Solvent-free flow synthesis of [OMIM]Br in a microreactor

Abstract

Solvent-free, continuous flow synthesis of [OMIM]Br in a microfluidic platform is reported for the first time. The microreactor comprises of a 862 µm diameter microbore tube attached to a 750 µm diameter opposed T-junction. Systematic experiments are conducted to study the effects of residence time, reaction temperature and flow velocity on product yield, space-time-yield, production rate and specific power consumption. An increase in residence time and reaction temperature is seen to increase product yield and production rate. At constant residence time, an increase in flow velocity is found to slightly increase product yield suggesting presence of mass transfer resistances at low velocities. Kinetic parameters of the alkylation reaction are determined. A pseudo first order kinetics is found to fit the experimental data better than second order kinetics. Frequency factor and activation energy for the pseudo first order reaction are found to be 3361.83 L/mol-s and 47964.76 J/mol, respectively. [OMIM]Br yield of 58.75 % can be achieved within 4.74 min residence time at 90°C. Under these conditions, the overall reaction is kinetically controlled (Ha being 0.004). Corresponding values of space-time-yield, production rate and specific power consumption are 119.15 g/min-L, 5284 g/day and 10.46 W/kg, respectively.