Study On The Properties And Stability Of Ionic Liquids

Green chemistry is to eliminate the pollution from the source origin, in the economic point of view, and to be able to use the resources and energy reasonably, reduces the production cost, is quite in accord with the requirement of sustainable development of economy.Some properties of ionic liquids(ILs), enable to obtain the considerable development in the green chemistry, which can be applied to the fields of the catalysis, separation, organic synthesis, preparation of materials, resources and environment.Quantum mechanics is the foundation of quantum chemical methods, which is a use of the basic principle and method of the quantum mechanics to solve the problem of chemistry subject. The calculation method of quantum chemistry are: ab initio method, semi empirical method and density functional theory methods.First, the most stable structures of the ion-pairs for the acetate-based protic ionic liquids(PILs) pyrrolidinium acetate([Pyrrol]OAc), diethylammonium acetate([DEA]OAc) and bis-(2-methoxyethyl)-ammmonium acetate([BMOEA]OAc) were optimized at B3LYP/6-311++G(d,p) level. The proton transfer processes are verified by intrinsic reaction coordinate(IRC) pathways. The transition state(TS) accounting for proton to transfer from [NH2]+ cation to OAc- anion is indicated by vibrational mode analyses(VMA), natural bond orbital(NBO) method and atoms in molecules theory(AIM) method.Second, The thermal stability of an amine–functionalized IL 1,2-dimethyl-(3-aminoethyl) imidazolium tetrafluoroborate [aEMMIM][BF4] is investigated by. B3LYP/6-311++G(d, p) level. The energies of reactant(R), intermediates(IM), transition state(TS) and product(P) are obtained and analyzed by vibrational mode analyses(VMA), [aEMMIM][BF4] follows unimolecular nucleophilic substitution(SN1) decomposition(98.8%), while SN2(bimolecular nucleophilic substitution) decomposition(1.2%) is unfavorable. The chemical nature of covalent bond and hydrogen bond is analyzed by the vibrational modes analysis(VMA), atoms in molecules(AIM) and theory of nature bond orbital(NBO).Third, hydrogen sulphide(H2S) is highly toxic and corrosive gas, the absorption of H2 S in ionic liquids [Bmim][PF6] and [Bmim][BF4] are investigated by B3LYP/6-311++G(d, p) level. The interaction energies and absorption mechanisms are analyzed by vibrational mode(VMA), natural bond orbital(NBO) and atoms in molecules theory(AIM) theory.