Synthesis of DBU-based ionic liquids as the novel and green catalysts and use them in the synthesis of 1H-pyrazolo [1, 2-b] phthalazine-5, 10-diones under solvent‐free conditions

Ionic liquids (ILs) are a fascinating class of low melting salts that generally are composed of large unsymmetrical organic cation and a weakly-coordinating inorganic or organic anion.1,2 At first, we synthesized two aprotic ionic liquids composed of 1,8-diazobicyclo [5.4.0] undec-7-ene-8-benzylium ([Bn-DBU]+) cation and [CH3CO2]− and [CF3CO2]− anions and characterized experimentally by the combined of 1HNMR and FTIR spectroscopies, and thermogravimetric analysis (TGA).The study of the various properties of N-substituted DBU-based ILs proved the advantages and uniqueness of these ILs as catalyst in different organic reactions.3,4 In the following, we use the [Bn-DBU][Y1-2], (Y = CH3CO2 and CF3CO2) ILs as catalyst in synthesis of 1H-pyrazolo [1, 2-b] phthalazine-5, 10-diones from reaction phthalhydrazid, aromatic aldehyde and malononitrile under solvent free condition at 100 °C.

Keywords:

Ionic liquid , 1 , 8-diazobicyclo [5.4.0] undec-7-ene-8-benzylium , 1HNMR , FTIR