See image — Amines Chemistry Question

💡 Solution & Explanation

Step 1: Identify the starting material. The starting material is 3,3-dimethyl-1-butanol: (CH3)3C-CH2CH2OH. Step 2: Oxidation with K2Cr2O7/H2SO4/H2O/heat. The primary alcohol -CH2CH2OH is oxidized to a carboxylic acid -CH2COOH (since K2Cr2O7 in acidic aqueous conditions with heat oxidizes primary alcohols all the way to carboxylic acids). So A = (CH3)3C-CH2COOH (3,3-dimethylbutanoic acid). Step 3: Reaction with SOCl2. SOCl2 converts the carboxylic acid to an acid chloride. So B = (CH3)3C-CH2COCl (3,3-dimethylbutanoyl chloride). Step 4: Reaction with (CH3)2NH (2 moles). Dimethylamine reacts with the acid chloride to form an amide, with the second mole of amine acting as a base to neutralize the HCl produced. So C = (CH3)3C-CH2-CO-N(CH3)2 (N,N-dimethyl-3,3-dimethylbutanamide). Step 5: Reduction with LiAlH4 in diethyl ether, then H2O workup. LiAlH4 reduces an amide to an amine. The C=O of the amide is reduced to CH2, giving: (CH3)3C-CH2-CH2-N(CH3)2. This is: CH3-C(CH3)(CH3)-CH2-CH2-N(CH3)2, which matches option (b): CH3CCH2CH2N(CH3)2 with CH3 groups above and below the quaternary carbon. Why other options fail: - Option (a) contains a nitrile group, which is not formed in this sequence. - Option (c) has N(CH3)2 on a secondary carbon adjacent to the quaternary carbon, which would require a different reaction pathway. - Option (d) has both N(CH3)2 and OH on the same carbon, which is not the product of amide reduction. Therefore, the correct answer is B.