ◽  
Structural Effects ◽  
Substituted Anilines ◽  
Hydrogen Bond Donor ◽  
Substitution Reactions ◽  
Solvation Model ◽  
Cyclic Voltammetric ◽  
Solvent Interactions ◽  
Multivariate Correlation ◽  
Substituent Constants

Substitution reactions of some para-substituted anilines with 2-bromo-5-nitropyridine are carried out conductometrically in binary acetonitrile/dimethylformamide mixtures. The second-order rate constants correlate well with Hammett’s substituent constants yielding a negative value of ρ. The multiparameter correlation with Kamlet-Taft’s solvatochromic parameters is excellent (100R2 ~ 98%), and the computed percentage contributions of these parameters (Pα = 58%, Pβ = 4%, Pπ∗ = 38%) suggest that both specific and non-specific solute-solvent-solvent interactions influence the reactivity. The solvation model proposed is well supported by the solvatochromism exhibited by the anilines in the solvent mixture under investigation. The molar extinction coefficient (εmax) of aniline varies appreciably up to ~ 25% with a change in the mole fraction of the mixture. The multivariate correlation analysis of εmax (with α, β , π∗) suggests that the solvation around the NH2 moiety of aniline through the solvent’s hydrogen-bond donor (HBD) property is found to be dominant in the solvation process and consequently in altering the rate. The dominance of the solvent’s HBD property in solvation is further confirmed by the cyclic voltammetric oxidation of aniline in the solvent mixture.

Effect of Preferential Solvation on the Kinetics and Thermodynamics of Oxidation of Anilines by Nicotinium Dichromate

2005 ◽  
Vol 60 (10) ◽  
pp. 1105-1111 ◽  
Author(s):  
Durvas S. Bhuvaneshwari ◽  
Kuppanagounder P. Elango
Keyword(s):  
Free Energy ◽  
Preferential Solvation ◽  
Zero Order ◽  
Substituted Anilines ◽  
Isokinetic Relationship ◽  
Solvent Interactions ◽  
Activation Free Energy ◽  
First Order ◽  
Linear Free Energy ◽  
Energy Relationships

The nicotinium dichromate (NDC) oxidation of anilines, in varying mole fractions of benzene/2- methylpropan-2-ol mixtures, in the presence of p-toluenesulfonic acid (TsOH) is first order in NDC and TsOH and zero order with respect to anilines in the concentration range investigated. The NDC oxidation of 15 meta- and para-substituted anilines complies with the isokinetic relationship but not to any of the linear free energy relationships. The activation free energy data failed to correlate with macroscopic solvent parameters such as εr and ENT. Correlation of ΔG# with Kamlet-Taft solvatochromic parameters (α, β , π*) suggests that the specific solute-solvent-solvent interactions play a major role in governing the reactivity.

Effect of para Substitution on Dissociation of N-Phenylbenzenesulfonamides

2004 ◽  
Vol 69 (7) ◽  
pp. 1479-1490 ◽  
Author(s):  
Martin Mansfeld ◽  
Patrik Pařík ◽  
Miroslav Ludwig
Keyword(s):  
Elemental Analysis ◽  
Principal Components ◽  
Latent Variables ◽  
Dissociation Constants ◽  
Additive Model ◽  
Reaction Centre ◽  
Hammett Equation ◽  
Substituted Anilines ◽  
Transmission Effect ◽  
Substituent Constants

The reaction of substituted anilines and benzenesulfonyl chlorides has been used to prepare 49 substituted N-phenylbenzenesulfonamides of general formula 4-X-C6H4SO2NHC6H4-Y-4'. Their purity was checked by elemental analysis. The substituents X and Y include H, CH3, CH3O, Cl, Br, CN, and NO2. The dissociation constants of all compounds were determined by potentiometric titration in methanol, acetonitrile, N,N-dimethylformamide, and pyridine. The obtained dissociation constants, pKHA, were correlated with various sets of substituent constants. It was found that the effects of substituents X and Y on the dissociation are best described by using the Hammett equation with σp constants and the Yukawa-Tsuno equation with σp- and σp constants, respectively. This result confirms the direct conjugation of Y substituent with the reaction centre. The explained variability using the additive model was above 96% in all the solvents used. The data also provided information about the transmission effect of the SO2 group. The average dissociation constants were further processed by the latent variables methods, principal components and conjugated deviations analyses.

scholarly journals Synthesis, structure and solvatochromism of 5-methyl-5-(3-or 4-substituted phenyl)hydantoins

2009 ◽  
Vol 74 (11) ◽  
pp. 1195-1205 ◽  
Author(s):  
Natalija Divjak ◽  
Nebojsa Banjac ◽  
Natasa Valentic ◽  
Gordana Uscumlic
Keyword(s):  
Log P ◽  
Hydrogen Bond Donor ◽  
P Values ◽  
Solvent Interactions ◽  
Effect Of Solvent ◽  
Hydrogen Bonding Interactions ◽  
Chemistry Development ◽  
Donor Solvent ◽  
Hydantoin Derivatives ◽  
Linear Solvation Energy

Several 5-methyl-5-(3- or 4-substituted phenyl)hydantoins were prepared and their ultraviolet absorption spectra were recorded in the region 200-400 nm in twelve solvents of different polarity. The effect of solvent dipolarity/ polarizability and solvent/solute hydrogen bonding interactions were analyzed by means of the linear solvation energy relationship (LSER) concept proposed by Kamlet and Taft. The lipophilic activity of the investigated hydantoins was estimated by calculation of log P values with Advanced Chemistry Development Software. The calculated values of log P were correlated with the contribution of hydrogen bond donor-solvent interactions. By employing the thus obtained linear dependence, the pharmacological activity of the studied hydantoin derivatives is discussed.

Structural Effects on Nitrile Infrared Integrated Intensities of Alpha,Beta-Diaryl Cyanoethylenes: Hammett and Quantum Chemical Approaches

1978 ◽  
Vol 33 (5) ◽  
pp. 557-563 ◽  
Author(s):  
Ivan Juchnovski ◽  
Rositza Kuzmanova ◽  
Jordan Tsenov ◽  
José Kaneti ◽  
Ivan Binev
Keyword(s):  
Steric Hindrance ◽  
Quantum Chemical ◽  
Nitrile Group ◽  
Structural Effects ◽  
Mo Calculations ◽  
Infrared Intensities ◽  
Substituent Constants ◽  
Alpha Beta ◽  
Integrated Intensities ◽  
Derivatives Of

AbstractThe nitrile infrared intensities of a series of a,β-diaryl cyanoethylenes were juxtaposed to the associated substituent constants, HMO and SCF-MO indices and fair to excellent correlations were established. The competitive resonance of the nitrile group with alpha-and beta-aryl substituents is discussed. HMO calculations were used to estimate the steric hindrance to conjugation caused by polycyclic substituents and SCF-MO calculations were made to obtain uniform predictions of nitrile intensities and frequencies for hetero-cyclic derivatives of acrylonitrile.

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