• Bulletin of the Korean Chemical Society
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• v.1 no.1
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• pp.1-4
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• 1980

During the study of the kinetics of Cl atom reactions by atomic fluorescence method we observed anomalous fluorescence emission for some atomic transitions. Instead of usual decrease of the fluorescence intensity by adding substrate, 1363 A transition $(^2P^{\circ}_{3/2}{\to}^2P_{1/2})$ intensity increased by adding substrate. From the normally behaved fluorescence lines the absolute rate constant for the reaction, Cl + $CH_3Cl{\to}$, was found to be $4.2{\times}10^{-13}$ cc/molecule sec at $20^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.29-31
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• 1993

Benzoin condensation reactions of furfurals and thiophenecarboxaldehydes in the presence of substituted benzyl and alkyl thiazolium salts were examined in order to improve the yield of the reaction and to examine the effect of the electronic nature of the catalysts. Thiophene derivatives gave thenils as the major products in low yields while furan derivatives gave only furoins in moderate to high yields.

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.47-50
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• 1989

The methanolysis reactions of phenylacetyl chlorides have been investigated in methanol-acetonitrile mixtures at temperatures ranging - $15.0-0.0^{\circ}C.$ Substituent and solvent effects on the rate supported an associative $S_N2$ mechanism for the solvolysis. Activation parameters indicated that the reaction is entropy controlled, while the a/s ratios of the Taft's solvactochromic correlation proved to be remarkably constant with a typical value of 0.50 that is consistent for the reactions proceeding by a typical $S_N2$ path.

• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.839-844
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• 1995

The kinetics and mechanism of the reactions of phenyl benzoates with benzylamines and pyrrolidine are investigated in acetonitrile. The variations of ρX (ρXY>0) and ρZ (ρYZ<0) with respect to the substituent in the substrate (σY) indicate that the reactions proceed through a tetrahedral intermediate, T±, with its breakdown in the rate determining step. The large magnitudes of ρZ, ρXY and ρYZ as well as the effects of secondary kinetic isotope effects involving deuterated nucleophiles are also in line with the proposed mechanism.

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.1017-1020
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• 1999

The aminolysis reactions of thiophenyl phenylacetates with benzylamines are investigated in acetonitrile at 55.0℃. Relatively large selectivity parameters, βx≒ 1.5, βz = -1.5~-1.8 and βxz = 0.92 together with the valid reactivity-selectivity principle are consistent with stepwise acyl transfer mechanism with rate limiting expulsion of the leaving group, thiophenolate anion, from the tetrahedral intermediate, T ± . The first order kinetics with respect to the benzylamine concentration and the realtively large secondary kinetic isotope effect (kH / kD = 1.2-1.7) involving deuterated benzylamine nucleophiles suggest a four center type transition state in which concurrent leaving group departure and proton transfer are involved.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.380-384
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• 1987

Reactions of methylenethioxanthene (3) with n-propanethiol in the presence of di-t-butyl peroxide(DTBP) afforded preferentially propyl 9-thioxanthenylidenemethyl sulfide(8) rather than propyl 9-thioxanthenylmethyl sulfide(9) regardless of the concentration of n-propanethiol. On the other hand reactions of 3 with a low concentration of n-propanethiol in the presence of dibenzoyl peroxide(DBPO) gave 8, 1,2-bisthioxanthenylidene ethane(11), and thioxanthenylidenemethyl benzoate(12) but only 8 was formed at high concentration of the thiol. The formations of these products were rationallized by an electron transfer mechanism.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1244-1248
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• 1998

Ozonolysis reactions of cyclic olefins 1a-c and norbomene In in the presence of trifluoroactophenone 6 provided the corresponding cross-ozonides 7a-c and 7n. Further reactions of ozonides 7a-c and 7n with the independently prepared carbonyl oxide 11 gave diozonides of structure l0a-c and 10n. The ozonolysis of 1methylcyclopentene 12a and 1-methylcyclohexene 12b in the presence of trifluoroactophenone 6 provided exclusively ozonide 15 and 16 derived from capture of carbonyl oxide 13. All of the new ozonides have been isolated as pure substances and characterized by their 1H NMR and 13C NMR spectra.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1334-1336
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• 1998

Kinetic studies are carried out on the reactions of 2-chloro-2-propen-1-yl arenesulfonates with anilines and N,N-dimethylanilines in acetonitrilile at 45.0 ℃. The 2-chloro substituent is found to deactive the allyl moiety with considerable decrease in the rates. The sign and magnitude of the cross-interaction constant (ρxz 0.3) and the inverse secondary kinetic isotope effect (kH/kD 0.92) support an SN2 mechanism with a relatively tight transition state. The possibility of an SN2' mechanism can be safely precluded based on the ρxz values observed.

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.561-564
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• 1998

Solvent effects on the reactions of DANSYL and BANSYL chlorides with substituted pyridines have been investigated using two parameters of Taft's solvatochromic correlation and four parameters of Kirkwood-Onsager, Parker, Marcus, Hildebrand equation. The acetonitrile molecules accelerate charge separation of the reactants and stabilize the transition state. The coefficient of the solvent parameters provide a good information to predict and to analyze the reaction mechanism. The nucleophilic substitution reaction of DANSYL and BANSYL chlorides with substituted pyridines are ruled by the contribution of the change in dipole moment term and polarity-polarizability term.

• Journal of the Korean Chemical Society
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• v.63 no.5
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• pp.346-351
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• 2019

Mannich-type reactions of cyclic N-sulfimines with 2-trimethylsiloxyfuran and pyrazolin-5-one have been developed using phosphoric acid (PA) as an organocatalyst. 2-Trimethylsiloxyfuran underwent a vinylogous Mannich-type reaction with cyclic N-sulfimines in the presence of the PA catalyst to give sulfamidate ${\gamma}$-butenolides in good yields and with high diastereoselectivities (up to 90% yield and 7:1 dr). In addition, the reaction between pyrazolin-5-one and a diverse range of cyclic N-sulfimines provided access to sulfamidates in good to high yields (up to 94% yield).