Cyrene™ is a chiral dipolar aprotic solvent manufactured from renewable cellulose by Circa.
Developed in conjunction with University of York’s Green Chemistry group, Cyrene™ has successfully undergone initial testing across a range of, generic solvent reactions indicating it could be a viable alternative to NMP (NMP has been classified under REACH as toxic for reproduction). An Ames miniscreen test for potential mutagenicity has been completed with no mutagenicity observed.
Cyrene™ is similar to NMP in terms of its hydrogen bonding capacity (Kamlet-Taft solvatochromic scales). Accordingly Cyrene™ is a capable bio-based solvent substitute for heteroatom alkylation, fitting the linear solvation energy prominent in the pharmaceutical and other fine chemical industries, giving Cyrene™ an entry point as a solvent.
Fluorination is dependent on stabilising the Meisenheimer intermediate of the reaction but not deactivating the fluoride nucleophile. This can be fulfilled by Cyrene™ albeit with slower rates of reaction than dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) because of the underlying apparent dependence of the reaction rate on Reichardt polarity.
Overall Cyrene™ has all but matched the performance of NMP in both reaction case studies without exposing process workers and the environment to the same level of risk. Cyrene™ is surprisingly polar, and can be thought of as between sulfolane and NMP in terms of its hydrogen bonding capacity (Kamlet-Taft solvatochromic scales).