Question

Show how you will synthesise:
(i) 1-Phenylethanol from a suitable alkene.
(ii) Cyclohexylmethanol using an alkyl halide by a \[S{N^2}\]reaction.
(iii) Pentan-1-ol using a suitable alkyl halide.

Answer 1

Hint: These reactions are either electrophilic addition or nucleophilic substitution reaction. In an electrophilic addition reaction, a $\pi $ bond is broken and two new $\sigma $ bonds are formed. In nucleophilic substitution reaction, a leaving group is replaced by an electron rich compound.

Complete step by step solution:
Synthesis of the following reaction:
(i) 1-phenylethanol from suitable alkene.
Alkene is treated with \[{H_2}O\]in the presence of acid (acid catalyzed hydrolysis) to give 1-phenylmethanol


(ii) Cyclohexylmethanol using an alkyl halide by a \[S{N^2}\] reaction.
When chloromethylcyclohexane is treated with sodium hydroxide, then it will give cyclohexylmethanol by \[S{N^2}\]mechanism.


(iii) Pentan-1-ol using a suitable alkyl halide.
When chloropentane is treated with aq.$NaOH$, then it will give pentan-1-ol.
\[\mathop {C{H_3}C{H_2}C{H_2}C{H_2}C{H_2}}\limits_{\left( {1 - Chloropen\tan e} \right)} - Cl + \mathop {aq.NaOH}\limits_{\left( \begin{subarray}{l}
  Sodium \\
  Hydroxide
\end{subarray} \right)} \xrightarrow{{}}\mathop {C{H_3}C{H_2}C{H_2}C{H_2}C{H_2} - OH + NaCl}\limits_{\left( {Pen\tan - 1 - ol} \right)} \]

Note: Alpha methylbenzyl alcohol appears as a colourless liquid which is insoluble in water and less dense than water. Cyclohexylmethanol is an organic compound and these reactions are bimolecular nucleophilic substitution reactions. 1 - Pentanol is a colourless liquid with a distinctive aroma. It is the straight- chain form of amyl alcohol and the hydroxyl group is the active site of many reactions. Electrophilic addition reactions are an important class of reaction that allow the inter conversion of $C = C$and $C \equiv C$ into a range of important functional groups including alkyl halides and alcohols. Addition reaction is the reverse of elimination reactions and in nucleophilic substitution reactions, the stronger nucleophile replaces a weaker nucleophile.