Unique reaction of layered double hydroxides with 4-chlorobutyric acid: Fid-Bau Portal

Unique reaction of layered double hydroxides with 4-chlorobutyric acid

Hayashi, Aki / Nakayama, Hirokazu

Abstract Layered double hydroxides (LDH), namely, carbonate-type MgAl-layered double hydroxides (LDH2-CO3 and LDH3-CO3 with an Mg/Al ratios of 2 and 3, respectively), and nitrate-type MgAl layered double hydroxides (LDH2-NO3) with an Mg/Al ratio of 2, were reacted with 4-chlorobutyric acid. Typically, the reaction results in the exchange between anionic 4-chlorobutyric acid and the anions in the interlayer, which significantly increases the basal spacing of the LDH. However, the increase in the basal spacing in this study was only 0.01–0.02 nm, and the basal spacing of LDH2-CO3 and LDH3-CO3 after the reaction was equal to that of chloride-type LDH (LDH-Cl). Furthermore, the release of carbonate ions from the interlayer space was confirmed using IR spectroscopy, and the ¹³C NMR results of the solution after the reaction showed that γ-butyrolactone was formed. These results confirmed the elimination of Cl⁻ and occurrence of lactonization in the interlayer. Notably, the number of chloride ions in the interlayer space increased with increasing reaction temperature for the reaction with LDH2-CO3.

Highlights • Cl-type LDH was unexpectedly obtained by reacting 4-chlorobutyric acid with LDH-CO3 in methanol. • The elimination of Cl of 4-chlorobutyric acid occurred in the interlayer space of LDH. • The reaction with LDH3-CO3 proceeded more efficiently than with LDH2-CO3.