2-Methyltetrahydrofuran (MeTHF) is a safe, environmentally friendly, and cost-effective alternative to tetrahydrofuran (THF), diethyl ether, and dichloromethane (DCM). MeTHF is commercially available from Penn A Kem, LLC. It is made from renewable resources by intramolecular cyclization of pentoses and hydrogentation.
MeTHF advantages stem equally form its physical and chemical properties: MeTHF is like THF in terms of chemical properties but resembles toluene in terms of physical properties. These advantages help reduce specific solvent consumption, carbon dioxide/VOC emissions, and energy.
The advantages of MeTHF versus THF in terms of physical properties are: • Rapid separation of two phases on work-up: avoids addition of toluene, formation of persistent milky emulsions/rag layers and wasted plant time. • Improved extraction yield: less wasted active material in water phase and less solvent. • Easy azeotropic drying at atmospheric pressure: dried azeotropically through simple distillation to yield product in a dry solution without isolation. • Easy solvent recycling: no need to fractionally distill mix of solvents or use complex recovery and drying in set of columns at different pressures.
The advantages of MeTHF versus THF in terms of chemical properties: • Higher reaction yields: e.g benzyl organogrignard 20% yield increase. • Higher stability to basic conditions: e.g. stability to n-BuLi improved by a factor of seven. • Higher stability to acidic conditions: e.g. stability to aqueous protic acids improved more than six times during work-up. • Smaller reactor volumes: MeTHF has excellent solvent properties allowing for highly concentrated solutions of some organometallic reagents. • Elimination of excess reagents: e.g. eliminates the need for excess magnesium in difficult organogrignard reactions.
Conclusion: MeTHF reduces the environmental footprint and production costs. This is why global companies are setting up programs to replace the use of the more traditional solvents with MeTHF.