Synthesis Of Acidic Ionic Liquids And Their Catalytic Activities

Scientist’s urge to produce greener and more efficient catalysts have brought more pursuit for molten salts ionic liquids.Most catalysts in chemical industries such as H₂SO₄,hydrochloric acid are homogenous catalysts are utilized industrially having considerable drawbacks.On the other hand liquid catalysts either Br（?）nsted or Lewis acids based are convenient and more pollution free in chemical production.The main benefit of acidic ionic liquids have likewise other catalyst is the solubility of most compounds at high temperature.In addition the self-separation ability and easy recovery of acidic ionic liquids boost once more their net preference.Acid ionic liquids are quite easy to synthesize under standard conditions.This uniqueness is due to the presence of ionic liquid having either anions,cations or both.In order to improve the catalytic activities of acidic ionic liquid,our main concern here is to design and synthesize acidic ionic liquids with multi-functional active sites while maintaining their environmentally friendly properties.Three kinds of ionic liquids were presented;which includes:1.First,the Br（?）nsted SO₃H-（sulfonic group）acidic ionic liquids were prepared using Cyclopenta[b]pyridine.This was mixed with 1,4-butane sulfonate to produce zwitterions,which were later treated with sulphuric acid.When the catalysts were obtained,they were characterized by DRX-400 NMR spectroscope.The catalysts showed relatively high catalytic activity for the addition of amines to alkenes with a deficiency in electrons with yield up to 99%.The catalysts could be separated from the reaction mixture and reused after washing with ethyl acetate over 6 times.For Cyclopenta[b]pyridine based acidic ionic liquid catalyst,the catalytic activity was also tested for oxathioacetalization of carbonyl compounds giving yield up to 95%and the catalyst could be reused 5 times.2.The synthesis of Br（?）nsted-Lewis acidic ionic liquids with two kinds of acidic sites were carried out in the second work.The mixtures of both Lewis and Br（?）nsted acid sites increase considerably the catalytic activity of the catalyst in reaction media.Compared to other catalysts,this catalyst is air and water stable and this suitably meets up the environmental friendly requirements as it can operate in aqueous solution.The catalyst was prepared by mixing pyridine in equimolar amount with1,4-butane sulfonate for 72 h under mild conditions.The result was a white precipitate after washing with ether.Further the acidified zwitterion was deprotonated using Fe3+to introduce Lewis acidic sites.The catalytic activity of was investigated Michael addition reaction and acetalization of carbonyl compounds.The efficiency was over 90%and the catalyst recycled using ethyl acetate and ethyl ether both in and equimolar proportion and reused over 6 times.3.The synthesis of multi-SO₃H functionalized acid ionic liquid was investigated for reactions such as acetylation of alcohols,as well as phenols and amines as well as oxathioacetalization of carbonyl compounds in the third part.This catalyst is very efficient as it can have more SO₃H（double）functional group hence having move acid sites increasing its acidity and catalytic performance giving high yields.Furthermore the air and water stability of this catalyst is of great advantage for researchers as its large application in big scale reactions.The catalysts are prepared by mixing isoquinoline with 1,4-butane sulfonate for 72h at room temperature.A white zwitterion precipitate is obtained after been washed with ether and dried in vacuum dryer.Double molar H₂SO₄was mixed with the zwitterion for 4 h at 60°C to homogenize the mixture.Characterization of the catalyst was done by NMR spectroscopy.The catalytic activity was investigated using acetylation of phenols,amines and alcohol.The effectiveness of the activity was investigated by GC-MS analysis and the yield was over 90%and the catalyst was reused over 5 times.