See image — Amines Chemistry Question

💡 Solution & Explanation

Concept: Reduction of nitriles with LiAlH4. Step 1: Identify the starting material. The starting material is butanenitrile (CH3CH2CH2-CN), a nitrile with a three-carbon chain attached to the CN group, making it a four-carbon nitrile overall. Step 2: Recall the reaction of nitriles with LiAlH4. LiAlH4 (excess) reduces a nitrile (R-CN) to a primary amine (R-CH2-NH2). The CN group is reduced by adding two hydrogen atoms across the triple bond to give an imine intermediate, which is further reduced to give a primary amine. The net result is: R-CN + LiAlH4 (excess), then H3O+ --> R-CH2-NH2. Step 3: Apply to this substrate. CH3CH2CH2-CN is reduced to CH3CH2CH2-CH2-NH2, which is butan-1-amine (1-aminobutane). This is a primary amine where the CN carbon becomes a CH2 bearing the NH2 group. Step 4: Match to the answer choices. - Option (a): A plain alkane (no nitrogen, no oxygen) - cannot result from nitrile reduction. Incorrect. - Option (b): Shows a propyl chain with a -CH2NH2 group, giving CH3CH2CH2CH2NH2 (butan-1-amine / 1-aminobutane). This matches R-CH2-NH2 where R = propyl. Correct. - Option (c): An alcohol (OH group). LiAlH4 on a nitrile does not give an alcohol. Incorrect. - Option (d): A gem-diamine (two NH2 on the same carbon). This is not the product of nitrile reduction; nitriles give only one NH2. Incorrect. Therefore, the correct answer is B.