question_answer

At room temperature tertiary alcohols form white turbidity very fast with Lucas reagent while primary alcohols do not. Give reason.

Answer:

                 A carbocation intermediate is formed when \[HCl(g)\] reacts with an alcohol in the presence of anhydrous \[ZnC{{l}_{2}}\](dehydrating agent). Since tertiary carbocation is very stable while primary carbocation is rather unstable therefore, tertiary alcohols react very fast with Lucas reagent to form white turbidity immediately while the primary alcohols do not react at room temperature. \[\underset{\begin{smallmatrix}   \\    \\  \text{Alcohol} \end{smallmatrix}}{\mathop{R-\underset{\centerdot \,\,\centerdot }{\overset{\centerdot \,\,\centerdot }{\mathop{O}}}\,-H}}\,+H-Cl\xrightarrow{\,}\underset{\begin{smallmatrix}  \text{Protonated} \\  \,\,\,\,\text{alcohol} \end{smallmatrix}}{\mathop{R-\overset{\oplus }{\mathop{\underset{\begin{smallmatrix}  | \\  H \end{smallmatrix}}{\mathop{O}}\,}}\,-H}}\,\]     \[\xrightarrow{\text{Slow}}\,\underset{\begin{align}   &  \\  &  \\  &  \\  & \text{Carbocation} \\ \end{align}}{\mathop{{{R}^{+}}}}\,\,\xrightarrow[Fast]{C{{l}^{-}}}\,\underset{\begin{align}   &  \\  &  \\  &  \\  & \text{Alkyl}\,\,\text{chloride} \\ \end{align}}{\mathop{R-Cl}}\,\]