• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3279-3282
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• 2010

The reaction rates of 4-X-2,6-dinitrochlorobenzenes (X = $NO_2$, CN, $CF_3$) with Y-substituted benzylamines (Y = p-$OCH_3$, p-$CH_3$, H, p-Cl) in MeOH-MeCN mixtures were measured by conductometry at $25^{\circ}C$. It was observed that the rate constant increased in the order of X = $NO_2$ > CN > $CF_3$ and in the order of Y = p-$OCH_3$ > p-$CH_3$ > H > p-Cl. When the solvent composition was varied, the rate constant increased in the order of 100% MeOH < 50% (v/v) MeOH-MeCN < 100% MeCN. These results may be ascribed to the formation of hydrogen bonds between the alcoholic hydrogen and nitrogen of benzylamines in groud state (GS). We conclude that the reaction takes place via $S_NAr$ base on the transition state parameters ${\rho}x$, ${\rho}Y$, $\beta_{nuc}$, and solvent effects.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1253-1256
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• 1998

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.712-715
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• 1996

Kinetic studies are carried out on the reactions of N-methyl-N-phenylcarbamoyl chlorides with benzylamines in acetonitrile. The selectivity parameters, ρX (=-0.6~-0.8), ρY (=1.0-1.1), and ρXY (=-0.14), suggest that the reaction proceeds by an SN2 mechanism. Kinetic isotope effects, kH/kD, involving deuterated nucleophiles (XC6H4CH2ND2) are all inverse type (<1.0), and the trends of changes in the magnitude are consistent with those expected for the observed negative sign of ρXY(=∂ρX/∂σY = ∂ρY/∂σX < 0). The relatively low activation enthalpies also support the proposed mechanism.

• Bulletin of the Korean Chemical Society
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• v.17 no.3
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• pp.254-257
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• 1996

Nucleophilic substitution reactions of 1- and 2-naphthylethyl arenesulfonates, 2 and 3, with anilines and benzylamines in methanol at 65.0 ℃ are investigated. The rates are slower than those for the corresponding derivatives of 2-phenylethyl arenesulfonates, 1, which can be attributed to a greater degree of positive charge stabilization at Cα in the transition state (TS) by a greater electron supply from a phenyl ring compared to a naphthyl ring. The mechanism for the two naphthylethyl systems are similar to that for the 2-phenylethyl derivatives, except that the transition state is formed at somewhat an earlier position along the reaction coordinate. The secondary kinetic isotope effects involving deuterated nucleophilies indicate that naphthylethyl series are sterically more crowded in the TS than 2-phenylethyl system. The data in this work can not elucidate the possible participation of the aryl-assisted pathway in the reaction.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1887-1890
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• 2009

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2427-2430
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• 2012

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2535-2538
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• 2007

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1873-1876
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• 2006

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.221-224
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• 2002

Nucleophilic addition reactions of benzylamines (BA; $XC_6H_4CH_2NH_2$) to ethyl-${\alpha}$-cyanocinnamates (ECC;$YC_6H_4CH$=C(CN)COOEt) have been investigated in acetonitrile at $30.0^{\circ}C$. The rate is first order with respect to BA and ECC. The rate is slower than that expected from the additive effect of ${\sigma}^-$ or $R^-$ for the activating groups (CN and COOEt). Natural. bond orbital ${\pi}^{\ast}_{c=c}$ calculations show that the contribution of COOEt group may not be fully effective despite the coplanar molecular structure. The selectivity parameters including the cross-interaction constant (${\rho}_{xy}$ = -0.22) indicate that the addition occurs in a single step. The kinetic isotope effects ($k_H/k_D$=2.5-2.8) involving deuterated BA ($XC_6H_4CH_2ND_2$) nucleophiles and activation parameters (${\Delta}H^{\neq}=4{\sim}6\;kcal\;mol^{-1};{\Delta}S^{\neq}=-45{\sim}-52\;e.u.$) suggest a cyclic transition state in which N-$C_{\alpha}$ and H-$C_{\beta}$ bonds are formed concurrently.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.191-196
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• 2008

Kinetic studies of the reactions of a-bromoacetanilides [YC6H4NHC(=O)CH2Br] with substituted benzylamines (XC6H4CH2NH2) have been carried out in dimethyl sulfoxide at 35.0 oC. The Hammett plots for substituent (Y) variations in the substrate (log kN vs. sY) are biphasic concave upwards/downwards with breaks at Y = 4-Cl (sY = 0.23). The Hammett coefficients rY and the cross-interaction constant rXY (= +0.16) are positive for sY 0.23, while the rY values are positive/negative [rY > 0 for X = (4-MeO and 4-Me) and rY < 0 for X = (H, 4-Cl and 3-Cl)] and the rXY (= -1.51) value is negative for sY ³ 0.23. Based on these and other results, the benzylaminolyses of a-bromoacetanilides are proposed to proceed through rate-limiting expulsion of the bromide leaving group from a zwitterionic tetrahedral intermediate, T, with a bridged transition state for s Y 0.23, while the reaction proceeds through concerted mechanism with an enolate-like TS in which the nucleophile attacks the a-carbon for s Y ³ 0.23.