Facilitated solvent screening for membrane-based extraction of chiral amines via a priori simulations

Chiral amines are important building blocks in the pharmaceutical industry. A challenge for the current industry is their difficult synthesis procedures, which employ harsh operating conditions or have an unfa-vourable equilibrium constant. An interesting strategy in improving the reaction equilibrium is the use of in-situ product removal via membrane extraction (ME) using supported liquid membranes (SLM), which is explored in this work. More specifically, the separation of the product amines a-methylbenzylamine (MBA) and 1-methyl-3-phenylpropylamine (MPPA) from the donor amine isopropyl amine (IPA) by employing SLMs is investigated in this study. A difficulty in SLM-applications is the solvent selection, which mostly requires the use of extensive liquid-liquid extraction (LLE) testing. In this work, COSMO-RS is used to perform a fast and simplified screening of almost 400 ILs, which led to a shortlist definition of fourteen ILs. For these fourteen ILs, critical solvent properties (i.e., density, viscosity and phase misci-bility) were analysed experimentally and compared to simulations in COSMO-RS. Finally, four promising ionic liquids were selected for further LLE-and ME-testing, namely trihexyltetradecylphosphonium bis (trifluoromethylsulfonyl)imide ([P6,6,6,14][N(Tf)2]), 1-methyl-1-propylpyrro-lidinium bis(trifluorome thylsulfonyl)imide ([C3mPyr][N(Tf)2]), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6mim][N(Tf)2]) and triethylsulfonium bis(trifluoromethylsulfonyl)imide ([S2,2,2][N(Tf)2]). Based on wettability testing of four polymeric porous substrates (i.e., PTFE, PES, PSf and PVDF), the PTFE-support was chosen for the stability tests, due to its very high hydrophobicity. The LLE-and stability tests showed that [P6,6,6,14][N(Tf)2] has the highest MBA/IPA-and MPPA/IPA-selectivity and the best SLM-stability of all the tested ILs. Comparative SLM-testing with the benchmarking solvent undecane showed that the IL [P6,6,6,14][N(Tf)2] has a higher SLM-selectivity than undecane at elevated temperatures, while no decrease in its stability was observed. (c) 2023 Elsevier B.V. All rights reserved.