tags
alcoholbisulfitesodium bisulfidebisulphideDCMmagnesium sulfatemanganese sulfate monohydratebenzylbenzalmanganesesodium carbonatepermanganatepotassium permanganatemanganese dioxidebenzaldehydesodium bisulfitemanganese sulfatedioxidedichloromethane
video tutorial Manganese dioxide and preparation of benzaldehyde from benzyl alcohol
- Prepared active manganese dioxide (MnO2) by dissolving potassium permanganate in warm water, then adding manganese sulfate monohydrate, filtering the brown mud, drying to a fine brown powder, yielding about 65 g MnO2 for use in oxidation.
- Oxidized benzyl alcohol to benzaldehyde using the prepared MnO2 in dichloromethane (DCM) with reflux; MnO2 was added gradually over about an hour; after cooling, the mixture was filtered and washed with DCM to recover product; the brown/black solid contained manganese oxides to be recycled.
- Purified the crude benzaldehyde by forming a sodium bisulfite adduct, washing the adduct with DCM, then treating with saturated sodium carbonate to release benzaldehyde; the organic layer was dried (MgSO4) and filtered to yield 12.6 g benzaldehyde (43% of starting benzyl alcohol).
- Notes: MnO2 can contaminate glassware and is reusable; solvent recovery and purification steps (bisulfite purification) were used to remove benzyl alcohol and other organics; the process aims for a practical yield without overoxidation.
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