Cetylpyridinium halide

EXPERIMENTAL PROCEDURES AUTOMATED TURBIDIMETRIC TITRATION. A method for the automated aqueous turbidimetric titration of surfactants has been published (10) in which anionic surfactants are titrated against N-cetylpyridinium chloride to form a colloidal precipitate near the equivalence point. N-cetylpyridinium halides have a disadvantage in that they have the tendency to crystallise out of solution (15), consequently the strength of the solution may alter slightly without the knowledge of the operator, also the crystals suspended in solution may cause damage to the autotitrator. In view of these drawbacks hyamine was preferred as the titrant. 

Quaternary ammonium compounds Alkylisoquinolinium bromide Cetylpyridinium halides... 

Using distribution between chloroform and water, Jones and asso-ciates have separated an acetylated mixture of neutral polysaccharide, which dissolved in the chloroform, and an acidic polysaccharide, which formed an emulsion between the two phases. Such mixtures were shown by Scott < to be easily separated by precipitation of the acidic component with such quaternary ammonium salts as cetyltrimethylammonium (Cetavlon) or cetylpyridinium halides. Polysaccharides which differ in acidity can also be separated by this method, and, as the solubility of the precipitate increases with increasing ionic strength, the separation can also be done as... 

Heteroaromatic ammonium salts (one R stands for a long-chain alkyl group, and the remaining three R are components of an aromatic system such as pyridine, quinoline or isoquinoline), e.g. cetylpyridinium halide and alkylisoquinolinium bromide. 

Ishii, Y., Yamawaki, K., Ura, T., et al. (1988). Hydrogen Peroxide Oxidation Catalyzed by Heteropoly Acids Combined with Cetylpyridinium Chloride. Epoxidation of Olefins And Allylic Alcohols, Ketonization of Alcohols and Diols, and Oxidative Cleavage of 1,2-Diols and Olefins, J. Org. Chem., 53, pp. 3587-3593 Sato, K., Aoki, M., Ogawa, M., et al. (1997). A Halide-Free Method for Olefin Epoxidation with 30% Hydrogen Peroxide, Bull. Chem. Soc. Jpn., 70, pp. 905-915 Xi, Z. W., Zhou, N., Sun, Y., et al. (2001). Reaction-Controlled Phase-Transfer Catalysis for Propylene Epoxidation to Propylene Oxide, Science, 292, pp. 1139-1141 Neumann, R. 

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