1-Butyl-2,3-dimethylimidazolium tetrafluoroborate (also named as BDMIMBF4) is a useful ionic liquid commonly used as green solvents in various applications, such as task-specific solvent for chemical transformations.
1-Butyl-2,3-dimethylimidazolium tetrafluoroborate: the most desirable ionic liquid solvent for recycling use of enzyme in lipase-catalyzed transesterification using vinyl acetate as acyl donor. 
The local structure of ionic liquids: cation-cation NOE interactions and internuclear distances in neat [BMIM][BF4] and [BDMIM][BF4]. 
 T.Itoh, et al, J. Mole. Catal. B Enzym., 2003, 26(1-2), pp 41-45.