--- title: "Acetal formation Template – Chemistry Diagram | MolDraw" url: https://www.moldraw.com/templates/acetal-formation/ description: "Acetal formation template: From the hemiacetal of ethanal and methanol: protonation of OH, loss of water, attack by methanol and loss of H⁺ give…" 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/) › Acetal formation [Mechanisms](https://www.moldraw.com/templates/mechanisms/)Premium # Acetal formation template ![Acetal formation template: From the hemiacetal of ethanal and methanol: protonation of OH, loss of water, attack by methanol and loss of H⁺ give 1,1-dimethoxyethane. Acetals protect aldehydes and ketones.](https://www.moldraw.com/templates/acetal-formation.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). From the hemiacetal of ethanal and methanol: protonation of OH, loss of water, attack by methanol and loss of H⁺ give 1,1-dimethoxyethane. Acetals protect aldehydes and ketones. ## Mechanism step by step The hemiacetal loses water to an oxocarbenium ion, which a second alcohol traps 1. **Protonation** – The hemiacetal OH takes H⁺ (hemiacetal from the first MeOH) 2. **Loss of water** – The OMe lone pair pushes water out: oxocarbenium ion 3. **Methanol adds** – The second alcohol attacks the cation 4. **Deprotonation** – The acetal; H₃O⁺ is regenerated ## Key points - Every step is reversible: removing water (Dean–Stark, molecular sieves) drives acetal formation; aqueous acid reverses it. - Acetals survive bases, nucleophiles, Grignard reagents and LiAlH₄, so they protect C=O. - Ethane-1,2-diol gives a cyclic acetal (1,3-dioxolane), favoured by entropy. - Open-chain hemiacetals are unstable; cyclic ones (sugars) are stable. Drawn with 62 atoms, 13 arrows, 8 shapes – every one editable in MolDraw. ## Sources - [Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012, ch. 11](https://openlibrary.org/isbn/9780199270293) Textbook - [Smith, March's Advanced Organic Chemistry, 8th ed., Wiley 2020, ch. 16](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 Acetal formation template free? You can preview the Acetal formation 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 Acetal formation 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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