• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.843-847
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• 2012

The nucleophilic substitution reactions of dibutyl chlorothiophosphate (4S) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $55.0^{\circ}C$. The obtained deuterium kinetic isotope effects (DKIEs;$k_H/k_D$) are primary normal ($k_H/k_D$ = 1.10-1.35). A concerted mechanism involving predominant frontside nucleophilic attack is proposed on the basis of the primary normal DKIEs and selectivity parameters. Hydrogen bonded, four-center-type transition state is proposed. The steric effects of the two ligands on the anilinolysis rates of the chlorothiophosphates are discussed. The anilinolyses of P=S systems are compared with those of their P=O counterparts on the basis of the reactivities, thio effects, selectivity parameters, and DKIEs.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1829-1834
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• 2013

The nucleophilic substitution reactions of Y-aryl ethyl isothiocyanophosphates with substituted X-anilines and deuterated X-anilines were investigated kinetically in acetonitrile at $75.0^{\circ}C$. The free energy relationships with X in the nucleophiles exhibited biphasic concave downwards with a break point at X = H. A stepwise mechanism with rate-limiting bond formation for strongly basic anilines and with rate-limiting bond breaking for weakly basic anilines is proposed based on the negative and positive ${\rho}_{XY}$ values, respectively. The deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) changed gradually from primary normal with strongly basic anilines, via primary normal and secondary inverse with aniline, to secondary inverse with weakly basic anilines. The primary normal and secondary inverse DKIEs were rationalized by frontside attack involving hydrogen bonded, four-center-type TSf and backside attack involving in-line-type TSb, respectively.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3245-3250
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• 2011

The nucleophilic substitution reactions of diisopropyl chlorophosphate (3) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $55.0^{\circ}C$. The anilinolysis rate of 3 is rather slow to be rationalized by the conventional stereoelectronic effects. The obtained deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are secondary inverse ($k_H/k_D$ = 0.71-0.95) with maximum magnitude at X = H.A concerted mechanism involving predominant backside nucleophilic attack is proposed on the basis of the secondary inverse DKIEs.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권3호
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• pp.195-200
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• 2000

The kinetics of the reaction between carbonyl sulfide and aqueous monoethanolamine were studied over a range of temperature (298-348 K) and amine concentrations using a wetted-sphere absorber. The key physicochemical properties used to interpret the data included the solubility and diffusivity of the COS in the aqueous amine solution. The experimental data were interpreted using a zwitterion mechanism, which produced an Arrhenius plot with third-order kinetic rate constants. The fit of these data was $K_3$=$1.32\times10(sup)10exp(\frac{-6136}{T}}$

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4403-4407
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• 2011

The nucleophilic substitution reactions of dipropyl chlorothiophosphate (3) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $55.0^{\circ}C$. The obtained deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) are primary normal ($k_H/k_D$ = 1.11-1.35). A concerted mechanism involving predominant frontside nucleophilic attack is proposed on the basis of the primary normal DKIEs and selectivity parameters. Hydrogen bonded, four-center-type transition state is proposed. The steric effects of the two ligands on the anilinolysis rates of various substrates are discussed.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2306-2310
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• 2011

The nucleophilic substitution reactions of diethyl thiophosphinic chloride with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at 55.0 $^{\circ}C$. The values of deuterium kinetic isotope effects (DKIEs; $k_H/k_D$) invariably increase from secondary inverse ($k_H/k_D$ < 1) to primary normal (kH/kD > 1) as the nucleophiles change from the strongly basic to weakly basic anilines. The secondary inverse with the strongly basic anilines and primary normal DKIEs with the weakly basic anilines are rationalized by the gradual transition state (TS) variation from a predominant backside attack, via invariably increasing the fraction of a frontside attack, to a predominant frontside attack, in which the reaction mechanism is a concerted $S_N2$ pathway. A frontside attack involving a hydrogen bonded, four-center-type TS is substantiated by the primary normal DKIEs.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1016-1022
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• 2014

The kinetic studies on the reactions of O-methyl N,N-diisopropylamino phosphonochloridothioate with X-anilines and X-pyridines have been carried out in acetonitrile. The free energy relationship with X in the anilines exhibits biphasic concave upwards with a break region between X = (H and 4-F), giving unusual negative ${\beta}_X$ and positive ${\rho}_X$ values with weakly basic anilines. The unusual phenomenon is rationalized by isokinetic relationship. A stepwise mechanism with a rate-limiting leaving group departure from the intermediate is proposed based on the selectivity parameter and variation trend of the deuterium kinetic isotope effects with X. The free energy relationship with X in the pyridines exhibits biphasic concave upwards with a break point at X = 3-MeO. A concerted mechanism is proposed based on relatively small ${\beta}_X$ value, and frontside and backside nucleophilic attack are proposed with strongly and weakly basic pyridines, respectively.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1769-1773
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• 2008

fThe kinetics and mechanism of the reactions of Y-O-aryl phenylphosphonochloridothioates with X-pyridines are investigated in acetonitrile at 35.0 ${^{\circ}C}$. The negative value of the cross-interaction constant, $\rho$XY = −0.46, indicates that the reaction proceeds by concerted $S_N2$ mechanism. The observed $k_H/k_D$ values involving d-5 pyridine ($C_5D_5N$) nucleophiles are greater than unity (1.05-1.11). The net primary deuterium kinetic isotope effects, $(k_H/k_D)_{net}$ = 1.28-1.35, excluding the increased $pK_a$ effect of d-5 pyridine are obtained. The transition state with a hydrogen bond between the leaving group Cl and the hydrogen (deuterium) atom in the C-H(D) is suggested for the studied reaction system.

• 대한화학회지
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• 제62권4호
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• pp.265-268
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• 2018

The solvolyses of anthraquinone-2-carbonyl chloride (1) were studied kinetically in 27 pure and various mixed solvents. The analysis using the extended Grunwald-Winstein equation in the solvolyses of anthraquinone-2-carbonyl chloride (1) obtained the l value of $2.11{\pm}0.11$, the m value of $0.54{\pm}0.06$, and the correlation coefficient of 0.955. The solvolysis reaction of 1 might proceed via an associative $S_N2$ mechanism enhancing bond making than bond breaking in the transition state (TS). This interpretation is further supported by a relatively large solvent kinetic isotope effect (SKIE, 2.27).

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.936-940
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• 2007

The aminolyses of diphenyl phosphinic chloride (1) with substituted anilines in acetonitrile at 55.0 oC are investigated kinetically. Large Hammett ρ X (ρnuc = ?4.78) and Bronsted β X (βnuc = 1.69) values suggest extensive bond formation in the transition state. The primary normal kinetic isotope effects (kH/kD = 1.42-1.82) involving deuterated aniline (XC6H4ND2) nucleophiles indicate that hydrogen bonding results in partial deprotonation of the aniline nucleophile in the rate-limiting step. The faster rate of diphenyl phosphinic chloride (1) than diphenyl chlorophosphate (2) is rationalized by the large proportion of a frontside attack in the reaction of 1. These results are consistent with a concerted mechanism involving a partial frontside nucleophilic attack through a hydrogen-bonded, four-center type transition state.