• Journal of the Korean Chemical Society
• /
• v.31 no.3
• /
• pp.207-214
• /
• 1987

Rates of solvblysis of benzyl chloride in ethanol-water mixtures have been measured at 30 and $40^{\circ}C$ under various pressures up 1.6 kbar. The plots of 1n k as a function of pressure are fitted to a second order function in p, and values of ${\Delta}V^{\neq}$and ${\Delta}{\beta}^{\neq}$ are obtained from the results. Also the values of various pseudo thermodynamic quantities were evaluated from the rate constants. The relationships of the 1n k to $Q_w$ or 1n $C_w$ indicate that the reaction proceeds through $S_N1$ mechanism. A comparison between the present and the previous results gives that the increasing order of ${\mid}{{\Delta}V_0}^{\neq}{\mid}$ and n-values are $p-Cl>p-H>p-CH_3$ and $p-CH_3>p-H.p-Cl$, respectively. From these results, it is believed substituent such as the $p-CH_3$group favors the $S_N1(1)$ character, while the p-Cl group leads to the $S_N1(2)$ character.

• Journal of the Korean Chemical Society
• /
• v.25 no.3
• /
• pp.152-159
• /
• 1981

The rates of solvolysis for p-nitrobenzyl chloride have been measured by the electric conductivity method in aqueous ethanol from 0.0 to 0. 5 mole fraction of ethanol under various pressures up to 1200bar at 50 and $60{\circ}C$. The activation parameters, ${\Delta}V_\0^{\neq},\ {\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ are evaluated from the rate constants. The results indicated that ${\Delta}V_\0^{\neq}$ exhibits an extremum behaviors near 0.3 mole fraction of ethanol and ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ near 0.1 mole fraction of ethanol. This behaviors are discussed in terms of solvent structure variation and the pressure dependences of ${\Delta}H^{\neq},\ {\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ are also discussed individually. The signs of the pressure dependence of ${\Delta}H^{\neq}$${\Delta}S^{\neq}$ are shown to be consistent with those required by the Maxwell relationships for classical thermodynamic systems.

• Journal of the Korean Chemical Society
• /
• v.32 no.6
• /
• pp.581-587
• /
• 1988

The solvolysis of substituted benzyl bromides was studied in binary solvent mixtures of acetone-water and ethanol-water at $25^{\circ}C$ and $45^{\circ}C$. The rate constants increase with electron-donating substituents in benzene ring and increasing of water contents in both of solvent mixtures. The sensitivity parameter (m) of the solvolysis of substituted benzyl bromides to solvent ionizing power (Y) was decreased in going from the electron-donating group to electron-withdrawing one, whereas their nucleophilic sensitivity increased continuously in going to above same substituents. It was shown that electron-donating (electron-withdrawing) groups make the transition state looser (tighter). The above results were consisted with the account for the potential energy surface model and the quantum mechanical approach.

• Journal of the Korean Chemical Society
• /
• v.30 no.1
• /
• pp.40-46
• /
• 1986

Rate constants for the solvolysis of o-methylbenzyl chloride were determined at 30$^{\circ}$ and 40$^{\circ}$C in aqueous ethanol mixtures under various pressures up to 1600 bar. From the rate constants, the activation parameters ${\Delta}V^{\neq}$, ${\Delta}{\beta}^{\neq}$, ${\Delta}H^{\neq}$, ${\Delta}S^{\neq}$ and${\Delta}G^{\neq}$ were evaluated. The values exhibit the extremum behavior at about 0.30 mole fraction of ethanol. This behavior is discussed in terms of electrostriction. To examine the reaction mechanism by Laidler and Eyring equation, we compared the rate constants with the dielectric constants of aqueous ethanol and the number of water molecule participated in the transition state. It was concluded that solvolytic reaction proceeds via $S_N$1 mechanism.

• Elastomers and Composites
• /
• v.48 no.1
• /
• pp.46-54
• /
• 2013

A new terpolymer, styrene-butadiene-benzyl methacrylate copolymer (BzMA-SBR) was synthesized by emulsion polymerization. After polymerization, XSBR ionomer was prepared by deprotection of benzyl group of BzMA through hydrolysis with NaOH. Carboxyl group contents can be controlled by changing the initial feed contents of BzMA. Structure of BzMA-SBR and XSBR were characterized by FTIR, $^1H$ NMR and DSC.

