Solid state phase behaviors of dodecyldimethylamine oxide: protonation andcounterion effects

Solid phase behaviors of dodecyldimethylamine oxide (C12DAO) studied by dif ferential scanning calorimetry and X-ray scattering have shown clearly the effects of protonation. Besides the protonated (cationic) (C12DAO HCl) and the nonionic (C12DAO) species, 1:1 composition or hemihydrochloride (C12DAO 1/2 HCl) was shown to be a stable complex. The phase behavior of C12DAOHCl was similar to that of dodecylammonium chloride rather than dodecyltrimeth ylammonium chloride (C12TACl), although similar crystal structure was sugge sted for C12DAOCl and C12TABr. Solid phase behaviors changed dramatically b y changing the counterion from Cl- to NO3- or SO42- for both the cationic a nd 1:1 species. (C) 2000 Elsevier Science B.V. All rights reserved.