In the novel solid phase system consisting of cetylpyridinium dodecatungstate (CetylPy(10)[H2W12O42]) catalyst/ solid oxidant (urea-H2O2)/ apatite disperse phase, the 0-insertion reaction (epoxidation) of C=C double bond of cyclooctene proceeds at powdery solid state in the absence of organic solvents without stirring at room temperature. In the system, the formation of the epoxide was affected by various forms of hydroxyapatite powders (HAps) used as a solid disperse phase. The high crystallinity and low surface area of HAp and the uniform size of spherical particles of RAp were found to be important factors as an effective solid disperse phase for assisting the epoxidation. The factors were quite different from those of common solid supports used for fixing the catalyst in liquid-solid heterogeneous reactions. Taking account of the kinetic behavior in the solid-phase-epoxidation system, key points for promoting the reaction are considered to be the diffusion of liquid reactant and its proximity to the active catalyst. The effective forms of apatites might have advantages in these points.

Keywords: apatite; solid disperse phase; epoxidation; polyoxometalate; hydrogen peroxide; green chemistry