Cationic surfactants quaternary alkyl ammonium

Fig. 2.12.8. FIA-APCI-MS-MS(—) (CID) product ion mass spectrum of a selected [M — H] parent ion (mlz 583) of cationic fluorinated quaternary alkyl ammonium surfactant blend (general formula CnF2n+i- S02-NH-CH2-CH2-CH2-N (CH3)3 x ...

Cationic surfactants (quaternary ammonium group) and amphoteric surfactants with a long alkyl chain present a poor absorption in UV. 

Ion flotation in the presence of surfactants for the treatment of rinses and separation of metal ions is of interest since the sixties [327, 328]. Here, we take only a few examples. The recovery of silver ions from highly diluted solutions is possible by forming a silver-thiourea complex in form of a colloidal precipitate (sublate) followed by sublate flotation with sodium dodecyl benzene sulfonate [329]. Skiylev [330] has developed methods for the removal of non-ferrous metal salts from waste waters. Subject of the investigations were 0.01 - 0.001% solutions of ferrous metal salts. Typical anionic surfactants (alkyl sulfates, alkyl phosphates, alkyl xanthogenates of potassium) or cationic surfactants (quaternary ammonium salts) were used as collectors in ion flotation from diluted solutions. At certain pH, a sublate containing a non-ferrous metal ion was formed, followed by a sublate film formation at the surface due to the rise of the complexes with air bubbles stabilised by the surfactants. 

Cationic Surfactants Quaternary ammonium cationic surfactants with alkyl groups of Ci6 to C22 with organic counterions have been smdied extensively [Chou, 1989b] and have been shown to be effective at concentrations as low as 50 ppm [Kawaguchi et al., 2003]. This effectiveness is enhanced by increasing the surfactant concentration and by increasing the counterion/cation ratio, f. 

Cationic surfactants, characterized by their amphiphilic properties, contain an alkyl hydrophobe and a hydrophilic positively charged head-group. Among cationic surfactants, quaternary ammonium salts are notable for their ability to reduce surface and interfacial tensions by ready adsorption to a surface or interface, such as hair and skin. This ability to adsorb on to substrates makes the use of cationic surfactants extremely important in the personal care industry. 

Cationic surfactants, characterized by their amphiphilic properties, contain an alkyl hydrophobe and a hydrophilic positively charged head group. Among cationic surfactants, quaternary ammonium salts are notable for... 

Two-dimensional LC to determine anionic surfactants (types of carboxylates, sulfates and sulfonates), cationic surfactants (quaternary ammonium and alkyl pyridinium salts) and amphoteric surfactants (amidobetaines) was proposed by Noguchi et al. (1998). First column (anion exchange column for anionics and cation exchange column for cationic and amphoteric surfactants) separated according to functional group and a second column (octadecylsilica) allowed the separation of alkyl homologues. The method was applied to shampoo. 

Higher order aUphatic quaternary compounds, where one of the alkyl groups contains - 10 carbon atoms, exhibit surface-active properties (167). These compounds compose a subclass of a more general class of compounds known as cationic surfactants (qv). These have physical properties such as substantivity and aggregation ia polar media (168) that give rise to many practical appHcations. In some cases the ammonium compounds are referred to as iaverse soaps because the charge on the organic portion of the molecule is cationic rather than anionic. 

Cationic, anionic, and amphoteric surfactants derive thek water solubiUty from thek ionic charge, whereas the nonionic hydrophile derives its water solubihty from highly polar terminal hydroxyl groups. Cationic surfactants perform well in polar substrates like styrenics and polyurethane. Examples of cationic surfactants ate quaternary ammonium chlorides, quaternary ammonium methosulfates, and quaternary ammonium nitrates (see QuARTERNARY AMMONIUM compounds). Anionic surfactants work well in PVC and styrenics. Examples of anionic surfactants ate fatty phosphate esters and alkyl sulfonates. 

Cationic surfactants are surface-active agents that have one or more functional groups in their molecule that ionise in aqueous solution to produce positively charged organic ions. The most representative cationic surfactants are quaternary ammonium derivatives in which the N atom is bonded to four alkyl groups. For many years, ditallow dimethylammonium chloride (DTDMAC) has been the most widely used product of this family. Its recalcitrance to biodegradation, however, has... 

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.

