COMEDK2024Morning ShiftChemistryHydrocarbonsActual
An unsaturated hydrocarbon [ A ] reacts with HBr in presence of Benzoyl peroxide to yield [B] Compound [A] when reacted with cold, dilute alkaline KMnO ₄ gave compound [C], 2-Methylbutane-2, 3-diol But when [A] is reacted with hot KMnO ₄ , it yielded CH ₃ COOH and a compound [D] Identify compounds [A], [B] and [D]
Options
- A[A] 2-Methylbut-2-ene [B] 2-Bromo-3-methylbutane [D] Propanone
- B[A] Pent-2-ene [B] 2-Bromopentane [D] Propanal
- C[A] Pent-1-ene [B] 1-Bromopentane [D] Propanoic acid
- D[A] 3-Methylbut-1-ene [B] 1-Bromo-3-methylbutane [D] Propanoic acid.
Correct answer
A. [A] 2-Methylbut-2-ene [B] 2-Bromo-3-methylbutane [D] Propanone
Step-by-step solution
Compound [A] reacts with cold, dilute alkaline KMnO ₄ to form 2-methylbutane-2,3-diol. This reaction is a syn-hydroxylation of an alkene. The structure of 2-methylbutane-2,3-diol is CH ₃- C(OH)(CH ₃)- CH(OH) - CH ₃ . The corresponding alkene [A] is 2-methylbut-2-ene, which has the structure CH ₃- C(CH ₃)= CH - CH ₃ . Reaction of 2-methylbut-2-ene with hot KMnO ₄ (oxidative cleavage) breaks the double bond: CH ₃- C(CH ₃)= CH - CH ₃ hot KMnO ₄ CH ₃- C(=O) - CH ₃ + CH ₃- COOH . Here, CH ₃- COOH is acetic acid and [D]