• Journal of the Korean Chemical Society
• /
• v.32 no.4
• /
• pp.291-296
• /
• 1988

Rates of the reaction for p-nitrobenzyl chloride, benzyl chloride and p-methylbenzyl chloride with pyridine in DMF solvent have been measured by an electric conductivity method at $40^{\circ}\;and\;50^{\circ}C$ under various pressures. From those rate constants, the activation parameters ${\Delta}V^{\neq},\;{\Delta}{\beta}^{\neq},\;{\Delta}H^{\neq},\;{\Delta}S^{\neq},\;{\Delta}G^{\neq}$) were evaluated. ${\Delta}V^{\neq}\;and\;{\Delta}{\beta}^{\neq}$ are both negative valued, but ${\Delta}H^{\neq}$ is positive and ${\Delta}S^{\neq}$ is large negative value. From the evaluation of the initial state and transition state which was resulted from substituents and pressure, it was found that this reaction proceeds through bimolecular reaction.

• Journal of the Korean Chemical Society
• /
• v.28 no.6
• /
• pp.366-373
• /
• 1984

Methanolysis rates of benzylbenzenesulfonates, substituted both on the substrate (Y) and on the leaving group (Z), were determined in MeOH-MeCN mixtures. The results showed that the reaction proceeds via the dissociative $S_N2$ mechanism, in which bond breaking proceeds in greater degree compared to bond formation at the transition state(TS). Multiple Hammett correlation analysis showed that the cross term, ${\rho}_{YZ}$, is very small and hence the cross interaction of two substituents, Y and Z, at the TS is not important, supporting the dissociative $S_N2 $ type mechanism. While transition state variations predicted by the quantum mechanical model is shown to agree in general with the experimental results, those predicted by the potential energy surface model failed to account for the leaving group effect properly.

• Journal of the Korean Chemical Society
• /
• v.23 no.1
• /
• pp.37-41
• /
• 1979

The kinetics of the reaction of benzyl m-nitrobenzenesulfonate with m-and p-substituted N,N-dimethylanilines in acetone have been investigated by an electric conductivity method. The effects of substituents on the reactivity of N,N-dimethylaniline and the existence of linear free energy relationship were discussed. The rate constants k were in the range 2.55∼487 $10^{-4}l{\cdot}mol^{-l}{\cdot}sec^{-1} (35^{\circ}C)$ and increased with the electron donating ability of substituents. In the present reaction, the Hammett plot was correlated with ${\sigma}$ substituent constant, especially using the new ${\sigma}$ value of 0.35 in p-MeO and it's ${\rho}$ value was found to be -1.37. r value for the reaction was very large than the value obtained in the reaction of benzyl bromide. $Br{\"{o}}nsted$ linear relationship was shown between rate constant and basicites except for p-MeO resulted from solvent effect. From the Bronsted plot, this reaction was suggested that the cleavage of the C${\cdot}{\cdot}{\cdot}$O bond in the $S_N2$ transition state proceed the bond formation.

• Journal of the Korean Chemical Society
• /
• v.33 no.1
• /
• pp.31-36
• /
• 1989

The second-order rate constants for the nucleophilic substitution reactions of para-substituted benzyl nitrates with para-substituted anilines in acetonitrile were conductometrically determined. Hammett ${\rho}$x and ${\rho}$y values and Bronsted ${\beta}$ values were obtained from these kinetic data. The reactions of Benzyl nitrates with the series of anilines showed linear Hammett plots with negative slopes. For the change of substituents in the benzyl nitrates, nonlinear Hammett plots with a concave upwards curve were obtained. We applied the potential energy surface and the quantum mechanical models in order to examine the transition state variations caused by changes in substituents on the nucleophile and the substrate. The results showed that the reaction was proceeded via the $S_{N}2$-type reaction mechanism in which the extent of bond-formation was greatly changed depending on the property of the substituents in substrate.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.8
• /
• pp.378-384
• /
• 2018

$C_9H_7NHCrO_3Cl$ was synthesized by reacting $C_9H_7NH$ with chromium (VI) trioxide. The structure of the product was characterized by FT-IR (Fourier transform infrared) spectroscopy and elemental analysis. The oxidation of benzyl alcohol by $C_9H_7NHCrO_3Cl$ in various solvents showed that the reactivity increased with increasing dielectric constant(${\varepsilon}$) in the following order: DMF (N,N'-dimethylformamide) > acetone > chloroform > cyclohexane. The oxidation of alcohols was examined by $C_9H_7NHCrO_3Cl$ in DMF. As a result, $C_9H_7NHCrO_3Cl$ was found to be an efficient oxidizing agent that converts benzyl alcohol, allyl alcohol, primary alcohols, and secondary alcohols to the corresponding aldehydes or ketones (75%-95%). The selective oxidation of alcohols was also examined by $C_9H_7NHCrO_3Cl$ in DMF. $C_9H_7NHCrO_3Cl$ was the selective oxidizing agent of benzyl, allyl and primary alcohol in the presence of secondary ones. In the presence of DMF with an acidic catalyst, such as $H_2SO_4$, $C_9H_7NHCrO_3Cl$ oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, and $m-NO_2$). Electron donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (${\rho}$) was -0.69 (308K). The observed experimental data were used to rationalize hydride ion transfer in the rate-determining step.