Quaternary fluorinated alkyl ammonium compounds The fluorine-containing cationic surfactants of quat type with the general formula C F2 , 1-S02-NH-CH2-CH2-CH2-N (CH3)3 X (n = 8) (Fig. 2.12.1(d)) were examined by FIA—MS using APCI and ESI in the positive and negative modes. The APCI(- -/—) ionisation resulted in a dealkylation at the nitrogen with ions at m/z 585 or 583, respectively. The alkyl chain of this compound contained the moiety C8Fi7. The ions generated under APCI conditions were characterised as dealkylation products—m/z 585 [M — CH2]+ or m/z 583 [M — H— CH3] —as reported in the literature [35,37]. 

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. 

Gas hydrate inhibitors. Gas hydrates, solid water clathrates containing small hydrocarbons, are problematic for oil and gas production because they can precipitate and cause line blockage. Simple cationic surfactants containing at least two butyl groups were previously developed to inhibit formation of gas hydrate precipitates in gas production lines [87]. However, similar to the situation with cationic drag reduction additives, poor toxicity profiles prevent widespread commercial acceptance. Ester quaternaries with structures somewhat similar to those used in fabric care have been claimed as hydrate inhibitors [88 ]. Additionally, certain alkylether quaternary compounds, e.g. C12-C14 alkyl polyethoxy oxypropyl tributyl ammonium bromide, were shown to have hydrate inhibition properties [89]. 

Cationic surfactants, where the hydrophilic group carries a positive charge (e.g., quaternary ammonium halides, R4N" C1 ). Examples of pharmaceutical importance include cetrimide, a mixture consisting mainly of tetradecyl (ca. 68%), dodecyl (ca. 22%), and hexadecyltri-methylammonium bromides (ca. 7%), as well as benzalkonium chloride, a mixture of alkyl-benzyldimethylammonium chlorides of the general formula [C6H5CH2N+(CH3)2R]C1, where R represents a mixture of the alkyls from... 

U.S. 5100657 (1992) Ansher-Jackson et al. (Procter Gamble) A mixture of conditioning agents silicone, cationic surfactant, and fatty alcohol nonionic long-chain alkylated cellulose ether as the primary thickener water-insoluble surfactant as a secondary thickener Provide cleaner hair conditioning does not have the dirty hair feel and quick resoiling of hair associated with quaternary ammonium... 

Furthermore, for some cationic surfactants, quantitative structure-activity relationships have been established for daphnids and fish. Increments used in the ECOSAR toxicity estimation software (Syracuse Research Center, freely available from the US Environmental Protection Agency as part of the software EPI Suite) are -0.13 and -0.37 for each carbon atom in monoalkyl quaternary ammonium surfactants in daphnids and fish, respectively. These increments are much smaller than the ones found here. Our increments for the n-alkyl chain in Rj position are more in accordance with increments for CH2 groups in n-octanol/water partitioning constant estimation procedures, which are, e.g., 0.66 and 0.49 in Hansch and Leo s method and Meylan and Howard s method, respectively [20]. This suggests that uptake into the cells is governed by lipophilicity, or maybe more exactly by membrane/water partitioning [21, 22]. 

Horiuchi, T., Yoshii, T., Majima, T., Tamura, T., and Sugawara, H., Effect of alkyl chain length and number of 2-hydroxyethyl groups on drag reduction behaviors of quaternary ammonium salt-type cationic surfactant solutions, Nippon Kagaku Kaishi, 415-421 (2001b). 

In cationic surfactants, the presence of short-chain alkyl groups (fewer than four carbon atoms) attached to the nitrogen seem to have little effect on the efficiency of adsorption of the molecule. The dominant factor will always be the length of the primary hydrophobic chain. That effect is true regardless of whether the alkyl groups are attached to a quaternary ammonium group, an amine oxide, or a heterocyclic nucleus such as pyridine. 

Cationic surfactants fall into several categories depending on the nature of their cationic polar heads. Some of them have functional groups susceptible to protonation e.g. amines) and thus display cationic properties particularly in acidic media, while others, such as quaternary ammonium salts, exhibit a permanent positive charge. In household products, cationic surfactants are primarily applied in fabric softeners and hair preparations. Other applications of cationic surfactants include disinfectants and biocides, emulsifiers, wetting agents and processing additives. By volume, the most important cationic surfactants in household products are the alkyl ester ammonium salts that... 

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