Oxidising agents guide template

Oxidising agents guide: PCC, Dess–Martin periodinane, Swern, Jones reagent, KMnO₄, OsO₄, mCPBA and ozone, each with its conditions, selectivity and a substrate → product example.

What the template shows

• Common oxidants, what each one does, and a worked example for each
• What it does
• pyridinium chlorochromate, CH₂Cl₂, rt
• 1° alcohol → aldehyde (anhydrous, so it stops there); 2° alcohol → ketone.
• Dess–Martin (DMP)
• Mild, neutral, chromium-free: 1° → aldehyde, 2° → ketone; tolerates most other groups.
• (COCl)₂, DMSO, −78 °C; then Et₃N
• 1° → aldehyde, 2° → ketone via an alkoxysulfonium ion; Me₂S is the (smelly) by-product.
• CrO₃, H₂SO₄, H₂O / acetone
• Aqueous Cr(VI): 1° alcohol → carboxylic acid (via the aldehyde hydrate); 2° → ketone.
• hot, aqueous; then H₃O⁺
• Strong: benzylic C–H → ArCO₂H (needs a benzylic H); cleaves alkenes; cold, dilute and basic gives syn diols.
• cat. OsO₄, NMO, acetone / H₂O
• Alkene → syn-1,2-diol via a cyclic osmate ester (both OH on the same face).
• m-chloroperbenzoic acid, CH₂Cl₂
• Alkene → epoxide (concerted, syn, stereospecific); also Baeyer–Villiger: ketone → ester.
• CH₂Cl₂, −78 °C; then Me₂S (or Zn, AcOH)
• Cleaves C=C into two C=O. Reductive work-up gives aldehydes/ketones; H₂O₂ work-up gives acids.
• Choose by how far you want to go: PCC, DMP and Swern stop a 1° alcohol at the aldehyde; Jones (aqueous) and KMnO₄ continue to the acid.
• DMP and Swern avoid chromium and work under mild, nearly neutral conditions, so acid-sensitive groups survive.
• OsO₄ is toxic and expensive: it is used in catalytic amounts with NMO as the stoichiometric re-oxidant (Upjohn conditions).
• mCPBA, OsO₄ and O₃ all react with the electron-rich C=C; the more substituted the alkene, the faster it reacts with mCPBA and O₃.
• KMnO₄ side-chain oxidation needs at least one benzylic H: tert-butylbenzene is not oxidised.
• Every part of this figure is editable · sources on the template card

Drawn with 116 atoms, 35 shapes – every one editable in MolDraw.

Sources

• Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012, ch. 23 Textbook
• Wade, Organic Chemistry, 8th ed., Pearson 2013 Textbook
• Smith, March's Advanced Organic Chemistry, 7th ed., Wiley 2013 Textbook