Chemoselective transfer hydrogenation reactions over calcined-layered double hydroxides

Article abstract of DOI:10.1246/bcsj.73.1425

Layered double hydroxides (LDH) of the hydrotalcite type (also known as anionic clays) could be utilized as precursors of mixed metal oxides with pronounced basic properties. Upon calcination in air at ~ 723 K, these materials give rise to solid solutions between M²⁺ and M³⁺ ions (Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Al³⁺, Fe³⁺, Cr³⁺, respectively). The function of such materials was studied in the reduction of nitrobenzene to aniline using isopropanol as a hydrogen donor, and in the hydrogen-transfer reduction of p-chloronitrobenzene, p-nitroanisole, o-nitrotoluene, m-dinitrobenzene, acetophenone, benzophenone, p-nitroacetophenone, p-nitrobenzophenone, and cinnamaldehyde. The Ni^II-Al^III (mole ratio = 3:1) catalyst was very active in bringing about chemoselective reduction compared to other calcined LDH.