Studies on the Interaction between Long Chain Alcohols and Alkyl Sulfates. I. Molecular Association between Long Chain Alcohols and Corresponding Alkyl Sulfates

Abstract

Abstract Molecular interaction between long chain alcohols and corresponding alkyl sulfates, such as dodecyl alcohol-sodium dodecyl sulfate, tetradecyl alcohol-sodium tetradecyl sulfate and hexadecyl alcohol-sodium hexadecyl sulfate, was studied by measurement of heat of complex formation, differential thermal analysis and infrared spectroscopy. It was found that there were two kinds of complexes, I and II, differing in the composition of alcohols and corresponding sulfates. The former is stable at temperatures below the melting point of alcohol, the molar ratio of alcohol to sulfate being 0.53–0.63. The latter is stable at temperatures above the melting point of alcohol, its molar ratio being 1.0. The heat of formation of II is 7–8 kcal/mol, which suggests that the complex is formed by a force similar to hydrogen bonding between alcohols and sulfates. The peak temperature in the DTA curve due to decomposition of the complex is about 10°C lower in I than in II and the characteristic absorption bands in IR spectrum are 3480 cm−1 and 3520 cm−1 in I and II, respectively, which correspond to hydrogen bond between two components.