Kinetics and reactivity of substituted anilines with 2‐chloro‐5‐nitropyridine in dimethyl sulfoxide and dimethyl formamide

El‐Bardan, Ali A.; El-Hegazy, Fatma El-Zahraa M.; Hamed, Ezzat A.

doi:10.1002/kin.10053

Cited by 19 publications

(20 citation statements)

References 31 publications

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“…This information rules out the formation of intermediate 2 as well as intermediates 11 and 12 resulting from the attack of developed carbanion from acetone, Eq. (3), on the ipso carbon or C-4 of the pyridine nucleus respectively [32], while it corroborates the formation of intermediate 3. 1, pathway b).…”

Section: Methodsmentioning

confidence: 60%

Solvent effect on the alkaline hydrolysis of 2‐thiophenyl‐ 3,5‐dinitropyridine

Fathalla¹

2006

Int J of Chemical Kinetics

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The kinetics of the alkaline hydrolysis of 2-thiophenyl-3,5-dinitropyridine were studied spectrophotometrically in different aquo-organic solvents such as methanol, ethanol, npropyl alcohol, iso-propyl alcohol, t-butyl alcohol, acetonitrile, dimethyl sulfoxide, dioxane, and acetone at 30 • C with various solvent compositions up to 80% (v/v) of organic components. An increase in the organic solvent percentage (v/v) has different effects on the reaction rate constants presumably due to hydrogen bond donor HBD and acceptor HBA of the medium and other solvatochromic parameters. Linear and nonlinear plots of log k against the reciprocal of the dielectric constant of the solvent were obtained. The effects are too complex to be analyzed in terms of a single parameter, but an approach using the Kamlet-Taft solvatochromic parameters is applied successfully to six mixed aquo-organic solvent systems. C 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 159-165, 2006

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Section: Methodsmentioning

confidence: 60%

Solvent effect on the alkaline hydrolysis of 2‐thiophenyl‐ 3,5‐dinitropyridine

Fathalla¹

2006

Int J of Chemical Kinetics

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“…[3][4][5][6] The general mechanism for reactions involving amine nucleophiles is shown in Scheme 1, and early studies were concerned with discerning the mechanism of the general basecatalysed step, k B [B]. It is now recognised that in dipolar aprotic solvents, such as dimethyl sulfoxide (DMSO) and acetonitrile, the rate-limiting proton transfer may be from the zwitterionic intermediate Z to base, the RLPT mechanism; or, it may involve general acid catalysis, by BH + , of Scheme 1.…”

Section: Introductionmentioning

confidence: 98%

Effects of ortho‐ and para‐Ring Activation on the Kinetics of S_NAr Reactions of 1‐Chloro‐2‐nitro‐ and 1‐Phenoxy‐2‐nitrobenzenes with Aliphatic Amines in Acetonitrile

et al. 2006

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Rate constants are reported for reaction of 4‐substituted 1‐chloro‐2,6‐dinitrobenzenes 1, 6‐substituted 1‐chloro‐2,4‐dinitrobenzenes 2, and some of the corresponding 1‐phenoxy derivatives, 3 and 4, with n‐butylamine, pyrrolidine and piperidine in acetonitrile as solvent. Values of k1, the rate constant for nucleophilic attack at the 1‐position, increase with increasing ring‐activation but may be reduced by steric repulsion at the reaction centre which increases in the order Cl < OPh, and n‐butylamine < pyrrolidine ≈ piperidine. ortho‐Substituents may also have adverse steric effects, and those of the trifluoromethyl group are particularly serious. X‐ray crystal structures of phenyl 2,4‐dinitro‐6‐trifluoromethylphenyl ether and phenyl 2,6‐dinitro‐4‐trifluoromethylphenyl ether are reported. Base catalysis in the 1‐phenoxy derivatives is attributed to rate‐limiting proton transfer from the zwitterionic intermediates 6 to base. Values of rate constants for this process decrease with increasing steric congestion at the reaction centre and in the order n‐butylamine > pyrrolidine > piperidine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…The enthalpy of activation DH 6 ¼ shows a regular variation on changing the polarity of the para-substituent in the substrate, therefore, the electron -donating substituent p-OMe increases DH 6 ¼ . An additional contribution to the activation parameters from solvation effects is suggested by the observed variations in DS 6 ¼ [26]. The DH 6 ¼ and DS 6 ¼ values in Table 3 were plotted versus the mole fraction of DMSO as shown in Figure 1.…”

