Question

Question: Show how the following compounds could be prepared from the given starting materials. You can use any necessary organic or inorganic reagents.

a.

b.

c.

d.

Short answer

Answer

a.

b.

c.

d.

Step-by-step solution

Conversion of propanamide to propanoyl chloride (a)

Propanamide cannot be directly converted to propanoyl chloride.It requires some processes. First propanamide undergoes hydrolysis in the presence of aqueous acid. This produces a carboxylic acid named propanoic acid.

Propanamide Propanoic acid

Now, propanoic acid is treated with thionyl chloride and , to form acid chloride, i.e., propanoyl chloride. Chloride anion is the nucleophile in this reaction.

The complete reaction is shown below.

Preparation of (a)

Conversion of butanol to butanoic acid (b)

Butanol is first converted to chlorobutane by adding thionyl chloride. It is followed by the addition of cyanide ion, sodium cyanide or potassium cyanide, to form pentanenitrile. This can be easily converted to carboxylic acid by hydrolysis. On hydrolysis, cyanide group is changed to carboxylic group. It also releases ammonium ion. The complete reaction is shown below.

Conversion of toluene to N-methylbenzamide (c)

Toluene can be converted to N-methyl benzamide through several processes. First, toluene is treated with chromic acid which acts as an oxidizing agent. It converts toluene to benzoic acid. Benzoic acid is then converted to benzoyl chloride by treating it with thionyl chloride. Benzoyl chloride is finally converted to N-methylbenzamide by adding it with methylamine in excess amount. The complete reaction is shown below.

Preparation of (c)

Conversion of toluene to 3-phenyl propanoic acid (d)

Toluene can be converted to 3-phenyl propanoic acid by heating it with N-bromosuccinimide, which is a source of , in the presence of peroxide, followed by adding potassium cyanide which undergoes hydrolysis. After this, N-bromosuccinimide gives bromomethyl benzene which is then added with cyanide ion. It gives phenyl aceto nitrile which then undergoe hydrolysis, thereby producing 3-phenyl propanoic acid. The complete reaction is shown below.

Preparation of (d)