Question

Question: How can you prepare the following compounds with benzene as one of the starting materials?

a.)

b.)

c.)

d.)

Short answer

a.)

b)

c.)

d.)

Step-by-step solution

Friedel-Crafts Acylation

Friedel-crafts acylation is an organic chemical reaction which involves the addition of an acyl group to an aromatic ring. In this reaction we use a mixture of acid chloride and catalyst AlCl₃to covert aromatic ring in to a ketone.

Synthesis of compound (a) and (b)

(a) In the first step, there is a treatment of benzene with bromine in the presence of catalyst FeBr₃to form bromobenzene, which undergoes reaction with phenylboronic acid in the presence of PdL₂in basic medium to produce our desired product (biphenyl) as shown in figure given below:

Synthesis of (a)

(b) This reaction undergoes Friedel-Crafts acylation to form the desired product as shown below:

Synthesis of (b)

Synthesis of compound (c) and (d)

Cyclic compounds are formed from intramolecular reactions. It is a type of reactions in which the two reacting groups are in the same molecule. We know that intramolecularre actions are particularly favored if the reaction forms a compound with a five- or a six-membered ring.

In this reaction a diketone is formed from the Friedel–Crafts acylation of a benzene ring. The size of the ring is determined by the number of carbons between the two reacting groups.

c.)

Synthesis of (c)

(d) In the first step, starting material benzene react with sulphuric acid to form benzenesulphonic acid which on further undergoes bromination and react with strong base and acid to form a desired product as diols as shown in the figure given below:

Synthesis of (d)