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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3nc248

The dibromide shown is heated with an excess of potassium phthalimide, and the product is then treated with hydrazine. Select all the correct statements.

  1. AThe final product is a diamine with four carbons
  2. BThe same diamine can be obtained from hexanediamide by the Hofmann bromamide reaction
  3. CUsing only aqueous ammonia instead gives a clean sample of the diamine without by-products
  4. DEach nitrogen of the product is primary

Answer: A, B, D

The compound shown is 1,4-dibromobutane. Double Gabriel substitution followed by hydrazinolysis gives butane-1,4-diamine, in which both nitrogens are primary. Hofmann degradation of hexanediamide (adipamide) removes one carbon from each end and gives the same diamine. Ammonia alone gives mixtures of primary, secondary and tertiary products (and cyclised pyrrolidine), so statement three is false.
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