Synthesis and reactions of N-methylbenzylammonium fluorochromate(VI) on silica gel, a selective and efficient heterogeneous oxidant.
N-Methylbenzylammonium fluorochromate(VI) (MBAFC) is easily synthesized by addition of N-methylbenzylamine to an aqueous solution of CrO3 and HF. MBAFC shows selectivity in the oxidation of aryl alcohols to their corresponding aldehydes and ketones under mild conditions. The durability, ease of work up and efficiency of MBAFC are considerably increased upon its absorption on silica gel.
Green bromine: in situ generated catalyst for the selective oxidation of alcohols using H2O2 as a benign oxidant
The selective oxidation of benzylic/secondary alcohols to the corresponding aldehydes/ketones with a catalytic amount of bromide–bromate (10 mol%) couple and H2O2 as a benign oxidant has been developed. The oxidation reactions were achieved through acid (15 mol%) activation of 5 : 1 mole ratios of a bromide–bromate couple for the in situ generation of the Br2/BrOH species. The In situ generation of the Br2/BrOH species is also supported by UV-Visible spectrophotometric studies. High selectivity and yields of aldehydes/ketones were obtained without the use of any transition metal catalyst under aqueous conditions.
Sur une serie d'oxyfluores du chrome VI de formule MCrO3F où M = K, Rb, Cs et NH4
Abstract The compounds MCrO 3 F, (M = K, Rb, Cs and NH 4 ) have been prepared, then studied by X-Ray. diffraction — From these results it appears a different occupation of the same crystallographic position by O and F at the top of the tetrahedron CrO 3 F − against M. That means a different reactivity of these compounds and shows the importance of the F atom. The distances CrO(1,60A) and CrF (near of 1,74 A) are discussed. The CrO 3 F − compounds are compared with SO 3 F − , ClO 4 − , CrO 3 Cl − and PO 2 F 2 − compounds.