video tutorial Chromium trioxide and pyridinium chlorochromate

Pyridinium chlorochromate (PCC) synthesis summary

• Convert potassium dichromate to chromic acid by dissolving in warm water and adding concentrated sulfuric acid, forming chromic acid in solution.
• Cool and crystallize hydrated chromium trioxide by further sulfuric acid addition and cooling; obtain damp crystals (~65 g) contaminated with acid/sulfate salts.
• Dissolve crude CrO3 in hydrochloric acid and water to form an orange chlorochromic acid solution.
• React with pyridine to yield pyridinium chlorochromate; crystals form upon cooling to ~20°C.
• Filter under vacuum and dry to obtain PCC crystals; typical yield ~35 g per batch (~70% of starting dichromate).
• Dispose of chromium(VI) waste by diluting and reducing with isopropanol before disposal; monitor exotherm and color changes.
• Pyridinium chlorochromate is a reagent for selectively oxidizing primary alcohols to aldehydes, without overoxidation to carboxylic acids, under appropriate conditions and with water exclusion.