|
KMID : 1024520100190050565
|
|
Journal of the Environmental Sciences
2010 Volume.19 No. 5 p.565 ~ p.575
|
|
|
Nucleophilic Effect of Alkylbenzimidazole and Micellar Effect of Cetylpyridinium chloride(CPyCl) on Dephosphorylation of Diphenyl-4-nitrophenylphosphinate(DPNPIN)
|
|
Kim Jeung-Bea
Kim Hak-Yoon
|
|
|
Abstract
|
|
|
|
This study is mainly focused on micellar effect of cetylpyridinium chloride(CPyCl) solution including alkyl- benzimidazole(R-BI) on dephosphorylation of diphenyl-4-nitrophenylphosphinate(DPNPIN) in carbonate buffer(pH 10.7). The reactions of DPNPIN with R-BI? are strongly catalyzed by the micelles of CPyCl. Dephosphorylation of DPNPIN is accelerated by BI? ion in 10-2 M carbonate buffer(pH 10.7) of 4×10-3 M CPyCl solution up to 100 times as compared with the reaction in carbonate buffer by no BI solution of 4×10-3 M CPyCl. The value of pseudo first order rate constant(kmBI) of the reaction in CPyCl solution reached a maximum rate constant increasing micelle concentration. Such rate maxima are typical of micellar catalyzed bimolecular reactions. The reaction mediated by R-BI? in micellar solutions are obviously slower than those by BI?, and the reaction rate were decreased with increase of lengths of alkyl groups. It seems due to steric effect of alkyl groups of R-BI? in Stern layer of micellar solution. The surfactant reagent, cetylpyridinium chloride(CPyCl) , strongly catalyzes the reaction of diphenyl-4-nitrophenylphosphinate(DPNPIN) with alkylbenzimidazole (R-BI) and its anion(R-BI?) in carbonate buffer(pH 10.7). For example, 4×10-3 M CPyCl in 1×10-4 M BI solution increase the rate constant (kψ=1.0×10-2 sec-1) of the dephosphorylation by a factor ca.14, when compared with reaction (kψ=7.3×10-4 sec-1) in 1×10-4 M BI solution(without CPyCl). And no CPyCl solution, in 1×10-4 M BI solution increase the rate constant (kψ=7.3×10-4 sec-1) of the dephosphorylation by a factor ca.36, when compared with reaction (kψ=2.0×10-5 sec-1) in water solution(without BI). This predicts that the reactivities of R-BI? in the micellar pseudophase are much smaller than that of BI? . Due to the hydrophobicity and steric effect of alkyl group substituents, these groups would penetrate into the core of the micelle for stabilization by van der Waals interaction with long alkyl groups of CPyCl.
|
|
|
KEYWORD
|
|
|
CPyCl, Micellar effect, Alkylbenzimidazole, Dephosphorylation
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|