Microemulsion and micellar aggregates as reaction media for preparing bisquaternary

: C.G. RICCI, M.I. CABRERA, J.A. LUNA, R.J.A. GRAU.

Fortaleza - Brasil

Congreso; 15 th Surfactants in Solution Symposium; 2004

UNESP. CNPq. fapesp. capes

Cationic dimeric surfactants continue to attract attention due to widespread applications and peculiar solution behavior. The development of fast and selective synthetic routes to dimeric surfactants under mild reaction conditions, avoiding the use of expensive solvents, is especially desirable for large -scale preparations. In this connection, the synthesis of bis-quaternary ammonium salts from long-chain tertiary amines and epihalohydrin assisted by the amine hydrochlorides proved to be advantageous in aqueous system [Ricci et al., 2002, 2003]. In contrast to alcoholic and hydroalcoholic quaternization, the bisquaternary ammonium salts were obtained in good yields (85-90%), even at low temperature (50oC). The micro emulsification and/or self-micellization of reactants were found to be key factors to enhance the rate of reaction without formation of the mono-quaternary ammonium salts as intermediates. In this work, photon correlation spectroscopy (PCS) and conductivity measurements are used to characterize the changes in the aggregation systems that take place during the kinetic runs, as consequence of the depletion of the amine hydrochlorides and formation of the dimeric surfactants, which have a greater ability to form micelles than their single-chain hydrochloride precursors. A plausible kinetic scheme is proposed for the aqueous quaternization system, which involves partitioning of these functional surfactants between the aqueous solution and aggregates, self-assembly between these surfactants and long-chain tertiary amines, and quaternization within a narrow region neighboring at the interface. It is argued that quaternization proceeds by a reaction path different from that proposed for homogeneous reaction systems. The kinetic data are discussed in terms of the complex and changing structure of the aggregates.bis-quaternary ammonium salts from long-chain tertiary amines and epihalohydrin assisted by the amine hydrochlorides proved to be advantageous in aqueous system [Ricci et al., 2002, 2003]. In contrast to alcoholic and hydroalcoholic quaternization, the bisquaternary ammonium salts were obtained in good yields (85-90%), even at low temperature (50oC). The micro emulsification and/or self-micellization of reactants were found to be key factors to enhance the rate of reaction without formation of the mono-quaternary ammonium salts as intermediates. In this work, photon correlation spectroscopy (PCS) and conductivity measurements are used to characterize the changes in the aggregation systems that take place during the kinetic runs, as consequence of the depletion of the amine hydrochlorides and formation of the dimeric surfactants, which have a greater ability to form micelles than their single-chain hydrochloride precursors. A plausible kinetic scheme is proposed for the aqueous quaternization system, which involves partitioning of these functional surfactants between the aqueous solution and aggregates, self-assembly between these surfactants and long-chain tertiary amines, and quaternization within a narrow region neighboring at the interface. It is argued that quaternization proceeds by a reaction path different from that proposed for homogeneous reaction systems. The kinetic data are discussed in terms of the complex and changing structure of the aggregates.bisquaternary ammonium salts were obtained in good yields (85-90%), even at low temperature (50oC). The micro emulsification and/or self-micellization of reactants were found to be key factors to enhance the rate of reaction without formation of the mono-quaternary ammonium salts as intermediates. In this work, photon correlation spectroscopy (PCS) and conductivity measurements are used to characterize the changes in the aggregation systems that take place during the kinetic runs, as consequence of the depletion of the amine hydrochlorides and formation of the dimeric surfactants, which have a greater ability to form micelles than their single-chain hydrochloride precursors. A plausible kinetic scheme is proposed for the aqueous quaternization system, which involves partitioning of these functional surfactants between the aqueous solution and aggregates, self-assembly between these surfactants and long-chain tertiary amines, and quaternization within a narrow region neighboring at the interface. It is argued that quaternization proceeds by a reaction path different from that proposed for homogeneous reaction systems. The kinetic data are discussed in terms of the complex and changing structure of the aggregates.oC). The micro emulsification and/or self-micellization of reactants were found to be key factors to enhance the rate of reaction without formation of the mono-quaternary ammonium salts as intermediates. In this work, photon correlation spectroscopy (PCS) and conductivity measurements are used to characterize the changes in the aggregation systems that take place during the kinetic runs, as consequence of the depletion of the amine hydrochlorides and formation of the dimeric surfactants, which have a greater ability to form micelles than their single-chain hydrochloride precursors. A plausible kinetic scheme is proposed for the aqueous quaternization system, which involves partitioning of these functional surfactants between the aqueous solution and aggregates, self-assembly between these surfactants and long-chain tertiary amines, and quaternization within a narrow region neighboring at the interface. It is argued that quaternization proceeds by a reaction path different from that proposed for homogeneous reaction systems. The kinetic data are discussed in terms of the complex and changing structure of the aggregates.mono-quaternary ammonium salts as intermediates. In this work, photon correlation spectroscopy (PCS) and conductivity measurements are used to characterize the changes in the aggregation systems that take place during the kinetic runs, as consequence of the depletion of the amine hydrochlorides and formation of the dimeric surfactants, which have a greater ability to form micelles than their single-chain hydrochloride precursors. A plausible kinetic scheme is proposed for the aqueous quaternization system, which involves partitioning of these functional surfactants between the aqueous solution and aggregates, self-assembly between these surfactants and long-chain tertiary amines, and quaternization within a narrow region neighboring at the interface. It is argued that quaternization proceeds by a reaction path different from that proposed for homogeneous reaction systems. The kinetic data are discussed in terms of the complex and changing structure of the aggregates.