(121c) A Scalable Membrane Pervaporation Approach for Continuous Flow Ring Closing Metathesis

Authors: 
Murnen, H., Compact Membrane Systems
Bio, M., Snapdragon Chemistry
Shangguan, N., Compact Membrane Systems
Majumdar, S., Compact Membrane Systems
Parrish, C., Compact Membrane Systems
Breen, C. P., Massachusetts Institute of Technology
Jamison, T., Massachusetts Institute of Technology
Pervaporation membranes can be used to avoid azeotropic distillation, enable flow chemistry technology, degas organic solvents, dehydrate solvents, drive reactions towards product formation, and more. Compact Membrane Systems (CMS) has demonstrated the effectiveness of their fluoropolymer pervaporation membranes to degas and dewater organic solvents for the pharmaceutical and specialty chemical industries in recent years. These membranes are applicable to a wide variety of solvents and operating conditions including difficult solvents such as NMP, DMSO or THF. In this talk, CMS will describe their newest pervaporation case study, performed in collaboration with Snapdragon Chemistry. A CMS membrane was used to selectively remove ethylene from a ring closing metathesis reaction in toluene to drive product formation and enable the use of flow chemistry.

Using traditional batch techniques, implementing olefin metathesis reactions on the commercial scale has proven challenging, if not impossible. Ring closing reaction mechanisms are commonly used during the preparation of small molecules for the pharmaceutical and fragrance industries. Membranes are a modular, scalable solution that can continuously remove the ethylene byproduct and enable the use of commercial scale continuous ring closing metathesis. This case study details the advantage of using a sheet-in-frame membrane reactor as opposed to a stainless steel tubular reactor. The fluoropolymer membrane has excellent chemical and thermal stability which allows for an extended range of thermal conditions without sacrificing selectivity or flux. Pure ethylene flux of the membrane was also investigated to ensure that the mass transport across the membrane would always be greater than the reaction’s ethylene production rate. Scale up considerations including residence time, required ethylene removal rate and module design will be addressed. The feasibility of using a membrane reactor to remove byproducts shown in this case study is only one example of the reactions that could benefit from the implementation of membrane reactors.