Synthesis Of Quaternary Ammonium-Based Ionic Liquids And Its Application In The Reductive Amination Of The Carbonyl Compounds

Reductive amination of the carbonyl compounds is an important organic synthesis. There was always virulent and easy to volatilize solvent where the reductive amination reacted, along with precious metal and metal catalysis.The problems were the pollution of the environmental and the outflowing of the catalyst and so on. The ionic liquid has got merits such as low steam tension, strong capacity of dissolving, good thermostability and so on.It is getting more and more popular in the organic synthesis .At first a functionized ionic liquid N,N,N-tributyl-N-hydroxyethyl was synthesized. Different conditions of the synthesis by traditional heating and microwave heating were studied, both achieved a yeild of higher than 90%. Then the N,N,N-tributyl-N-hydroxyethyl reactied with sodium borohydride,achieved an ionic liquid 2-(tributylamino)-ethoxyborohydride (IL-OBH3) with an isolated yield of 72%. As a result of the electronegativity of the hydrogen connected with boron atom, this ionic liquid have a reducibility similar with the borane. Applied the reductive ionic liquid to the direct reductive amination of the carbonyl compounds and the amines as the ionic liquid take an identities of solvent,catalyst,reducing agent. The product of the amination was easy to separate and the ionic liquid was easy to recovery with no organic effluent,stable system,mild conditions,simple handling,high selectivity. It reduced the amount of the reducing agent so to reduce the toxicity greatly compared to other borohydride. Its performance did not deteriorate after several recovery and recycled. The results will be better with the existence of either methanol or the montmorillonite. Diffrent carbonyl compounds and amines have got a good yield between 44.7 %～97.5 % in different conditions.