--- title: "Syn dihydroxylation: OsO₄ and cold KMnO₄ Template | MolDraw" url: https://www.moldraw.com/templates/syn-dihydroxylation-oso4-kmno4/ description: "Syn dihydroxylation: OsO₄ and cold KMnO₄ template: OsO₄ adds to cyclohexene in one concerted step to give a cyclic osmate ester, hydrolysis releases…" lang: en publisher: Scidart Academy generated: 2026-11-13 --- [MolDraw](https://www.moldraw.com/) › [Templates](https://www.moldraw.com/templates/) › [Mechanisms](https://www.moldraw.com/templates/mechanisms/) › Syn dihydroxylation: OsO₄ and cold KMnO₄ [Mechanisms](https://www.moldraw.com/templates/mechanisms/)Premium # Syn dihydroxylation: OsO₄ and cold KMnO₄ template ![Syn dihydroxylation: OsO₄ and cold KMnO₄ template: OsO₄ adds to cyclohexene in one concerted step to give a cyclic osmate ester, hydrolysis releases cis-cyclohexane-1,2-diol and NMO reoxidises Os(VI) to OsO₄ (Upjohn); cold, dilute, basic KMnO₄ works the same way through a cyclic manganate ester.](https://www.moldraw.com/templates/syn-dihydroxylation-oso4-kmno4.webp) [Edit in MolDraw](https://www.moldraw.com/)Download with Pro Premium template. Preview and edit it free in MolDraw; downloading and exporting it is part of [MolDraw Pro](https://www.moldraw.com/pricing). OsO₄ adds to cyclohexene in one concerted step to give a cyclic osmate ester, hydrolysis releases cis-cyclohexane-1,2-diol and NMO reoxidises Os(VI) to OsO₄ (Upjohn); cold, dilute, basic KMnO₄ works the same way through a cyclic manganate ester. ## Mechanism step by step Both oxygens add to the same face through a cyclic ester: cyclohexene gives cis-cyclohexane-1,2-diol 1. **Osmate ester** – A concerted [3+2] cycloaddition: both C–O bonds form on the same face; Os(VIII) → Os(VI) 2. **Hydrolysis** – Water cleaves the two Os–O bonds; the C–O bonds are untouched, so the diol stays cis 3. **Reoxidation (Upjohn)** – N-Methylmorpholine N-oxide turns Os(VI) back into OsO₄, so only a catalytic amount of OsO₄ is needed 4. **Cold dilute KMnO₄** – Permanganate (cold, dilute, basic) gives a cyclic manganate(V) ester the same way; hydrolysis gives the same cis-diol and MnO₂ ## Key points - Syn addition is stereospecific: cyclohexene gives only cis-cyclohexane-1,2-diol (meso); cis-but-2-ene gives meso-butane-2,3-diol, trans-but-2-ene the racemic (2R,3R)/(2S,3S) diol. - OsO₄ is toxic, volatile and expensive, so it is used in catalytic amounts with a co-oxidant: NMO (Upjohn) or K₃Fe(CN)₆ (Sharpless asymmetric dihydroxylation with chiral ligands). - KMnO₄ must be cold, dilute and basic (Baeyer test: purple → brown MnO₂); hot or acidic KMnO₄ cleaves the diol to carbonyl compounds and acids. - For the anti (trans) diol use an epoxide then aqueous acid: epoxidation is syn, but ring opening is backside attack. Drawn with 110 atoms, 11 arrows, 10 shapes – every one editable in MolDraw. ## Sources - [Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012, ch. 19](https://openlibrary.org/isbn/9780199270293) Textbook - [Wade, Organic Chemistry, 8th ed., Pearson 2013, ch. 8](https://openlibrary.org/isbn/9780321768414) Textbook - [Smith, March's Advanced Organic Chemistry, 8th ed., Wiley 2020, ch. 15](https://openlibrary.org/isbn/9781119371809) Textbook ## How to use this template 1. Press **Edit in MolDraw**. The template opens on the canvas of the free MolDraw editor. 2. Change anything: move structures, edit atoms and labels, recolour highlights or delete what you do not need. 3. Add your own structures, arrows and text next to it, or combine several templates on one page. 4. Export the drawing as PNG, SVG or PDF for slides, worksheets, theses and papers. ## Frequently asked questions ### Is the Syn dihydroxylation: OsO₄ and cold KMnO₄ template free? You can preview the Syn dihydroxylation: OsO₄ and cold KMnO₄ template here and open and edit it in MolDraw for free. Downloading or exporting it is part of MolDraw Pro, together with the other premium templates. ### Can I edit the Syn dihydroxylation: OsO₄ and cold KMnO₄ template? Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it. ### Is the chemistry checked? Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page. ### What is a curly-arrow mechanism template? A ready-made drawing of a reaction mechanism in which curved arrows show where electron pairs move in each step. 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