Lanzhou Greenchem ILs (Center for Greenchemistry and catalysis), LICP, CAS. Ionic Liquids

BASF is pursuing ionic liquids in many different directions: another that is under development is ‘‘nucleophilic HCl’’.

QUILL showed that hydrogen chloride can act as a chlorinating agent towards arenes, generating chloroarenes. In a parallel development, BASF demonstrated that hydrogen chloride in ionic liquids can act as a phosgene substitute. The reaction of butan-1,4-diol with phosgene85 generates 1,4-dichlorobutane in essentially quantitative yield:

If the reaction is attempted with hydrogen chloride instead of phosgene, four products are formed, and the desired 1,4-dichlorobutane is only a minor by-product, the major products being tetrahydrofuran and 1-chlorobutan-4-ol: However, if the hydrogen chloride is dissolved in an ionic liquid, then almost pure 1,4-dichlorobutane is obtained (98% selectivity).