Dimethyldodecylamine oxide, preparation

To provide a specific example, Imae and Ikeda (ref. 479) state that amine oxide is very hydrophilic and can constitute a good polar head group for nonionic surfactants at neutral pH. Dimethyl-dodecylamine oxide was first prepared by Hoh et al. (ref. 494), and its surface-active properties in aqueous solutions were investigated by measurements of surface tension (ref. 495), light scattering (ref. 496-498), and hydrodynamic properties (ref. 499). It was found that dimethyldodecylamine oxide can form only spherical micelles in water and aqueous NaCl solutions, when the micelle concentration is dilute (ref. 496,498). Similarly, the homolog dimethyltetradecylamine oxide forms only spherical micelles in water (ref. 496). 

Materials. Trimethylamine N-oxide dihydrate (98%) from Aldrich and N-dimethyldodecylamine N-oxide (97%) from Fluka Chemie were used as received. N-dimethylhexylamine N-oxide and N-dimethyloctylamine N-oxide were prepared by reaction of the corresponding tertiary amine with hydrogen peroxide (12). Both samples were isolated as crystalline solids and were >99% pure, based on acid/base titrations and spectrometric methods. Both samples were very hygroscopic. Reagent grade NaBr, 0.1 N and 2.0 N HC1 were from J.T. Baker Chemical Co. and the all solutions were prepared using distilled and deionized water. The pH was monitored using an Orion Ross combination pH electrode and an Orion EA 940 meter. 

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