Electrophilic Aromatic Substitution (Haloalkanes and Haloarenes) MCQ Questions & Answers in Organic Chemistry | Chemistry
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121.
Reaction of $$trans$$ -2-phenyl-1-bromocyclopentane on reaction with alcoholic $$KOH$$ produces
A
4-phenylcyclopentene
B
2-phenylcyclopentene
C
1-phenylcyclopentene
D
3-phenylcyclopentene
Answer :
3-phenylcyclopentene
It follows $$E2$$ mechanism.
122.
Which of the following statements is wrong ?
A
Ethyl chloride on reduction with $$Zn-Cu$$ couple and alcohol gives ethane.
B
The reaction of methyl magnesium bromide with acetone gives butanol-2.
C
Alkyl halides follow the following reactivity sequence on reaction with alkenes.
$$R - I > R - Br > R - Cl > R - I$$
D
$${C_2}{H_4}C{l_2}$$ may exist in two isomeric forms.
Answer :
The reaction of methyl magnesium bromide with acetone gives butanol-2.
123.
Chlorobenzene on treatment with sodium in dry ether gives diphenyl. The name of the reaction is
A
Fittig reaction
B
Wurtz-Fittig reaction
C
Sandmeyer reaction
D
Gattermann reaction
Answer :
Fittig reaction
124.
2-phenyl-2-hexanol can be prepared by Grignard synthesis. The pair of compounds giving the desired product is
A
B
C
D
Answer :
125.
What should be the correct IUPAC name for diethylbromomethane?
A
1-Bromo-1, 1-diethylmethane
B
3-Bromopentane
C
1-Bromo-1-ethylpropane
D
1-Bromopentane
Answer :
3-Bromopentane
No explanation is given for this question. Let's discuss the answer together.
126.
The order of reactivity of various alkyl halides towards nucleophilic substitution follows the order
A
$$R - I > R - Br > R - Cl > R - F$$
B
$$R - F > R - Cl > R - Br > R - I$$
C
$$R - Cl > R - Br > R - I > R - F$$
D
$$R - Br > R - I > R - Cl > R - F$$
Answer :
$$R - I > R - Br > R - Cl > R - F$$
The alkyl halides are very reactive due to highly polarised $$C -X$$ bond with a large difference in electronegativities of carbon and halogen atoms. The order of reactivity is iodides > bromides > chlorides > fluorides.
127.
$$A$$ compound $$A$$ with molecular formula $${C_{10}}{H_{13}}Cl$$ gives a white precipitate on adding silver nitrate solution. $$A$$ on reacting with alcoholic $$KOH$$ gives compound $$B$$ as the main product. $$B$$ on ozonolysis gives $$C$$ and $$D.$$ $$C$$ gives Cannizaro reaction but not aldol condensation. $$D$$ gives aldol condensation but not Cannizaro reaction.
$$A$$ is :
A
B
C
D
Answer :
Compound $$A$$ reacts with $$alc.KOH$$ to give compound $$B$$ which on further ozonolysis gives $$C$$ ( does not contains $$\alpha - H$$ atom ) and $$D$$ ( contains $$\alpha - H$$ atom ). This reaction sequence can be achieved by compounds in option (A) and (C). Since compound $$A$$ gives white $$ppt.$$ with $$AgN{O_3}$$ preferable option will be (C) as tert alkyl reacts with $$AgN{O_3}$$ more quickly.
128.
Primary alkyl halide, $${C_4}{H_9}Br\left( X \right)$$ reacts with alc. $$KOH$$ to give compound $$(Y).$$ $$(Y)$$ reacts with $$HBr$$ to give compound $$(Z)$$ which is an isomer of $$(X).$$ When $$(X)$$ reacts with $$Na$$ metal it gives compounds $$(P).$$ $$(X), (Y), (Z)$$ and $$(P)$$ are
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(a)
129.
Which of the following reacts at the fast rate with $$C{H_3}OK$$ in $$C{H_3}OH?$$
A
B
C
D
Answer :
The electron withdrawing nitro groups weaken the $$C – F$$ bond by inductive effect and resonance.
130.
Chlorobenzene is formed by reaction of chlorine with benzene in the presence of $$AlC{l_3}.$$ Which of the following species attacks the benzene ring in this reaction?
A
$$C{l^ - }$$
B
$$C{l^ + }$$
C
$$AlC{l_3}$$
D
$${\left[ {AlC{l_4}} \right]^ - }$$
Answer :
$$C{l^ + }$$
During chlorination of benzene, anhydrous $$AlC{l_3},$$ being a Lewis acid helps in generation of the electrophile $$C{l^ + }$$ by combining with the attacking reagent.
The electrophile $$C{l^ + }$$ attacks the benzene ring in this reaction.