Synthesis and surface properties of chemodegradable anionic surfactants: Sodium salts of sulfated 2‐n‐alkyl‐5‐hydroxymethyl‐5‐methyl‐1,3‐dioxanes

In acid‐catalyzed reactions of long‐chain aliphatic aldehydes (Ia‐d) (a,R=n‐C5H11; b,R=n‐C7H15; c,R=n‐C9H19; d,R=n‐C11H23) with 1,1,1‐tris(hydroxymethyl)‐ethane (II), 2‐n‐alkyl‐5‐hydroxymethyl‐5‐methyl‐1,3‐dioxanes (IIIa‐d) were obtained. Then they were reacted with SO3·pyridine complex in dry carbon tetrachloride solution, to obtain trisubstituted derivatives of 1,3‐dioxane (IVa‐d). They constitute a new group of chemodegradable, acetal‐type anionic surfactants, which may readily hydrolyze and oxidize to nonsurfactant compounds. Physical data of the new compounds and some surface properties, such as Krafft point, critical micelle concentration (CMC), surface tension of aqueous solution near CMC (γCMC) and wetting and foaming properties, were determined. Sodium salts of sulfated 2‐n‐alkyl‐5‐hydroxymethyl‐5‐methyl‐1,3‐dioxanes (IVa‐d) exhibit aqueous solution properties similar to those of the well‐known sodium alkyloligooxyethylene sulfates. Presence of the 5‐methyl‐1,3‐dioxane moiety in molecules of compounds IVa‐d introduces hydrophobic character comparable to the effect of three oxyethylene groups (‐CH2CH2O‐) or of two methylene groups (‐CH2‐) of the alkyl chain in sodium alkyl ether sulfates [R(OCH2CH2)mOSO3Na] with equal R value.