In: Chemistry
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.