Electrophilic Aromatic Substitution (Haloalkanes and Haloarenes) MCQ Questions & Answers in Organic Chemistry | Chemistry
Learn Electrophilic Aromatic Substitution (Haloalkanes and Haloarenes) MCQ questions & answers in Organic Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
41.
\[{{C}_{8}}{{H}_{8}}C{{l}_{2}}\left( A \right)\xrightarrow{Aq.\,NaOH}\left( B \right)\] \[\xrightarrow{\text{Mild reduction}}\left( C \right)\xrightarrow{\frac{{{I}_{2}}}{NaOH}}\] \[\text{iodoform + acid salt }\left( D \right)\]
In the given sequence of reaction, what would be the structure of $$(A)?$$
A
$$PhCOC{H_3}$$
B
$$PhCH\left( {OH} \right)C{H_3}$$
C
$$PhCOONa$$
D
$$PhC{\left( {Cl} \right)_2}C{H_3}$$
Answer :
$$PhC{\left( {Cl} \right)_2}C{H_3}$$
Overall reactions can be represented as :
42.
Toluene reacts with a halogen in the presence of iron (III) chloride giving $$ortho$$ and $$para$$ halo compounds. The reaction is
A
electrophilic elimination reaction
B
electrophilic substitution reaction
C
free radical addition reaction
D
nucleophilic substitution reaction
Answer :
electrophilic substitution reaction
The reaction is electrophilic substitution reaction.
43.
$$36.4\,g$$ of 1, 1, 2, 2-tetrachloropropane was heated with zinc dust and the product was bubbled through ammoniacal $$AgN{O_3}.$$ What is the weight of precipitate obtained?
A
30.0 $$g$$
B
29.4 $$g$$
C
28.0 $$g$$
D
25.7 $$g$$
Answer :
29.4 $$g$$
The dehalogenation of vicinal tetrahaloalkane gives alkynes. It is done by heating the compound with $$Zn$$ dust.
\[\underset{\begin{smallmatrix}
\text{1, 1, 2, 2-tetrachloropropane} \\
\text{Molecular weight = 182 }
\end{smallmatrix}}{\mathop{C{{H}_{3}}\underset{\begin{smallmatrix}
| \\
Cl\,
\end{smallmatrix}}{\overset{\begin{smallmatrix}
\,Cl \\
|
\end{smallmatrix}}{\mathop{-\,\,C\,\,-}}}\,\underset{\begin{smallmatrix}
|\,\,\,\,\,\, \\
Cl\,\,\,\,\,\,
\end{smallmatrix}}{\overset{\begin{smallmatrix}
Cl\,\,\, \\
|\,\,\,\,\,
\end{smallmatrix}}{\mathop{CH}}}\,\xrightarrow{Zn/\Delta }}}\,\] \[\underset{\text{Propyne}}{\mathop{C{{H}_{3}}-C\equiv C-H}}\,\]
\[C{{H}_{3}}C\equiv C-H+AgN{{O}_{3}}\xrightarrow[\Delta ]{N{{H}_{4}}OH}\] \[\underset{\begin{smallmatrix}
\text{Silver propynide (ppt}\text{.)} \\
\left( Mol.\,wt\text{ }=\text{ }147 \right)
\end{smallmatrix}}{\mathop{C{{H}_{3}}-C\equiv C-Ag}}\,+N{{H}_{4}}N{{O}_{3}}+{{H}_{2}}O\]
\[\because \,182\,g\] of tetrachloro alkane gives \[147\,g\] of ppt.
\[\therefore \,36.4\,g\] tetrachloro alkane gives \[\frac{147\times 36.4}{182}=29.4\,g\] of precipitate
44.
Triiodomethane has antiseptic property because of
A
liberation of iodoform
B
liberation of free iodine
C
formation of phosgene gas
D
none of these
Answer :
liberation of free iodine
Triiodomethane (iodoform) has antiseptic property due to the liberation of free iodine and not due to iodoform itself.
50.
Chlorobenzene can be converted into phenol by heating in aqueous sodium hydroxide solution at a temperature of $$623\,K$$ and a pressure of $$300\,atm.$$ However the rate of reaction can be increased by presence of certain groups in benzene ring. What will be the order of reactivity of following compounds towards the above substitution reaction?
A
(iii) > (ii) > (i)
B
(ii) > (iii) > (i)
C
(i) > (ii) > (iii)
D
(i) > (iii) > (ii)
Answer :
(iii) > (ii) > (i)
The presence of an electron withdrawing group $$\left( { - N{O_2}} \right)$$ at $$ortho$$ and $$para$$ - positions increases the reactivity of haloarenes.