What are aromatic ketones ? Discuss the prepration , properties and used of acetophenone.

 Aromatic Ketons :-

Those organic compound in which carbonyl group attached to aryl group or one alkyl and one aryl group  are called aromatic ketones.

Methods of Preparation of Acetophenone :-

1. Friedal-Crafts Methods - When benzene is heated with acetylchloride or acetic anhydride in presence of anhydrous AlCl₃ , Acetophenone is obtained .
   
2. By Catalytic Oxidation - When Ethyl benzene is oxidised by air or oxygen in presence of Magnes acetate at 120°C , Acetophenone is formed.
   

Physical Properties

• It is colourless liquid and has B. P. 240°C. 
• Ist is less soluble in H₂O but in alcohol and ether it is soluble.

Chemical Properties 

In Acetophenone, One methyl and one phenyl group atteched with carbonyl group. Hence it gives all aliphatic Ketones reaction.

Effect of -COCH₃ is m-directing. Hence it gives all electrophillic substitution reaction like benzene. Nucleophillic addition reaction of -COCH₃ are as follows-

• Addition of HCN-

Acetophidron give additional reaction with hydrocynic acid and form acetophenon cynohydrin.  

• Addition of Grignard's Reagent -

Acetophenon gives adduct with Grignard Reagent which gives tertiary alcohol on water hydrolysis.

• Reduction-

Acetophenon is reduced into Ethyl benzene by Zn-Hg pair and HCl. This reaction of reduction is called Clemensons Reaction.

• Oxidation-

Acetophenon is oxidised into benzoic acid by K₂Cr₂O₇ or KMnO₄.

•  Reaction with Phenyl Hydrazeine -

Acetophenon is condensed into Phenyl hydrazone with Phenyl hydrazene.

• Reaction with Hydroxyl Amine-

 Hydroxyl amine is condensed with aceto-phenone into methyl phenyl ketoxime which rearranged and give N- substituted amide by dilute acid or PCl₅. This reaction is know as Backmann rearrangment reaction.

• Iodoform Reaction-

Acetophenon reacts with Iodine and give Iodoform in presence of NaOH due to Methyl Ketone.

• Chlorination-

Acetophenon reacts with Cl₂ in presence AlCl₃ and give phencyl chloride.

• Aldol Type Condensation-

Acetophenon gives adduct in presence of Alumnium t-Butoxide. Which is called Diphon.

• Electrophillic Substitution Reaction-

Acetophenon gives nitration and sulphonation. Their product is m-directing by substitution reaction. Because nature of -COCH₃ group is m-directing.

1. When Acetophenon undergoes nitration by conc.HNO₃/conc.H₂SO₄ then m-nitroacetophenon.
   
2. Sulphonic Acid is obtained on sulphonation.
   
   
   

Use :-

• It is used in manufacturing of the perfumes.

• It is used in manufacturing of the sleeping pills.