Question

1a. The pi bond in benzene reacts with a ____ to form a ____ intermediate. This intermediate undergoes a ___ reaction to form the substituted benzene. nucleophile electrophile radical carbocation carbanion substitution elimination acid-base 1b. Benzene reacts with HNO3/H2SO4 to form: benzene sulfonic acid nitrobenzene no reaction 1c. Benzene reacts with 1-chloropropane/AlCl3 to form: chlorobenzene propylbenzene isopropylbenzene (also called cumene) 1d. Benzene reacts with acetyl chloride (CH3COCl)/AlCl3 to form: chlorobenzene acetophenone (also called methylphenylketone) ethylbenzene 1e. Styrene reacts with HBr/peroxides to produce Compound A. Compound A reacts with CH3MgBr to make ____.

Answer 1

1a) The pi bond of benzene react with AN ELECTROPHILE to form a CARBOCATION intermediate. This intermediate undergo an ELIMINATION reaction to form the substituted benzene.

The above explanation is for an Aromatic electrophilic substitution reaction. The very general mechanism is shown here to understand how the reaction is all about. This help in understanding above filling the blanks.

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1b) Benzene react with HNO3/H2SO4 i.e a nitrating mixture to form Nitrobenzene compound.

Mechanism: HNO3 + H2SO4 ------------> NO2⁺ + HSO4_- + H2O.

NO2+ a nitronium ion is stron electrophile which get radilly attake pi electron system of benzene forming nitrobenzene following the mechanism explained in 1a).

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1c) Benzene react with 1-chloropropane/AlCl3 to form Isopropylbenzene (Cumene) as major compound(thermodynamic product) and n-Propylbenzene as minor product( Kinetic product).

The mechanism:

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1d) Benzene react with acetyl chloride (CH3COCl/AlCl3) to form compound Acetophenone

(Methylphenylketone) .

Mechanism

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1e) Styrene react with HBr/peroxide to produce1-Bromo-1-phenylethane (A).

The reaction folows radical mechanism. The addition of HBr follows anti-Markovnikoff's addition rule and this is also known as Kharasch-Mayo effect.

Mechanism

The product 1-Bromo-1-phenylethane do not react with grignard reagent CH3MgBr.