Section: Thermodynamic Parameters Of Activationmentioning

confidence: 99%

The Influence of Remote Substituents on the Amine-Catalysed Solvolysis Reaction of Some Para-Substituted Oxazolinones in Water–Dmso Mixtures

Ismail

El‐Sadany

2009

Progress in Reaction Kinetics and Mechanism

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The kinetics of the morpholine-catalysed solvolysis of some p-substituted (Z)-4-benzylidene-2-phenyloxazolin-5-one in water- dimethylsulfoxide mixtures (20-90% V/V) at different temperatures in the range (40-60°C) have been studied. There is an electronic effect in the predicted direction for para-substitution in the benzylidene moiety in different percentage compositions of binary aqueous solvent mixtures. An electron-withdrawing substituent in the benzylidene ring leads to rate enhancement while an electron-donating substituent retarded the rate. A good linear relationship was obtained from plots of log kobs against the σ-Hammett parameter with a positive slope (ρ) at the various experimental temperatures and solvent compositions. Plots of the reaction rate constant ρ against the dielectric constant and the reciprocal temperature gave straight lines. The thermodynamic parameters Δ H≠, Δ S≠ and Δ G≠ have been determined; Δ G≠ increases gradually as the mole fraction of the cosolvent increase, due to a complex quasi-mirror image compensation of Δ H≠ and Δ S≠. A plot of Δ H≠ versus Δ S≠ for the reaction in water–solvent mixtures gave good straight lines with isokinetic temperatures which are higher than the experimental temperature. The higher negative values of the entropy suggest selective solvation by the more polar water molecules.

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Kinetics and reactivity of substituted anilines with 2‐chloro‐5‐nitropyridine in dimethyl sulfoxide and dimethyl formamide

Cited by 19 publications

References 31 publications

Solvent effect on the alkaline hydrolysis of 2‐thiophenyl‐ 3,5‐dinitropyridine

Solvent effect on the alkaline hydrolysis of 2‐thiophenyl‐ 3,5‐dinitropyridine

Effects of ortho‐ and para‐Ring Activation on the Kinetics of S_NAr Reactions of 1‐Chloro‐2‐nitro‐ and 1‐Phenoxy‐2‐nitrobenzenes with Aliphatic Amines in Acetonitrile

The Influence of Remote Substituents on the Amine-Catalysed Solvolysis Reaction of Some Para-Substituted Oxazolinones in Water–Dmso Mixtures

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Kinetics and reactivity of substituted anilines with 2‐chloro‐5‐nitropyridine in dimethyl sulfoxide and dimethyl formamide

Cited by 19 publications

References 31 publications

Solvent effect on the alkaline hydrolysis of 2‐thiophenyl‐ 3,5‐dinitropyridine

Solvent effect on the alkaline hydrolysis of 2‐thiophenyl‐ 3,5‐dinitropyridine

Effects of ortho‐ and para‐Ring Activation on the Kinetics of SNAr Reactions of 1‐Chloro‐2‐nitro‐ and 1‐Phenoxy‐2‐nitrobenzenes with Aliphatic Amines in Acetonitrile

The Influence of Remote Substituents on the Amine-Catalysed Solvolysis Reaction of Some Para-Substituted Oxazolinones in Water–Dmso Mixtures

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Effects of ortho‐ and para‐Ring Activation on the Kinetics of S_NAr Reactions of 1‐Chloro‐2‐nitro‐ and 1‐Phenoxy‐2‐nitrobenzenes with Aliphatic Amines in Acetonitrile