Carboxylate anion, zwitterionic liquids

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Substitution of /7-dichlorobenzene by 185 was carried out in liquid ammonia/benzoni-trile in the presence of a mediator whose role is also to oxidize the anion radical of the monosubstitution product in order to decrease the degree of disubstitution258. The monosubstitution product (67%) was then further substituted to give a phosphine and (phosphoniophenyl)phenoxide zwitterions or was carboxylated to obtain 3, 5 -di- -butyl-4 -hydroxy-1,1 -biphenyl-4-carboxylic acid258. 

The other three cases are less common. In the case of chemically anchored anionic species, mostly carboxylate [78,79] or sulfonate groups have been investigated. Examples for chemically fixed cation/anion pairs are scarce here, ammonium carboxylate [80,81] or, more related to water-immiscible ionic liquids, guanidinium sulfonimide ion pairs [82] have been reported. The chemical grafting of zwitterionic species is nearly always related to immobilized ammonium or imidazolium sulfonate zwitterions that are easily formed upon reaction of nucleophiles (amines or imidazoles) with sultones [83-85]. 

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