|
KMID : 1024520080170050509
|
|
Journal of the Environmental Sciences
2008 Volume.17 No. 5 p.509 ~ p.516
|
|
|
Hydrolysis of p-Nitrophenyl Carboxylic Ester in N,N-Dimethyl-N-dodecyl-N-(2-methylbenzimidazoyl) Ammonium Chloride Micellar Solution
|
|
Kim Jeung-Bae
Kim Hak-Yoon
|
|
|
Abstract
|
|
|
|
New functional surfactant, N,N-dimethyl-N-dodecyl-N-(2-methyl benzimidazoyl) ammonium chloride(DDBAC) having benzimidazole(BI) functional group have been synthesized and the critical micellar concentration of DDBAC measured by surface tentiometry and electric conductivity method was . Micellar effects in DDBAC functional surfactant solution on the hydrolysis of p-nitrophenylacetate(p-NPA), p-nitro-phenylpropionate(p-NPP) and p-nitrophenylvalerate(p-NPV) were observed with change of various pH (Tris-buffer). The pseudo first rate constants of hydrolysis of p-NPA, p-NPP and p-NPV in optimum concentration of DDBAC solution increase to about 160, 280 and 600 times, respectively, as compared with those of aqueous solution at pH 8.00(Tris-buffer). It is considered that benzimidazole functional moiety accelerates the reaction rates of hydrolysis because they act as nucleophile or general base. In optimum concentration of DDBAC solution, the rate constants of hydrolysis of p-NPP and p-NPV increase to about 1.5 and 3.0 times, respectively, as compared with that of p-NPA. It means that the more the carbon numbers of alkyl group of substrates, the larger the binding constants between DDBAC micelle and substrates are. To know the hydrolysis mechanism of p-NPCE(p-NPA, p-NPP and p-NPV), the deuterium kinetic isotope effects were measured in solutions. Consequently the pseudo first order rate constant ratios in and solution, , were about range. It means that the mechanism of hydrolysis were proceeded by nucleophile and general base attack in approximately same value.
|
|
|
KEYWORD
|
|
|
Functional micelle, Hydrolysis, Benzimidazole, Deuterium kinetic isotope effect
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|