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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3o3148

Select the correct statement(s) about the conversion of alcohols into alkyl halides.

  1. A converts a primary alcohol into the bromide without carbocation rearrangement because the displacement of the group is an SN2 reaction.
  2. BWith a chiral secondary alcohol, in pyridine gives the chloride with inversion because free chloride attacks the alkyl chlorosulfite from the back.
  3. CTreating a chiral secondary alcohol with TsCl in pyridine gives the tosylate with inversion at the carbinol carbon.
  4. DConcentrated HCl converts neopentyl alcohol into neopentyl chloride cleanly, without rearrangement.

Answer: A, B

Pyridine supplies free chloride for the backside displacement, giving inversion, and the SN2 displacement of avoids carbocations. Neopentyl alcohol in concentrated acid either reacts extremely slowly or rearranges through a cation and does not give neopentyl chloride cleanly. Tosylation only breaks the O-H bond; the C-O bond is untouched, so the configuration is retained, not inverted.
Practice Organic Reaction Mechanisms III: Nucleophilic Substitution More on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

More questions on SN1 vs SN2: substrate, nucleophile, solvent, leaving group