Give structures of the products you would expect when each of the following alcohol reacts with (a) HCl–ZnCl₂ (b) HBr and (c) SOCl₂. (i) Butan-1-ol (ii) 2-Methylbutan-2-ol
(a) CH₃CH₂CH₂CH₂Cl (1-Chlorobutane) (b) CH₃CH₂CH₂CH₂Br (1-Bromobutane) (c) CH₃CH₂CH₂CH₂Cl (1-Chlorobutane)
(a) CH₃CH₂C(Cl)(CH₃)CH₃ (2-Chloro-2-methylbutane) (b) CH₃CH₂C(Br)(CH₃)CH₃ (2-Bromo-2-methylbutane) (c) CH₃CH₂C(Cl)(CH₃)CH₃ (2-Chloro-2-methylbutane)
Explanation
The question tests the conversion of alcohols to alkyl halides using different reagents. Butan-1-ol is a primary alcohol, while 2-Methylbutan-2-ol is a tertiary alcohol. With HCl-ZnCl₂ (Lucas reagent), tertiary alcohols react immediately while primary alcohols require heating. With HBr, both alcohols undergo nucleophilic substitution to form alkyl bromides. With SOCl₂ (thionyl chloride), alcohols are converted to alkyl chlorides with evolution of SO₂ and HCl gas. The -OH group is replaced by the respective halide ion in all cases.