• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.985-990
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• 1994

Cross-interaction constants, ${\rho}^e_{XY}$, ${\rho}_{YZ}$ and ${\rho}_{XZ}$ are defined using observed rate constant, k_N=(k_1/k_{-1})k_2=Kk_2$, for the stepwise carbonyl addition reactions involving the rate-limiting breakdown of a tetrahedral intermediate $(T^{\pm})$. Abundant experimental evidence in the literature enables us to determine signs for the three constants for such mechanism, ${\rho}^e_{XY}$>0, ${\rho}_{YZ}$<0 and ${\rho}_{XZ}$0. These are in contrast to those for the concerted $S_N2$ mechanism, ${\rho}_{XY}$<0, ${\rho}_{YZ}$>0 and ${\rho}_{XZ}$, and provide useful mechanistic criteria. In the light of these criteria, mechanisms of some nucleophilic reactions of carbonyl compounds are re-examined.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.426-427
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• 1987

• Bulletin of the Korean Chemical Society
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• v.11 no.4
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• pp.260-262
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• 1990

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.133-135
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• 1988

Kinetics and mechanism of the nucleophilic substitution reactions of phenacyl bromides with anilines in methanol-acetonitrile mixtures at $45.0^{\circ}C$ are reported. The reaction is found to proceed via $S_N2$ process, but the magnitudes of cross interaction constants, ${\rho}_{XY}$, between substituents X in the nucleophile and Y in substrate were unusually small, even after allowing for the fall off due to non-conjugative intervening -CO group in the reactant. As in the other phenacyl derivatives, the resonance shunt phenomenon was invoked to explain the remarkable diminuation of the $|{\rho}_{XY}|$ values.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.376-378
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• 1988

Results of kinetic studies on the reactions of benzyl chlorides with anilines and benzylamines are reported. Analyses of the cross interaction constants relevant to the degree of bond formation, ${\rho}_{XY}$ and ${\lambda}_{XY}$, are carried out. The magnitudes of the two parameters indicated that the degree of bond formation in the transition state is the typical of that expected for an $S_N2$ reaction, but the reactions with benzylamines appear to have a slightly less degree of bond formation compared with the reactions with anilines.

• Bulletin of the Korean Chemical Society
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• v.10 no.5
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• pp.459-462
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• 1989

The transition state (TS) structure for the reactions of phenacyl benzenesulfonates with N,N-dimethylanilines (DMA) is investigated using various selectivity parameters, especially with cross-interaction constants, ${\rho}_{ij}$, ${\beta}_{ij}$ and ${\lambda}_{ij}$. The trends in reactivity were similar to aniline series but the TS was found to be somewhat looser than that for aniline series. It was found that the RSP and BEP principle hold within the DMA series but are violated between two different reaction series with DMA and aniline.

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.179-182
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• 1988

A simple correlation between cross interaction constants ${\rho}_{ij}$ and bond lengths in the transition state was obtained ; it has been shown that ${\rho}_{ij}$ corresponds to force constant of activation, which in turn is related to bond length by Badger's rule involving only universal constants. A satisfactory correlation between 4-31G ab initio calculated values of bond length and force constant for C-X streching in the transition state of the methyl transfer reaction, $X^-\;+\;CH_3X\;=\;XCH_3\;+\;X^-$, indicated that Badger's rule can be extended to bonds in the transition state. Independence of ${\rho}_{ij}$ values from the variable charge transmission of reaction centers has been demonstrated with nearly constant, experimentally determined I${\rho}$XYI values, and hence similar degree of bond formation, for various $S_N2$ reactions.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.350-351
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• 1987

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1754-1758
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• 2014

The nucleophilic substitution reactions of bis(Y-aryl) chlorothiophosphates (1) with X-pyridines are investigated kinetically in acetonitrile at $35.0^{\circ}C$. The free energy relationships with both X and Y are biphasic concave upwards with a break point at X = 3-Ph and Y = H, respectively. The sign of cross-interaction constants (CICs; ${\rho}_{XY}$) is positive with all X and Y. Proposed mechanism is a stepwise process with a rate-limiting leaving group departure from the intermediate with all X and Y. The kinetic results of 1 are compared with those of Y-aryl phenyl chlorothiophosphates (2). In the case of Y = electron-withdrawing groups, the cross-interaction between Y and Y, due to additional substituent Y, is significant enough to change the sign of ${\rho}_{XY}$ from negative with 2 to positive with 1, indicative of the change of mechanism from a rate-limiting bond formation to bond breaking.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3597-3601
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• 2013

The reactions of bis(Y-aryl) chlorothiophosphates (1) with substituted anilines and deuterated anilines are investigated kinetically in acetonitrile at $55.0^{\circ}C$. The Hammett plots for substituent Y variations in the substrates show biphasic concave upwards with a break point at Y = H. The cross-interaction constants (${\rho}_{XY}$) are positive for both electron-donating and electron-withdrawing Y substituents. The kinetic results of 1 are compared with those of Y-aryl phenyl chlorothiophosphates (2). The cross-interaction between Y and Y, due to additional substituent Y, is significant enough to result in the change of the sign of ${\rho}_{XY}$ from negative with 2 to positive with 1. The effect of the cross-interaction between Y and Y on the rate changes from negative role with electron-donating Y substituents to positive role with electron-withdrawing Y substituents, resulting in biphasic concave upward free energy correlation with Y. A stepwise mechanism with a rate-limiting leaving group departure from the intermediate involving a predominant frontside attack hydrogen bonded, four-center-type transition state is proposed based on the positive sign of ${\rho}_{XY}$ and primary normal deuterium kinetic isotope effects.