--- title: "α-Halogenation of a ketone (acid) Template | MolDraw" url: https://www.moldraw.com/templates/ketone-alpha-halogenation/ description: "α-Halogenation of a ketone (acid) template: Propanone with Br₂ in ethanoic acid: O-protonation, slow loss of an α-H to the enol, attack of the enol on Br₂…" 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/) › α-Halogenation of a ketone (acid) [Mechanisms](https://www.moldraw.com/templates/mechanisms/)Premium # α-Halogenation of a ketone (acid) template ![α-Halogenation of a ketone (acid) template: Propanone with Br₂ in ethanoic acid: O-protonation, slow loss of an α-H to the enol, attack of the enol on Br₂ and loss of H⁺ give bromopropanone.](https://www.moldraw.com/templates/ketone-alpha-halogenation.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). Propanone with Br₂ in ethanoic acid: O-protonation, slow loss of an α-H to the enol, attack of the enol on Br₂ and loss of H⁺ give bromopropanone. ## Mechanism step by step The slow step is enol formation; the enol then attacks the halogen 1. **Protonation** – Acid activates the carbonyl 2. **Enol (slow)** – Water removes an α-H 3. **Enol attacks Br₂** – The C=C is the nucleophile 4. **Deprotonation** – Bromopropanone and HBr ## Key points - Rate = k[ketone][H⁺], independent of [Br₂]: Cl₂, Br₂ and I₂ react at the same rate (the iodination of propanone experiment). - In acid it stops after one halogen: the C–Br makes the next enol slower to form. - In base every α-H is replaced; methyl ketones go on to the haloform reaction. - HBr is a product, so the reaction speeds up as it goes (autocatalysis). Drawn with 59 atoms, 15 arrows, 8 shapes – every one editable in MolDraw. ## Sources - [Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012, ch. 20](https://openlibrary.org/isbn/9780199270293) Textbook - [Smith, March's Advanced Organic Chemistry, 8th ed., Wiley 2020, ch. 12](https://openlibrary.org/isbn/9781119371809) Textbook - [Lapworth, J. Chem. Soc., Trans. 1904, 85, 30](https://doi.org/10.1039/CT9048500030) Original paper ## 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 α-Halogenation of a ketone (acid) template free? You can preview the α-Halogenation of a ketone (acid) 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 α-Halogenation of a ketone (acid) 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. You can open it in MolDraw, change the substrate and reuse it. ## More mechanisms templates [**Aldol addition**Free · Mechanisms](https://www.moldraw.com/templates/aldol-addition/)[**SN2 substitution**Free · Mechanisms](https://www.moldraw.com/templates/sn2-substitution/)[**SN1 substitution**Free · Mechanisms](https://www.moldraw.com/templates/sn1-substitution/)[**E2 elimination**Premium · Mechanisms](https://www.moldraw.com/templates/e2-elimination/)[**E1 elimination**Premium · Mechanisms](https://www.moldraw.com/templates/e1-elimination/)[**Acid-catalysed hemiacetal formation**Premium · Mechanisms](https://www.moldraw.com/templates/hemiacetal-formation/)[**Imine formation**Premium · Mechanisms](https://www.moldraw.com/templates/imine-formation/)[**Ester hydrolysis (saponification)**Premium · Mechanisms](https://www.moldraw.com/templates/ester-saponification/) ## Related pages [**Curved Arrow Mechanism Worksheet**Free printable worksheet](https://www.moldraw.com/educational-materials/curved-arrow-mechanism-worksheet/)[**Predict the Product Worksheet: Organic Reactions**Free printable worksheet](https://www.moldraw.com/educational-materials/predict-the-product-worksheet/)[**All Mechanisms templates**42 templates](https://www.moldraw.com/templates/mechanisms/)[**All chemistry templates**421 templates in 31 categories](https://www.moldraw.com/templates/) MolDraw Pro Download all 421 templates - Export the 335 premium templates as PNG, SVG or PDF - AI chemistry assistant - Structure scanning from images - Cloud save and teaching slides [See Pro plans](https://www.moldraw.com/pricing) Free templates stay free. Every template can be opened and edited in MolDraw.