Synthesis, Surface Properties, and Hydrolysis of Chemodegradable Anionic Surfactants: Diastereomeric Sodium Carboxylates Derived from 1,3-Dioxane

✍ Scribed by Andrzej Piasecki; Piotr Ruchała

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 131 KB
• Volume: 226
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2000.6820

✦ Synopsis

Mixtures of cis-and trans-2-n-alkyl-5-carboxy-5-methyl

-1,3dioxanes, 3a-3e, were obtained in the reaction of aliphatic aldehydes 1a-1e (from n-octanal to n-dodecanal) with 2,2-bis(hydroxymethyl)propionic acid (DMPA), 2, carried out in boiling n-hexane or in the isomerization reaction of an appropriate cis-3a-3e. Pure trans-3a-3e were isolated from the above mixtures by selective crystallization and then converted into surface-active sodium salts, trans-4a-4e, by neutralization with sodium hydroxide or sodium methoxide. Surface properties of these surfactants, i.e., critical micelle concentration (CMC), surface excess concentration ( CMC ), surface area demand per molecule (A CMC ), effectiveness of surface tension reduction (γ CMC ), and standard free energy of micellization ( G • mic ) were determined and compared with the appropriate surface properties of isomeric cis-4a-4e. It was shown that the properties of surfactants under study are dependent both on the length of a hydrophobic n-alkyl substituent at the C2 carbon atom of the 1,3-dioxane ring and on the configuration of a polar sodium carboxylate group at C5. The acids 3 undergo hydrolysis/ isomerization reactions in acidic D 2 O/d 6 -DMSO media. The cis isomers are hydrolyzed faster than trans isomers probably due to the steric hindrance of the axial methyl group at C5 of the latter ones.