Ionic Liquids In Organic Synthesis

Two acidic ionic liquids, [Hmim][HSO₄] and [Hmim][CF₃COO] were synthesized, their acidity were measured by using PH indicator. The structure of the novel acidic ionic liquid [Hmim][HSO₄] has been identified by IR, ¹H NMR and HRMS. Alkyl benzenes and halo benzenes were nitrated with TFAA-NH₄NO₃ as nitrating reagent in the two acidic ionic liquids as solvents and catalysts. Nitration of halo benzenes in the acidic ionic liquids gave higher para isomer selectivity in reasonable yields compared to that obtained in mixed acid nitration. The acidic ionic liquids could be reused. Nitration of hexamine with TFAA-NH₄NO₃ in ionic liquids gave six memberd nitration product 1,3,5-trinitro-1,3,5-triazahexane, no eight memberd nitration product 1,3,5,7-tetranitro-1,3,5,7-tetraazaoctane was detected. Using the more acidic ionic liquid [Hmim][HSO₄] as dual solvent-catalyst, a serious of alkyl acetate have been prepared in yields ,Ccomparable to that obtained by concentrated sulfuric acid catalyzed esterification. The esterification in the ionic liquid was environmentally benign and with promising prospect in practical application.The task-specific ionic liquid, [H₃N-CH₂-CH₂-OH][CH₃COO], was synthesized and used as a novel catalyst in the Knoevenagel condensation of aromatic aldehydes with active methylene compounds. Reasonable yields of α,β-unsaturated carbonyl compounds were obtained and only E-alkenes were detected when the reactions were carried out at room temperature for several to sixty minutes under solvent-free condition. This process could be used in the industry.