• Bulletin of the Korean Chemical Society
• /
• v.21 no.6
• /
• pp.611-612
• /
• 2000

A facile synthetic route for the preparation of 4-halobutyl benzoates has been developed. 4-Chloro-, bromo-and iodobutyl benzoates can be easily prepared from the reaction of benzoyl chloride and metal halides in THF under extremely mild conditions. 4-Halo groups were easily controlled by selecting suitable metal halides.

• Bulletin of the Korean Chemical Society
• /
• v.12 no.4
• /
• pp.406-410
• /
• 1991

Second order rate constants have been measured spectrophotometrically for reactions of 4-nitrophenyl substituted benzoates with various aryloxides and aryl benzoates with p-chlorophenoxide. The reactivity has exhibited significant dependences on the electronic nature of the substituent in the acyl moiety of the substrate and in the nucleophilic phenoxide, while the substituent in the leaving phenoxide has little influenced the reactivity. The Bronsted coefficient $\beta$ values so obtiained support that the present acyl transfer reaction proceeds via a stepwise mechanism in which the nucleophilic attack would be the rate-determining step. Interestingly, the magnitude of the $\betaacyl$ and $\beta$ nuc increases with increasing reactivity, implying that the reactivity selectivity principle is not operative in the present system. The failure of the reactivity selectivity principle is attributed to a change in transition state structure upon the substituent variation in the present acyl transfer reaction.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.1
• /
• pp.49-55
• /
• 2000

A series of m-, and p-substituted phenyl 2-thiophenecarboxylates and benzoates was prepared by the reaction of the corresponding acyl chlorides and phenols. Their $^1H$ and $^{13}C$ NMR chemical shifts were analyzed using single substituent parameter (S SP) and dual substituent parameter (DSP) methods. The relative aromaticity index of thiophene was estimated to be 0.92 from the plot of the chemical shift of the carbonyl carbons of the thienoyl esters against chemical shift of the carbonyl carbons of the benzoyl esters.

• Bulletin of the Korean Chemical Society
• /
• v.7 no.2
• /
• pp.106-108
• /
• 1986

Exciton chirality method was applied for the determination of absolute configuration of panaxynol, a poly-yne compound from Panax ginseng roots for the first time. The circular dichroic spectra of panaxynol benzoates show the negative chirality at ${\lambda}_{ext}$, indicating the S configuration of C-3 chiral center.

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

• Journal of Food Hygiene and Safety
• /
• v.16 no.1
• /
• pp.53-60
• /
• 2001

A study has been carried out to estimate the average daily intakes of sorbates, benzoates, and and esters of $\rho$-hydroxybenzoic acid commonly used in Korea. The estimation of daily intakes was based on individual dietary intakes in “National Health and Nutrition Survey in 1998”and the the contents of preservatives from 264 samples. Estimated daily intakes(EDI) of sorbates, benzoates, esters of $\rho$-hydroxybenzoic acid were 0.22, 0.015, and 0.004 mg/kg bw/day, respectively. When assuming the standard body weight of 55 kg for Korean, ratios to acceptable daily intake (ADI) of sorbates, benzoates, and esters of $\rho$-hydroxybenzoic acid were 0.88, 0.30, and 0.04%, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.471-476
• /
• 2014

A kinetic study on aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (2a-k) in 80 mol % $H_2O/_20mol%$ DMSO at $25.0^{\circ}C$ is reported. The Br${\emptyset}$nsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (2g) with a series of cyclic secondary amines curves downward (e.g., ${\beta}_1=0.25$, ${\beta}_2=0.85$ and $pK_a^o=10.3$), which is typical of reactions reported to proceed through a stepwise mechanism with a change in ratedetermining step (RDS). The Hammett plot for the reactions of 2a-k with piperidine consists of two intersecting straight lines, while the corresponding Yukawa-Tsuno plot exhibits an excellent linear correlation with ${\rho}_X=1.15$ and r = 0.59. Thus, it has been concluded that the nonlinear Hammett plot is not due to a change in RDS but is caused by stabilization of substrates through resonance interactions between the electron-donating substituent and the C=O bond. Substrates possessing a substituent at the 2-position of the leaving aryloxide deviate negatively from the curved Br${\emptyset}$nsted-type plot for the reactions of Y-substituted-phenyl benzoates (3a-i), implying that the steric hindrance exerted by the substituent at the 2-position is an important factor which governs the reactivity of Y-substituted-phenyl benzoates.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.3
• /
• pp.689-693
• /
• 2010

Second-order rate constants ($k_{CN^-}$) have been measured for nucleophilic substitution reactions of Y-substituted phenyl benzoates (1a-r) with $CN^-$ ion in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$. The Br${\o}$nsted-type plot is linear with ${\beta}_{1g}$ = -0.49, a typical ${\beta}_{1g}$ value for reactions reported to proceed through a concerted mechanism. Hammett plots correlated with ${\sigma}^{\circ}$ and ${\sigma}^-$ constants exhibit many scattered points. In contrast, the Yukawa-Tsuno plot for the same reaction exhibits excellent linearity with ${\rho}_Y$ = 1.37 and r = 0.34, indicating that a negative charge develops partially on the oxygen atom of the leaving aryloxide in the rate-determining step (RDS). Although two different mechanisms are plausible (i.e., a concerted mechanism and a stepwise pathway in which expulsion of the leaving group occurs at the RDS), the reaction has been concluded to proceed through a concerted mechanism on the basis of the magnitude of ${\beta}_{1g}$ and ${\rho}_Y$ values.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.9
• /
• pp.911-913
• /
• 1997

• Bulletin of the Korean Chemical Society
• /
• v.16 no.7
• /
• pp.569-571
• /
• 1995