Catalytic hydrogenation of dimethyl itaconate in non-ionic microemulsions: influence of the size of micelle

Abstract

The structural dimensions of two different microemulsions were extracted and correlated with the catalytic hydrogenation of dimethyl itaconate (DMI) performed in such media using the water-soluble catalyst complex Rh–TPPTS. The commercial, polyoxyethylene-based non-ionic surfactants Igepal CA-520 and Triton X-100 were used to obtain two different types of microemulsions with cyclohexane and water; pentanol as a cosurfactant was added to the Triton system. Dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements were used to determine the characteristic sizes of the Igepal and Triton microemulsions, respectively, showing a linear dependence between the initial hydrogenation rate of DMI and the radius of the micelles. The initial hydrogenation rate of DMI in bulk water is exceeded in both microemulsions. Indications of deformation of the originally spherical Triton X-100 reverse micelles upon addition of the water-soluble catalyst complex Rh–TPPTS were found.