• Journal of the Korean Chemical Society
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• v.41 no.1
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• pp.22-46
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• 1997

Kinetic studies on nucleophilic substitution reaction of phenacyl bromide and phenacyl chloride with pyridines were conducted at 25℃ and 35℃ in methanol-acetonitrile solvents mixtures. It was shown that the reaction proceeds via an SN2 reaction mechanism based on the transition state parameters, ΔH≠ and ΔS≠ and Bro nsted β values. Quantum mechanical model predicted a product-like transition state, where bond-formation is much more progressed than bond breaking, upon changing the leaving group to that with a better leaving ability.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1945-1950
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• 2011

The pyridinolysis of methyl phenyl phosphinic chloride is investigated kinetically in acetonitrile at -20.0 $^{\circ}C$. The Hammett and Br${\o}$nsted plots for substituent X variations in the nucleophiles are biphasic concave downwards with a break point at X = H, and unusual positive ${\rho}_X$ (= 2.94) and negative ${\beta}_X$ (= -0.48) values are obtained for the strongly basic nucleophiles. A stepwise mechanism with a rate-limiting step change from bond breaking for the weakly basic pyridines to bond formation for the strongly basic pyridines is proposed on the basis of biphasic concave downward Hammett and Br${\o}$nsted plots. Unusual positive ${\rho}_X$ and negative ${\beta}_X$ values are rationalized by the isokinetic relationship. The pyridinolyses and anilinolyses of four $R_1R_2$P(=O)Cl-type substrates, dimethyl, diethyl, methyl phenyl, and diphenyl phosphinic chlorides in acetonitrile are compared to obtain systematic information on phosphoryl transfer reaction mechanism. The combination of the two ligands, Me and Ph, shows unexpected kinetic results for both the anilinolysis and pyridinolysis: greatest magnitude of $k_H/k_D$ (= 2.10) involving deuterated anilines $[XC_6H_4NH_2(D_2)]$ for the anilinolysis, and exceptionally fast rate and biphasic concave downward free energy correlation for the pyridinolysis.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1873-1878
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• 2011

Under solvent-free conditions and in one-pot, a series of 2-amino-4-aryl-3-cyano-6-(3,4-dimethoxyphenyl)-pyridines and 4-aryl-3-cyano-6-(3,4-dimethoxyphenyl)-2(1H)-pyridinones were prepared using 3,4-dimethoxyacetophenone, an aldehyde, malononitrile (or ethyl cyanoacetate), and ammonium acetate in the presence of 3-methyl-1-(4-sulfonylbutyl)imidazolium hydrogen sulfate $[HO_3S(CH_2)_4MIM][HSO_4]$ (a Br${\o}$nsted acidic ionic liquid) as the catalyst in very short reaction time. The preference for the formation of more stable tautomers was consistence with the theoretical calculation using the Gaussian 03 program at the B3LYP hybrid density functional level.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.48-52
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• 1988

Kinetics of the reaction of 2-phenethyl p-bromobenzenesulfonate with substituted pyridines in acetonitrile were investigated by an electric conductivity method at 1-2000 bars and $45{\sim}55{\circ}C$. The rates of these reactions were increased with raising temperatures, pressures and by changing electron-donating substitutents in pyridine. When raising pressure the Hammett reaction parameter $I{\rho}I$ and Bronsted ${\beta}$ values were increased, and isokinetic temperature observed from isokinetic relations hip between ${\Delta}H^{\neq}$ and TEX>${\Delta}S^{\neq}$ was decreased. These results indicate that the $S_N2$ characters were increased with raising pressure.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.159-165
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• 1986

The effects of substituents, pressure and temperature on the dissociation constants of alkylpyrines(2, 3 and 4-methyl and ethyl) were studied by measuring the dissociation constants of pyridines by conductance method at various temperatures and pressures in aqueous solution. The constants were increased as the temperature increase but decreased as pressure increase. From the constants various thermodynamic properties were calculated and discussed the dissociation reactions. It was estimated that alkylpyridines have exceptional dissociation reactions.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.576-582
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• 2011

Various 2-amino-6-[3-(substituted phenyl)-5-phenyl-4,5-dihydropyrazol-1-yl]-4-(substituted phenyl)nicotinonitriles (3a-t) were designed and synthesized by clubbing two active anticonvulsant pharmacophores pyrazole and pyridine. All the synthesized compounds possessed the pharmacophoric elements essential for good anticonvulsant activity. The anticonvulsant screening was performed by maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) tests. Two compounds 3i and 3s showed significant anticonvulsant activity in both the screens with $ED_{50}$ values 17.5 mg/kg and 22.6 mg/kg respectively in MES screen and 154.1 mg/kg and 242.6 mg/kg respectively in scPTZ screen. They were also found to have no acute toxic effects in mice when tested at elevated doses.

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.355-356
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• 2006

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2299-2303
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• 2010

A new approach to the use of potassium peroxodisulphate as an oxidizing reagent is proposed and applied to the case of oxidative aromatization of 1, 4-dihydropyridines with cetyltrimethylammonium peroxodisulfate, a phase transfer oxidant. We demonstrate how it is possible to increase the reactivity of potassium peroxodisulphate in the presence of phase transfer catalyst. Dealkylation in case of 4-n-alkyl/n-alkenyl was not obtained.

• Archives of Pharmacal Research
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• v.17 no.5
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• pp.298-303
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• 1994

4-Arylazo-1H-pyrazol-3, 5-idimines 1a-c reacted with bromomalononitrile (2) to yield the corresponding imidazo[1, 2-b]pyrazoles 3a-c. The latter reacted with some active methylene compounds and with .alpha.-cinnamonitriles to afford the corresponding pyrazoloimidazopyridines 6, 8, 9 and 15, respectively. Compounds 3 reacted with each of formic acid, formamide, trichlo-roacetonitrile and with guanidine to yield the corresponding pyrazoloimidazopyrimidines 16-19 respectively.

• Archives of Pharmacal Research
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• v.18 no.1
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• pp.27-30
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• 1995

The Hantzsh reaction of 7-hydroxy-8-methoxy-2-oxo-2H-benzopyran-6-carboxaldehyde (1) with ethyl acetoacetate and ammonia yields the dihydropyridine derivative 2 together with the pyridine derivative 3 and the eight membred ring derivative 4. Reaction of 1 with ethyl cyanoacetate and malononitrile gives the iminodicoumarin derivatives 5 and 6 respectiely. The latter compound was reacted with butan-2-one and acetophenone to produce the Michael adduct 71, b and the 2-aminopyridine derivatives 8a, b.