Haloalkanes and Haloarenes Test

Result

Haloalkanes and Haloarenes Test - 32

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Weekly Quiz Competition

Question 1
1 / -0

The first steps of $${SN}^{1}$$ and $${SN}^{2}$$ reactions are, respectively:

A
Both exothermic

B
Both endothermic

C
Endothermic and exothermic

D
Exothermic and endothermic

Solution

In $${SN}_{2}$$, there is only one step, and it is exothermic. But in $${SN}_{1}$$ there are two steps first step; is endothermic and second step is exothermic.
Question 2
1 / -0

Which one of the following compounds gives $${S_N}{1}, {S_N}{2}$$ and $${S_N}{2'}$$ mechanisms?

A

B

C

D

Solution

Allyl halides undergo $${SN}^{1}, {SN}^{2}$$ and $${SN}^{2'}$$
Question 3
1 / -0

Nitration of xylene gives only one mono-nitro derivative. Which xylene is it?

A
ortho

B
meta

C
para

D
Both o and p

Solution

Nitration of para xylene gives only one mono-nitro derivative.
Nitration of ortho xylene gives two mono-nitro derivative.
Nitration of meta xylene gives three mono-nitro derivative.
Question 4
1 / -0

By which mechanism does the above reaction proceed?

A
$$E_1$$

B
$$E_2$$

C
$$E_1cb$$

D
$$\gamma$$-Elimination

Solution

If the reaction proceeds by $$E_1$$ mechanism, then the breaking of $$C-H$$ and $$C-D$$ bonds is not involved in the slow step (or rate determining effect). Based on this both products $$\displaystyle CH_2=CH-CD_3$$ and $$\displaystyle CH_3-CH=CD_2 $$ are expected. However only $$\displaystyle CH_2=CH-CD_3$$ is obtained. This indicates that breaking of $$C-H$$ bond (which is faster than breaking of $$C-D$$ bond) is involved in the mechanism along-with breaking of $$C-Br$$ bond. This indicates $$E_2$$ mechanism for elimination.
Question 5
1 / -0

The chemical reaction:
$${ \left( { CH }_{ 3 } \right) }_{ 3 } CBr \xrightarrow [ { -H }_{ 2 }O,-KBr ]{ KOH(alc.) } { \left( { CH }_{ 3 } \right) }_{ 2 }C={CH}_{2}$$ is an example of:

A
nucleophilic substitution

B
electrophilic substitution

C
free radical substitution

D
$$\beta$$-elimination
Question 6
1 / -0

$${C}_{3}{H}_{7}Cl \xrightarrow [ ]{ KOH(alc.) } (A) \xrightarrow [ 770K ]{ { Cl }_{ 2 }(g) } (X)$$. $$(X)$$ can be:

A
vinyl chloirde

B
allyl chloride

C
ethyl chloride

D
ethyl iodide

Solution

$$(A)\Rightarrow {CH}_{3}-CH={CH}_{2}$$
$$(X)\Rightarrow$$ Allylic chlorination
$$Cl-{CH}_{2}-CH={CH}_{2}$$
Allyl chloride
Question 7
1 / -0

$$\underset { Specific\quad rotaion=+{ 50 }^{ o } }{ Ph-CH(OH){ CH }_{ 3 } } \xrightarrow [ ]{ SO{ Cl }_{ 2 } } \quad \underset { |\\ Cl }{ PhCl } -{ CH }_{ 3 }$$
Which of the following mechanisms does the reaction proceed?

A
$${S_N}i$$

B
$${S_N}^{2}$$

C
$${S_N}^{1}$$

D
$$E_2$$

Solution

The reaction proceeds through $$SN^1$$ mechanism. The $$-OH$$ group of optically active substrate is replaced with $$-Cl$$ atom to form racemic mixture as the specific rotation of substrate is mentioned but that of product is not mentioned.
Question 8
1 / -0

Ethanol $$\xrightarrow [ ]{ { P }_{ 4 }/{ I }_{ 2 } } (X) \xrightarrow [ (ii)HBr ]{ (i)KOH(alc.) } (Y)$$
In this sequence of reaction , $$(Y)$$ is:

A
ethene

B
bromoethane

C
ethanol

D
none of these

Solution

In first step ethyl alcohol reacts with iodine and undergoes substitution reaction to form ethyl iodide. The ethyl iodide reacts with alcoholic KOH and undergoes elimination reaction to form ethylene which further reacts with HBr to form ethyl bromide.
Question 9
1 / -0

$${C}_{6}{H}_{5}Cl \xrightarrow [ 625K, \ 300atm ]{ NaOH(aq.) } $$
The product can be:

A
benzal

B
sodium benzoate

C
benzol

D
sodium phenate

Solution

$$PhCl\xrightarrow [ High\:temp.\: and\:pressure ]{ NaOH } \: \underset { Sodium\:Phenate }{ PhONa } $$
Question 10
1 / -0

Which of the following is called Westron?

A
$${CH}_{3}Cl$$

B
$$CH{Cl}_{3}$$

C
$$CH{Cl}_{2}.CH{Cl}_{2}$$

D
$$C{Cl}_{2}=CHCl$$

Solution

$$CH\equiv CH+2{Cl}_{2}\xrightarrow [ ]{ C{ Cl }_{ 4 } } \underset { Westron\: or\\ 1,1,2,2-Tetrachloro\: ethane\: or\\ Acetylene\: tetrachloride }{ C{ l }_{ 2 }-CH-CH-C{ l }_{ 2 } } $$
Westron is used as industrial solvent for rubber, fats and varnishes. It has some insecticidal action.