Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9675891 | Colloids and Surfaces A: Physicochemical and Engineering Aspects | 2005 | 4 Pages |
Abstract
Micellar-catalyzed alkaline hydrolysis of 2,4-dinitrochlorobenzene (DNCB) in the presence of a conventional cationic surfactant CTAB or a cationic gemini surfactant 1,2-ethane bis(dimethyldodecylammonium bromide) (12-2-12) were studied spectrophotometrically at 25 °C. It was found that both CTAB and 12-2-12 micelles accelerated the alkaline hydrolysis of DNCB, and the binding constant of the substrate to the micelle, KS, for 12-2-12 (KS = 310 Mâ1) was larger than that for CTAB (85 Mâ1), which suggested that DNCB molecules bound with gemini micelles more easily than with CTAB. However, the second-order rate constant in micellar pseudophase (kM = 1.22 Ã 10â3 sâ1) for 12-2-12 was lower than kM for CTAB (4.01 Ã 10â3 sâ1) because the substrate may enter the interior of the 12-2-12 micelles. It was found also that 12-2-12 had a similar catalysis mechanism to CTAB when the concentration of 12-2-12 was relatively low (ca. <5 mM). However, above this concentration, higher microviscosity and significant increases in aggregation number and micelle size with increased surfactant concentration may remarkably influence the hydrolysis reaction.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Colloid and Surface Chemistry
Authors
Ling-Guang Qiu, An-Jian Xie, Yu-Hua Shen,