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Using anhydrous $AlCl_3$ as catalyst, which one of the following reactions produces ethylbenzene (PhEt) :-
A
$CH_3-CH=CH_2 + C_6H_6$
B
$H_2C=CH_2 + C_6H_6$
C
$H_3C-CH_3 + C_6H_6$
D
$H_3C-CH_2OH + C_6H_6$
Detailed Solution
Ethylbenzene, $C_6H_5CH_2CH_3$, needs an ethyl group to be attached to the benzene ring.
Ethylene in the presence of $AlCl_3$ (with a trace of HCl) gives the ethyl carbocation, $CH_3CH_2^+$, which attacks benzene (electrophilic substitution):
$CH_2=CH_2 + C_6H_6 \xrightarrow{anhyd.\ AlCl_3,\ HCl} C_6H_5CH_2CH_3$
This is the industrial method for making ethylbenzene (for styrene manufacture).
Propene would give the more stable isopropyl carbocation and so form isopropylbenzene (cumene), not ethylbenzene.
Ethane is a saturated alkane and does not produce a carbocation with $AlCl_3$. Ethanol reacts with and deactivates $AlCl_3$, so it is not used with this catalyst.
So ethylbenzene is produced from $H_2C=CH_2 + C_6H_6$.
Ethylene in the presence of $AlCl_3$ (with a trace of HCl) gives the ethyl carbocation, $CH_3CH_2^+$, which attacks benzene (electrophilic substitution):
$CH_2=CH_2 + C_6H_6 \xrightarrow{anhyd.\ AlCl_3,\ HCl} C_6H_5CH_2CH_3$
This is the industrial method for making ethylbenzene (for styrene manufacture).
Propene would give the more stable isopropyl carbocation and so form isopropylbenzene (cumene), not ethylbenzene.
Ethane is a saturated alkane and does not produce a carbocation with $AlCl_3$. Ethanol reacts with and deactivates $AlCl_3$, so it is not used with this catalyst.
So ethylbenzene is produced from $H_2C=CH_2 + C_6H_6$.