Gemini quats

Fig. 2.12.1. Chemical structure of different classes of cationic surfactants (a) quaternary ammonium surfactants (quats) (b) dialkylcarboxyethyl hydroxyethyl methyl ammonium surfactants (esterquats) (c) alkyl polyglycol amine surfactants (d) quaternary perfluoro-alkyl ammonium surfactants (e) N, N, N1, JV -tetramethyl-iV, iV -didodecyle-l,3-propane-diyle-diammonium dibromide (cationic gemini surfactant). R = alkyl or benzyl group.

Various classes of cationic surfactants, including quats, esterquats, alkyl ethoxy amines, quaternary perfluoroalkyl ammoniums and gemini surfactants have been analysed extensively with LC—MS and LC—MS—MS techniques, and their spectra have been fully characterised. Different ionisation methods have been applied for the detection of such surfactants, including API techniques (APCI and ESI) in negative and positive modes of operation. In addition, detailed examples regarding MS—MS fragmentation of these compounds have been reported and presented in this chapter. 

FIGURE 29.6 Modified xylyl bis-quat geminis synthesized by Brinchiet al. (Reproduced fromBrinchi, L., Germani, R., Goracci, L., Savelli, G., Bunton, C.A., Langmuir, 18, 7821—7825, 2002. With permission.)... 

FIGURE 29.7 Stilbenoid bis-quat gemini (where NBS—N-bromosuccinimide DEG—diethylene glycol) reported by Eastoe et al. (Reproduced from Eastoe, J., Sanchez Dominguez, M., Wyatt, R, Beeby, A., Heenan, R.K., Langmuir, 18, 7837-7844, 2002. With permission.)... 

A variety of gemini bis-quats with hydroxylated spacers have been reported by Logan [42] and Kim et al. [43-45] through an alternative alkylation route using epichlorohydrin. This epi-chlorohydrin method has been reported for versions incorporating ester and amide functionalities in the hydrophobic chains examples are shown in Figure 29.8. Ricci et al. [46] further reported a... 

FIGURE 29.24 Synthesis of bis-quat trehalose geminis. (Reproduced from Menger, F.M., Mbadugha, B.N.A., J. Am. Chem. Soc, 123, 875-885, 2001. With permission.)... 

The gemini-containing cationic [quaternary ammonium salts, called bis (Quats)], anionic (phosphate, sulfate, carboxylate), amphoteric and nonionic (polyether or sugar), polar groups have been a matter of numerous investigations [59]. Only few studies have been done on the physicochemical and biological properties of amino acid-based gemini surfactants [60-62]. 

Our group designed and synthesized a new elass of amino acid-based gemini surfactants of the bis(Quats) type (quaternary ammonium salt) (Scheme 2). These consist of 2 hydrophobic chains of 12 carbon atoms, 2 quaternary ammonium groups, and 1 spacer chain containing amide and disulfide bonds [63,64], They derived from the condensation of 7V-dodecyl-A, A -dimethylgly-cine (a well-known soft amphoteric surfactant) with amino acid derivatives containing disulfide bonds, i.e., cystine 1 and cystamine 2 (Scheme 2). 

SCHEME 2 Structures of bis(Quats) gemini cationic surfactants. 

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