--- title: "Monsanto acetic acid process Template | MolDraw" url: https://www.moldraw.com/templates/cycle-monsanto-acetic-acid/ description: "Monsanto acetic acid process template: Rhodium cycle of the Monsanto process: SN2 oxidative addition of methyl iodide to cis-[Rh(CO)₂I₂]⁻ (rate-determining)…" lang: en publisher: Scidart Academy generated: 2026-11-13 --- [MolDraw](https://www.moldraw.com/) › [Templates](https://www.moldraw.com/templates/) › [Catalytic cycles](https://www.moldraw.com/templates/catalytic-cycles/) › Monsanto acetic acid process [Catalytic cycles](https://www.moldraw.com/templates/catalytic-cycles/)Premium # Monsanto acetic acid process template ![Monsanto acetic acid process template: Rhodium cycle of the Monsanto process: SN2 oxidative addition of methyl iodide to cis-[Rh(CO)₂I₂]⁻ (rate-determining), methyl migration to CO with uptake of CO, and reductive elimination of acetyl iodide, which water hydrolyses to acetic acid and HI; HI turns methanol back into CH₃I; key step: SN2 attack of Rh(I) on CH₃I.](https://www.moldraw.com/templates/cycle-monsanto-acetic-acid.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). Rhodium cycle of the Monsanto process: SN2 oxidative addition of methyl iodide to cis-[Rh(CO)₂I₂]⁻ (rate-determining), methyl migration to CO with uptake of CO, and reductive elimination of acetyl iodide, which water hydrolyses to acetic acid and HI; HI turns methanol back into CH₃I; key step: SN2 attack of Rh(I) on CH₃I. ## What the template shows - Rh/I⁻ catalysed carbonylation of methanol: oxidative addition of CH₃I is rate-determining - Overall: CH₃OH + CO → CH₃CO₂H (cat. [Rh(CO)₂I₂]⁻, HI/CH₃I, H₂O, 150–200 °C, 30–60 bar) - Rh(I), 16 e⁻, square planar - Rate = k[Rh][CH₃I]: zero order in CO and methanol, so oxidative addition of CH₃I is the slow step. - Migratory insertion first gives the 16 e⁻ five-coordinate acyl [CH₃CORh(CO)I₃]⁻, which takes up CO to the 18 e⁻ complex drawn. - Iodide is a co-catalyst: an organic cycle (CH₃OH → CH₃I, CH₃COI → CH₃CO₂H) feeds the metal cycle; selectivity is over 99% based on methanol. - The BP Cativa process uses [Ir(CO)₂I₂]⁻ with a Ru promoter: oxidative addition of CH₃I is much faster at Ir, and migratory insertion becomes rate-determining. - Key step: SN2 oxidative addition of CH₃I - The electron-rich Rh(I) anion uses a filled d orbital (drawn as a lone pair) to attack the methyl carbon from the back; iodide leaves and then binds Rh, giving the six-coordinate Rh(III) methyl. This step is rate-determining: rate = k[Rh][CH₃I]. - methyl iodide - CO ligands are named in the captions, not drawn · electron counts by the ionic method (I⁻ and CH₃⁻ as 2 e⁻ donors) · every part of this figure is editable Drawn with 25 atoms, 6 arrows, 51 shapes – every one editable in MolDraw. ## Sources - [Housecroft & Sharpe, Inorganic Chemistry, 5th ed., Pearson 2018, ch. 25](https://openlibrary.org/isbn/9781292134147) Textbook - [Crabtree, The Organometallic Chemistry of the Transition Metals, 6th ed., Wiley 2014, ch. 9](https://openlibrary.org/isbn/9781118138076) 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 Monsanto acetic acid process template free? You can preview the Monsanto acetic acid process 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 Monsanto acetic acid process 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 does a catalytic cycle template show? The active catalyst, each intermediate around the cycle, the substrates that enter and the products that leave, with each elementary step named on its arrow. ## More catalytic cycles templates [**Suzuki–Miyaura coupling**Free · Catalytic cycles](https://www.moldraw.com/templates/cycle-suzuki-miyaura/)[**Mizoroki–Heck reaction**Free · Catalytic cycles](https://www.moldraw.com/templates/cycle-mizoroki-heck/)[**Olefin metathesis (Chauvin mechanism)**Free · Catalytic cycles](https://www.moldraw.com/templates/cycle-olefin-metathesis/)[**Buchwald–Hartwig amination**Premium · Catalytic cycles](https://www.moldraw.com/templates/cycle-buchwald-hartwig/)[**Sonogashira coupling**Premium · Catalytic cycles](https://www.moldraw.com/templates/cycle-sonogashira/)[**Negishi coupling**Premium · Catalytic cycles](https://www.moldraw.com/templates/cycle-negishi/)[**Stille coupling**Premium · Catalytic cycles](https://www.moldraw.com/templates/cycle-stille/)[**Wilkinson's catalyst: alkene hydrogenation**Premium · Catalytic cycles](https://www.moldraw.com/templates/cycle-wilkinson-hydrogenation/) ## Related pages [**All Catalytic cycles templates**16 templates](https://www.moldraw.com/templates/catalytic-cycles/)[**All chemistry templates**525 templates in 31 categories](https://www.moldraw.com/templates/) MolDraw Pro Download all 525 templates - Export the 437 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.