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Nuclear magnetic resonance studies on hydrolysis kinetics and micellar growth in solutions of surface‐active betaine esters
Author(s) -
Lundberg Dan,
Holmberg Krister
Publication year - 2004
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-004-0307-9
Subject(s) - chemistry , hydrolysis , betaine , micellar solutions , dodecanol , micelle , organic chemistry , catalysis , kinetics , proton nmr , critical micelle concentration , aqueous solution , physics , quantum mechanics
Abstract A series of surface‐active betaine esters of medium‐ to long‐chain alcohols has been synthesized. The hydrophobic parts used were decyl, dodecyl, tetradecyl, and oleyl chains. Ethyl betainate was prepared as a non‐surface‐active reference compound. The surfactants were characterized by critical micellization concentration (CMC), and base‐catalyzed hydrolysis was studied by using 1 H nuclear magnetic resonance (NMR). Micellar catalysis was shown to have a strong influence on the hydrolysis. This means that the hydrolysis rates are concentration dependent. For dodecyl betainate, the effect of the degradation products (dodecanol and betaine) on the micellar shape was investigated by NMR diffusion experiments. The degradation products were shown to induce micellar growth.