Industrial & Engineering Chemistry Research, Vol.58, No.11, 4656-4666, 2019
Process Intensification Strategies and Sustainability Analysis for Amidation Processing in the Pharmaceutical Industry
The amidation reaction between 4-chlorobenzoyl chloride (CBC) and diisopropylamine (DIPA) has been successfully intensified with the implementation of a number of process intensification (PI) options proven feasible in lab-scale experiments. Three PI options are explored-an intensified batch case, a continuous reaction case, and a continuous whole-process case-and these are each compared to the batch base case. The PI options included reducing the amount of DIPA and solvents used in washes and carrying out continuous flow reaction in static mixers. A systematic series of washes and phase separation were also performed in a centrifugal extractor, which enabled a continuous extraction process to be developed. Promising experimental results were obtained using a wiped film evaporator (WFE) for continuous solvent removal. Plant designs were generated for the options at a hypothetical throughput of 3.3 t/year. Overall, the highest cost savings of up to 40% are estimated for the intensified batch case. In this particular process assumed to operate at 100% amide yield, the intensified batch is more suitable than continuous mode because the continuous options require a different mode of reagent addition resulting in a larger amount of water used to dissolve DIPA. However, if amide yield of 100% proves to be difficult to achieve in the intensified batch, the continuous reaction process scheme may become a more desirable option, as demonstrated by a sensitivity analysis.