퐶퐻3퐶퐻푂+ 퐿푖퐴푙퐻4 →퐶퐻3퐶퐻2푂퐻 Nucleophile added in this reaction is — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

# LiAlH₄ Reduction of Acetaldehyde **Identifying the Nucleophile:** The reaction is: $CH_3CHO + LiAlH_4 \rightarrow CH_3CH_2OH$ **Step 1: Understand LiAlH₄ structure** $LiAlH_4$ dissociates to give $Al^{3+}$ and $H^-$ (hydride ion). The hydride is the reactive species. **Step 2: Identify nucleophilicity** In this reduction, $H^-$ (hydride ion) acts as a **nucleophile** because: - It carries negative charge (electron-rich) - It attacks the electrophilic carbonyl carbon ($C=O$) - It donates electron density to form a new C-H bond **Step 3: Reaction mechanism** - $H^-$ attacks the partially positive carbonyl carbon - Forms $CH_3CH(O^-)H$ intermediate - Protonation yields $CH_3CH_2OH$ **Conclusion:** The nucleophile is **$H^-$ (hydride ion)** or **$AlH_4^-$ (tetrahydridoaluminate ion)**, depending on how the question specifies it. If option D states "hydride ion" or "$H^-$" or "tetrahydridoaluminate," that is the correct answer.