Alkenes combine with carbon monoxide and hydrogen in presence of octacarbonyldicobalt as catalyst un — Hydrogen Chemistry Question

💡 Solution & Explanation

# Hydroformylation Reaction **Reaction Overview:** Alkenes react with CO and $H_2$ in presence of $Co_2(CO)_8$ catalyst under high temperature and pressure. **Step-by-step mechanism:** 1. **Catalyst activation:** $Co_2(CO)_8$ dissociates to form active cobalt hydride species ($HCo(CO)_n$) 2. **Alkene coordination:** The alkene inserts into the $Co-H$ bond: $$R-CH=CH_2 + HCo(CO)_n \rightarrow R-CH_2-CH_2-Co(CO)_n$$ 3. **CO insertion:** Carbon monoxide inserts into the alkyl-cobalt bond: $$R-CH_2-CH_2-Co(CO)_n + CO \rightarrow R-CH_2-CH_2-CO-Co(CO)_n$$ 4. **Hydrogenolysis:** $H_2$ cleaves the $Co-C$ bond, releasing the product: $$R-CH_2-CH_2-CO-Co(CO)_n + H_2 \rightarrow R-CH_2-CH_2-CHO + HCo(CO)_n$$ **Product:** **Aldehydes** (specifically, primary aldehydes when terminal alkenes are used) This is the **hydroformylation** (or oxo process), producing aldehydes with one additional carbon atom containing the aldehyde group.