• Bulletin of the Korean Chemical Society
• /
• v.12 no.1
• /
• pp.101-103
• /
• 1991

The kinetic isotope effects (KIE) are determined for the reactions of benzyl benzenesulfonates (BBS), ethyl benzenesulfonates (EBS) and phenacyl benzensulfonates (PAB) with deuterated benzylamine nucleophiles. The inverse secondary ${\alpha}$-deuterium KIE observed were somewhat smaller than those for the corresponding reactions with aniline nucleophiles. The primary $KIE_s$ obtained with PAB were slightly greater than those for the corresponding reactions with anilines, which suggested that the inverse secondary KIE is decreased due to a relatively earlier transition state for bond-making with little change in the hydrogen bonding strength to the carbonyl oxygen.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.7
• /
• pp.585-589
• /
• 1994

Second-order rate constants have been measured spectrophotometrically for the nucleophilic substitution reactions of S-p-nitrophenyl thiobenzoate with various anionic nucleophiles including 6 ${\alpha}$-effect nucleophiles. A good Bronsted correlation has been observed for the reactions with 7 aryloxides. However, p-chlorothiophenoxide and hydroxide ions exhibit significantly positive and negative deviations, respectively, from the Bronsted plot. The deviations are attributed to the effect of polarizability and solvation rather than a change in the reaction mechanism. The ${\alpha}$-effect nuceophiles except highly basic ones demonstrate remarkably enhanced nucleophilicity. The effects of solvation and/or polarizability are proposed to be important for the cause of the ${\alpha}$-effect.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.7
• /
• pp.653-655
• /
• 1996

A comparative molecular field analysis (CoMFA) was carried out for the correlation of the transition state structures and the reaction rates for the SN2 reaction of 4-nitrophenyl benzoate and its sulfur analogs with anionic nucleophiles. The CoMFA analysis showed that both steric and electrostatic effects are important, and the steric contribution increased when nucleophiles are alkoxides or arylsulfides. In this study, we have demonstrated that the CoMFA analysis can be expanded beyond the scope of dealing with reactants and products. The reactant complex and transition state conformations generated along the reaction path can be more appropriately used for the correlation of structures and reaction rates.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.11
• /
• pp.1617-1618
• /
• 2004

• Bulletin of the Korean Chemical Society
• /
• v.19 no.12
• /
• pp.1392-1395
• /
• 1998

• Bulletin of the Korean Chemical Society
• /
• v.30 no.10
• /
• pp.2381-2386
• /
• 2009

The tetrakis(thio)-substituted-1,4-benzoquinone products 4a-e, 6, 7, and the mono(alkoxy)-tris(thio)-substituted-1,4- benzoquinone products 5a-e and 8a-e were synthesized from the reactions of p-chloranil with some thiols and mixture of two different thiol compounds in alcohol in the presence of $Na_2CO_3$ at room temperature. The structures of the novel S,S,S,S- and S,S,S,O- substituted products, which were obtained by the reactions of p-chloranil as a starting compound with n-propanethiol, n-pentanethiol, n-decanethiol, n-dodecanethiol, 2-methyl-2-propanethiol, and mixture of n-decanethiol and n-cyclohexanethiol as S-nucleophiles, were characterized by spectroscopic methods.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.6
• /
• pp.989-992
• /
• 2005

Dynamic kinetic resolution of $\alpha$-bromo carboxylic acid derivatives in nucleophilic substitution with chiral $\alpha$-amino ester nucleophiles in the presence of TBAI and DIEA has been investigated for stereoselective syntheses of 1,1'-iminodicarboxylic acid derivatives. Nucleophilic substitutions with various chiral $\alpha$-amino esters gave iminodiacetates 2-8 with stereoselectivities up to 87 : 13 dr. Also, the reactions of N-($\alpha$-bromo-$\alpha$-phenylacetyl)-L-alanine methyl ester with L-alanine, D-alanine and glycine methyl ester nucleophiles afforded N-carboxyalkyl dipeptide analogues 10-12 up to 90 : 10 dr.

• Bulletin of the Korean Chemical Society
• /
• v.11 no.1
• /
• pp.7-10
• /
• 1990

The interaction of tetraphenylphthalic anhydride with o-chlorotoluene under Friedel-Craft condition gives 2-(4-chloro-3-methyl)benzoyl-3,4,5,6-tetraphenyl benzoic acid(1), which on reaction with hydrazine derivatives gave phthalazinones (2a-d). The behaviour of (2a) towards carbon electrophiles and carbon nucleophiles has been investigated. The chlorophthalazinones (4a) also has been synthesized from the action of $PCl_5/POCl_3$ on (2a). The behaviour of (4a) towards nitrogen, and oxygen nucleophiles also have been described.

• Bulletin of the Korean Chemical Society
• /
• v.11 no.5
• /
• pp.435-438
• /
• 1990

Primary and secondary ${\alpha}$-deuterium kinetic isotope effects are determined with deuterated aniline nucleophiles in the nucleophilic substitution reactions of benzyl benzenesulfonates and 1-phenylethyl benzenesulfonates in acetonitrile at 30.0^{\circ}C. The $k_H/k_D$ values support our previous conclusions regarding the transition state structures proposed for the two reactions based on the cross-interaction constants ${\rho}_{ij}$; the former is a typical $S_N2$ reaction whereas in the latter the four-center transition state may be involved.

• Bulletin of the Korean Chemical Society
• /
• v.12 no.3
• /
• pp.295-301
• /
• 1991

The nucleophilic substitution reactions of p-substituted benzenesulfonyl chlorides wiht p-substituted anilines were carried out in 1,1,1,3,3,3-hexafluoro-2-propanol and 2-propanol mixtures. The salt effect was observed to be inhibited by the reaction of 1,1,1,3,3,3-hexafluoro-2-propanol with nucleophiles. To investigate the effectiveness of the salt for the nucleophilic substitution reaction the relative salt effect was determined. According to the comparison with the inhibitive salt effect and the substituent effects for the substrates and nucleophiles, the reactions were predicted to be controlled by the salt effect more than substituent effect in HFP-PrOH mixtures.