Q30E - Organic Chemistry (Mcmurry)

Question

Predict the product(s) and provide the mechanism for each reaction below. What does each mechanism have in common?

Step-by-Step Solution

Answer

(a) 

(b) 

(c)

Step-by-Step Solution Step 1: Freidal craft acylation

Freidal craft acylation reaction is the “substitution of electrophile (acylium ion)” on the electron-rich benzene ring. The electrophile is generated by reacting the acetyl/acyl chloride with lewis acid aluminum chloride $\left({\text{AlCl}}_{\text{3}}\right)$.

 

The formation of “acylium ion” is common in all friedal craft acylation reactions.

Step 2: Friedal craft acylation of 3-phenylpropanoyl chloride

Reaction (a) is an intramolecular Friedel craft acylation reaction in which the acylium ion (electrophile) is generated within the reactant, which will attack the same reactant 3 - phenylpropanoyl chloride (nucleophile), leading to the formation 2,3-dihydro-1H-inden-1-one.

Formation of 2,3-dihydro-1H-inden-1-one

Step 3: Freidal craft acylation of Anisole

Reaction (b) is friedal craft acylation in which the acetyl chloride reacts with a lewis acid $\left({\text{AlCl}}_{\text{3}}\right)$ to form the acylium ion (electrophile), which attacks the reactant anisole (nucleophile), which is meta directing group, resulting in the attack of acylium group at the meta position, forming the product 1-(3-methoxyphenyl)ethenone.

Formation of 1-(3-methoxyphenyl)ethanone

Step 4: Freidal craft acylation of (c)

Reaction (c) is friedal craft acylation in which propanoyl chloride reacts with a lewis acid $\left({\text{AlCl}}_{\text{3}}\right)$ to form the acylium ion (electrophile), which attacks the reactant  tert-butylbenzene  (nucleophile), which is ortho, para directing group, resulting in the attack of acylium group at the ortho and para position, forming the two products: 

• Para product formed is 1-(4-tert-butylphenyl)propan-1-one
• Ortho product is 1-(2-tert-butylphenyl)propan-1-one

Formation of para and ortho product