Question

Convert benzaldehyde to benzophenone.

Answer 1

Hint: When we do the oxidation of aldehyde, it is converted into carboxylic acid. And then by decarboxylation it gets converted to aromatic hydrocarbon. Then if we treat it with benzoyl chloride, we get the desired result.

Step by step answer:
First, we should know about benzaldehyde. So, benzaldehyde (${{C}_{6}}{{H}_{5}}CHO$) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful.
We should know its physical properties that it is a colourless liquid with a characteristic almond-like odour. The primary component of bitter almond oil, benzaldehyde can be extracted from a number of other natural sources. We use synthetic benzaldehyde for flavoring cakes.
Now, we should know about benzoic acid. So, benzoic acid is a white (or colourless) solid with the formula ${{C}_{6}}{{H}_{5}}COOH$. We use benzoic acid most commonly in industrial settings to manufacture a wide variety of products such as perfumes, dyes, topical medications and insect repellents.
So, now we will focus on our question : the conversion of benzaldehyde to benzoic acid.

Benzaldehyde is oxidized in the presence of acidified potassium permanganate, it results in the formation of benzoic acid.

Then convert benzoic acid to benzene.

When we react benzoic acid with soda lime (mixture of NaOH and CaO) with heat, it results in the formation of benzene.

Then with the final step we will convert benzene to benzophenone.

When benzene is treated with benzoyl chloride in the presence of $AlC{{l}_{3}}$ it leads to the formation of benzophenone. This reaction is known as Friedel-Craft acylation.

Note: We should know about Friedel–Crafts reactions. These are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. Friedel–Crafts acylation involves the acylation of aromatic rings. We use typical acylating agents such as acyl chlorides.