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Gattermann–Koch reaction template
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CO takes H⁺ from HCl with AlCl₃ to form the formyl cation HC≡O⁺; benzene attacks it and loses H⁺ to give benzaldehyde.
Mechanism step by step
CO and HCl with AlCl₃/CuCl formylate benzene to benzaldehyde
- Formyl cation – The carbon lone pair of CO takes H⁺ from HCl; AlCl₃ takes Cl⁻
- Electrophilic attack – The ring attacks the formyl carbon: an arenium ion
- Deprotonation – Cl⁻ (from AlCl₄⁻) takes H⁺; AlCl₃ is regenerated
Key points
- Formyl chloride (HCOCl) is unstable, so a Friedel–Crafts formylation is done with CO + HCl instead.
- CuCl helps by binding CO; at high pressure it is not needed.
- Toluene gives mainly 4-methylbenzaldehyde. Phenols and phenol ethers do not work well; use the Gattermann (HCN) or Reimer–Tiemann reaction.
- Like Friedel–Crafts acylation, deactivated rings (nitrobenzene) do not react.
Drawn with 68 atoms, 10 arrows, 6 shapes – every one editable in MolDraw.
Sources
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Frequently asked questions
Is the Gattermann–Koch reaction template free?
You can preview the Gattermann–Koch reaction 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 Gattermann–Koch reaction 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.
Which name reactions are included?
Over seventy, covering the reactions most often asked in school-leaving exams (A-level, IB, CBSE, JEE and NEET) and first-year university courses, including condensations, rearrangements, oxidations, reductions and aromatic substitutions.