Control of calcium accessibility over hydroxyapatite by post-precipitation steps: influence on the catalytic reactivity toward alcohols.

Hydroxyapatites are increasingly used as heterogeneous catalysts since they present atypical behaviours for many acid base reactions. The aim of this study was to discuss the possible involvement of Ca Lewis and/or PO-H Brønsted acid sites belonging to the hydroxyapatite system in the conversion of 2-methylbut-3-yn-1-ol, a model molecule that is known to account for the acid base properties, and of ethanol into n-butanol. A series of hydroxyapatite samples with similar bulk properties was prepared from a lone precipitation batch, but by varying the conditions of the washing and drying steps.

Ruthenium-catalyzed dehydrogenation of ammonia boranes.

The dehydrogenation of ammonia borane (AB) and methylammonia borane (MeAB) is shown to be catalyzed by several Ru-amido complexes. Up to 1 equiv of H2 (1.0 system wt %) is released from AB by as little as 0.