A Metal- and Solvent-Free Synthesis of aminoalcohols under Continuous Flow Conditions
The use of multifunctional organocatalysts and continuous flow platform are commonplace in modern chemical transformation. Herein, we describe a method for immobilization of trifunctional organocatalysts on porous composite hollow fiber and demonstrate their application as heterogeneous catalyst and continuous-flow microfluidic reactor for chemical transformation. The polyamide imide hollow fibers (PAIHF’s) are functionalized with aminosilanes and bromine source to immobilize covalently hydrogen-bond donor groups (-OH and -NH), and nucleophilic [Br−] species upon the fiber surface and provide trifunctional acid-base-nucleophilic organocatalysts and microfluidic reactors. The cooperative effects of Br/APS/PAIHF trifunctional organocatalysts are elucidated in the CO2 cycloaddition and hydroxyalkylation of aniline under batch and continuous flow synthesis. Our results indicated that the synergistic cooperative effect of trifunctional organocatalyst on PAIHF leads to a maximum 1-(phenylamino)propan-2-ol selectivity of 97.1% at 61% aniline conversion and 0.02 cm3/min flow rate. While knowledge of the acid-base-nucleophilic trifunctional cooperativity is still limited, these findings demonstrate useful structure-property trends that can be used to design more efficient organocatalysts for sustainable chemical transformation.