Tandem micellar catalysis and cloud point extraction process for C-S coupling reaction in water

A tandem process of micellar catalysis and cloud point extraction (CPE) is developed for copper-catalyzed Ullmann C-S coupling reactions in water. The functional nonionic surfactant, amine terminated polyether M2070, affords nano-micelle environment in the aqueous system; the latter splits to two phases above the cloud point temperature (CPT). The nature of the micellar catalysis in M2070 aqueous was investigated by DLS, EDS, XPS, IR, TEM and 1 H NMR. M2070 was verified to provide nano-space for encapsulation and aggregation of the substrates. More importantly, the metallic micelle formed by M2070 chelating copper was identified. It is noteworthy that excellent productivity in pre-micellar catalysis of C-S coupling reactions was obtained with good tolerance of substrate. Finally, the water-micelle system was separated into two phases above the CPT thus to achieve the product separation. Furthermore, the M2070/water system can be recycled and reused.