See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Most Acidic Hydrogen **Step 1: Identify the structure** The compound is butanal: $CH_3-CH_2-CH_2-C(=O)-H$ The hydrogen atoms are on carbons C₁, C₂, C₃, and C₄ (numbered from the carbonyl carbon). **Step 2: Apply acidity principle** Hydrogen acidity increases with proximity to electron-withdrawing groups. The carbonyl oxygen ($C=O$) is highly electronegative and withdraws electron density through the carbon chain. **Step 3: Analyze each position** - **C₁-H (aldehyde H)**: Directly attached to $C=O$ — most electron-deficient - **C₂-H**: One carbon away from $C=O$ — moderately affected - **C₃-H**: Two carbons away — weakly affected - **C₄-H**: Three carbons away — minimal effect **Step 4: Compare acidity order** $$C_1\text{-}H > C_2\text{-}H > C_3\text{-}H > C_4\text{-}H$$ The aldehyde hydrogen (C₁-H) is **most acidic** because it's directly bonded to the carbonyl carbon, which is strongly polarized by the oxygen atom. This makes the H-C bond highly polar and the hydrogen readily ionizable. **Answer: (1) C₁-H** ✓