• Journal of the Korean Chemical Society
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• v.58 no.1
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• pp.17-24
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• 2014

The oxidative decarboxylation of phenylsulfinylacetic acid (PSAA) by Cr(VI) in 20% acetonitrile -80% water (v/v) medium follows overall second order kinetics, first order each with respect to [PSAA] and [Cr(VI)] at constant [$H^+$] and ionic strength. The reaction is acid catalysed, the order with respect to [$H^+$] is unity and the active oxidizing species is found to be $HCrO_3^+$. The reaction mechanism involves the rate determining nucleophilic attack of sulfur atom of PSAA on chromium of $HCrO_3^+$ forming a sulfonium ion intermediate. The intermediate then undergoes ${\alpha}$,${\beta}$-cleavage leading to the liberation of $CO_2$. The product of the reaction is found to be methyl phenyl sulfone. The operation of substituent effect shows that PSAA containing electron-releasing groups in the meta- and para-positions accelerate the reaction rate while electron withdrawing groups retard the rate. An excellent correlation is found to exist between log $k_2$ and Hammett ${\sigma}$ constants with a negative value of reaction constant. The ${\rho}$ value decreases with increase in temperature evidencing the high reactivity and low selectivity in the case of substituted PSAAs.

• The Korean Journal of Pesticide Science
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• v.7 no.2
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• pp.155-158
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• 2003

2-Imino-1,3-thiazolines 1 show selective antifungal activity against pyricularia oryzae by new mode of action. A synthesis of novel 2-cyano-l,3-thiazolines 2 in which cyano moiety is substituted in imino group at C-2 of 1 is described. The lone pair electrons of sulfur and nitrogen as well as strong electron withdrawing cyano substituent in 1,3-thiazoline scaffold would effect the biological activity of 2-imino-1,3-thiazoline series. Regiospecific nucleophilic attack of thiourea 4 for $\gamma$-chloro-$\beta$-ketoacetoacetanilide 3 followed by acid catalyzed dehydration gave 2.

• Bulletin of the Korean Chemical Society
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• v.15 no.6
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• pp.473-477
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• 1994

Second-order rate constants have been measured spectrophotometrically for the nucleophilic substitution reactions of aryl substituted benzenesulfonates $(1,\;X-C_6H_4SO_2-OC_6H_4-Y)$ with aryloxides $(Z-C_6H_4O^{-})$ and ethoxide $(EtO^-)$ in absolute ethanol at $25^{circ}C$. The nucleophilicity of aryloxides increases with increasing electron donating ability of the substituent (Z) on aryloxides, and results in a good Hammett correlation with $\sigma^{-}$ constant. The reactivity of 1 toward aryloxides and ethoxide shows also significant dependence on the electronic nature of the substituent X and Y. Large positive ${\sigma}_{acyl}$ values have been obtained for the reaction of 1 with phenoxide and ethoxide, indicating that the leaving group departure is little advanced at the transition-state of the rate-determining step. This has been further supported from the fact that ${\sigma}^-$ constant gives extremely poor Hammett correlation, while ${\sigma}^0$ does reasonably good correlation for the reaction of 1 with ethoxide. Thus, the present sulfonyl-transfer reaction is proposed to proceed via a ratedetermining attack of nucleophile to the sulfur atom of 1 followed by a fast leaving group departure.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.567-574
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• 1988

Kinetic studies on the vanadium(IV)-catalyzed oxidation of dimethylsulfoxide by hydrogen peroxide in water and aqueous methanol and ethanol show that the reaction is the first order in the concentration of dimethylsulfoxide and hydrogen peroxide, respectively. Activation parameters are also measured for the oxidation of dimethylsulfoxide. It is suggested that the rate determining step is a process involving oxidation of dimethylsulfoxide as the result of nucleophilic attack by the sulfur on the O-O bond of vanadium(V)-peroxide complex.

• The Korean Journal of Pesticide Science
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• v.5 no.2
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• pp.13-17
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• 2001

A synthesis of new 2-phenylimino-1,3-thiazolines 2 for the purpose of development of new agrochemical fuugicide was described. Reaction of chlorine with diketene followed by treatment of benzylamine without isolation of intermediate 8a gave ${\gamma}-chloro-{\beta}-keto$ benzylamide 10a. Thioureas 4 obtained from the reaction of methyl isothiocyanate with aniline derivatives were subjected to 10a in acetone solution to afford the corresponding 2-phenylimino-1,3-thiazoline hydrochloric acid salts 2 through unisolable inltermediates 11 and 12. The plausible reaction mechanism including nucleophilic attack of sulfur assisted neighboring nitrogen lone pair electron on phenyl of thiourea 4 was discussed.

• Journal of the Korean Chemical Society
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• v.27 no.2
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• pp.157-164
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• 1983

N-Methylidene-2,6-diethylaniline (III) was prepared by the reaction of 2,6-diethylaniline (II) with an excess paraformaldehyde. The protons of N=$CH_2$in the compound III exhibited a second order NMR spectrum. The compound III reacted with bifunctional chlorocarbonylsulfenyl chloride(IV) to give N-(chloromethyl)-N-(2,6-diethylphenyl)-carbamoylsulfenyl chloride(V). The reaction of the compound V with various alcohols resulted in the formation of Alkyl N-(chloromethyl)-N-(2,6-diethylphenyl)-carbamoylsulfenate esters(VI${\sim}$XVI) in 71${\sim}$95% yields. The compound VI${\sim}$XVI decomposed gradually, but the thermal rearrangement of S-O bonding to S=O bonding was not found. The nucleophilic attack of an excess alcohol to the compound Ⅴ was made on both divalent sulfur and ${\alpha}$-carbon of N-chloromethyl group. The corresponding substituted products(XVII, XVIII) had considerable stability.