Q48E - Organic Chemistry (Mcmurry)

Question

How would you prepare the following compounds from 1-phenylethanol?

More than one step may be required.

(a) Acetophenone 

(b) Benzyl alcohol

(c) m-Bromobenzoic acid 

(d) 2-Phenyl-2-propanol

Step-by-Step Solution

Answer

(a) 

(b)

(c) 

(d) 

Step 1: Reactions of alcohols

Secondary alcohols can be converted to ketones in the presence of acidified ${\mathbf{CrO}}_{\mathbf{3}}$.The oxidation of a secondary aromatic alcohol in the presence of ${\mathbf{KMnO}}_{\mathbf{4}}$ gives carboxylic acid. This gets reduced with lithium aluminium hydride to produce a primary alcohol.

Step 2: Proposing structure of several compounds from the 1 H NMR spectrum

(a) The compound 1-phenylethanol reacts with  and  to form acetophenone. The reaction can be given as:

Reaction (a)

(b)The compound, 1-phenylethanol reacts with and to form benzoic acid. This further reacts with and to form benzyl alcohol. The reaction can be given as:

Reaction (b)

(c) The compound, 1-phenylethanol reacts with and to form benzoic acid. This further reacts with and to form m-bromobenzoic acid. The reaction can be given as:

Reaction (c)

(d) The compound,1-phenylethanol reacts with and to form acetophenone. This further reacts with and to form 2-Phenyl-2-propanol. The reaction can be given as:

Reaction (d)