Group 1 cations, solubility

Cationic, anionic, and amphoteric surfactants derive their water solubility from their ionic charge, whereas the nonionic hydrophile derives its water solubility from highly polar terminal hydroxyl groups. Cationic surfactants perform well in polar substrates like styrenics and polyurethane. Examples of cationic surfactants are 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 are fatty phosphate esters and alkyl sulfonates. 

Cationic functional group Specific solubility Specific conductivity (tnSg tntnor )... 

A selection of important anionic surfactants is displayed in table C2.3.1. Carboxylic acid salts or tire soaps are tire best known anionic surfactants. These materials were originally derived from animal fats by saponification. The ionized carboxyl group provides tire anionic charge. Examples witlr hydrocarbon chains of fewer tlran ten carbon atoms are too soluble and tliose witlr chains longer tlran 20 carbon atoms are too insoluble to be useful in aqueous applications. They may be prepared witlr cations otlrer tlran sodium. 

Quats are usually moderately soluble ia water, but this varies widely owiag to the range of groups bonded to the nitrogen. They are fundamentally nonreactive but act as surface—active cations. Compatibility with anionic detergents and activity ia the presence of hard water have been claimed for some quats (19). 

Polyethers. Antibiotics within this family contain a number of cycHc ether and ketal units and have a carboxyHc acid group. They form complexes with mono- and divalent cations that ate soluble ia aoapolar organic solvents. They iateract with bacterial cell membranes and allow cations to pass through the membranes causiag cell death. Because of this property they have been classified as ionophores. Monensia, lasalocid, and maduramicia are examples of polyethers that are used commercially as anticoccidial agents ia poultry and as growth promotants ia mmiaants. 

Microscopic sheets of amorphous silica have been prepared in the laboratory by either (/) hydrolysis of gaseous SiCl or SiF to form monosilicic acid [10193-36-9] (orthosihcic acid), Si(OH)4, with simultaneous polymerisation in water of the monosilicic acid that is formed (7) (2) freesing of colloidal silica or polysilicic acid (8—10) (J) hydrolysis of HSiCl in ether, followed by solvent evaporation (11) or (4) coagulation of silica in the presence of cationic surfactants (12). Amorphous silica fibers are prepared by drying thin films of sols or oxidising silicon monoxide (13). Hydrated amorphous silica differs in solubility from anhydrous or surface-hydrated amorphous sdica forms (1) in that the former is generally stable up to 60°C, and water is not lost by evaporation at room temperature. Hydrated sdica gel can be prepared by reaction of hydrated sodium siUcate crystals and anhydrous acid, followed by polymerisation of the monosilicic acid that is formed into a dense state (14). This process can result in a water content of approximately one molecule of H2O for each sdanol group present. 

ACID DYES Commercial acid dyes contain one or more sulfonate groups, thereby providing solubility in aqueous media. These dyes are apphed in the presence of organic or mineral acids (pH 2—6). Such acids protonate any available cationic sites on the fiber, thereby making possible bonding between the fiber and the anionic dye molecule. Wool, an animal fiber, is an amphoteric coUoid, possessing both basic and acidic properties because of the amino and carboxylic groups of the protein stmcture. In order to dye such a system, coulombic interactions between the dye molecule and the fiber must take place ie, H2N" -wool-COO + H2N" -wool-COOH. The term acid dye is appHed to those that are capable of such interactions. Acid dyes... 

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