Tetrabutylphosphonium amino acids

Absorption of C02 at ambient pressure using basic ILs have attracted much attention in recent years, such as IL consisting of an imidazolium cation with a primary amine moiety and tetrafluoroborate anion [3], tetrabutylphosphonium amino acids [73]. Chitin and chitosan can be dissolved in [BMIm]Cl [74] and so on. 

Recently, ionic liquids with amino acids as anions were synthesized by neutralization between [C2mim][OH] and amino acids [88], Tetrabutylphosphonium amino acids [P(C4)4][AA] were synthesized by the reaction of tetrabutylphosphonium hydroxide [P(C4)4][OH] with amino acids, including glycine, L-alanine, l-/1-alanine, L-serine and L-lysine [89], The esters or amide derivatives of bromoacetic acid were either commercially available or formed in one step via the reaction of bromoacetyl bromide with the appropriate alcohol or amine [90-92], An advantage of this route is that a wide range of ester and amide side chains can be prepared easily. For ionic liquids with anions other than bromide, a metathesis reaction was employed to introduce the counter ion of choice. Additionally, functionalized ionic liquids with electrophilic alkene-type appendages were synthesized. 

Zhang J, Zhang S, Dong K, et al Supported absorption of CO2 by tetrabutylphosphonium amino acid ionic hquids, Chem Eur J 12 4021—4026, 2006. 

Field for Molecular Simulation of Tetrabutylphosphonium Amino Acid Ionic Liquids. 

Amino acids (AA), as one of the most abundant biomaterials in nature, are known to be nontoxic, biodegradable, and biocompatible. They are excellent feedstocks for the synthesis of ILs, because of their reasonable cost and environment-friendly characteristics. In 2005, a group of amino acid ionic liquids (AAILs) was first synthesized by Fukumoto s group from 20 natural AA [85]. They prepared AAILs based on l-ethyl-3-methylimidazolium cation, [emim], by neutralization method. In this method, [emim]OH was prepared by anion exchange resin, followed by addition of [emim]OH to a slight excess of an equimolar AA aqueous solution to prepare salts and water as a by-product [86]. Further, they synthesized tetrabutylphosphonium-based AAILs ([TBP][AA]) by mixing AA with aqueous solution of tetrabutylphosphonium hydroxide ([TBP][OH]) [87]. Tao et al. [88] synthesized [AAE]N03 ILs ([AAE] stands for AA ester as cation and NO3 stands... 

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