Alcohols Phenols and Ethers Test

Result

Alcohols Phenols and Ethers Test - 67

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following reactions will not yield phenol?

A

B

C

D

Solution

The reaction of option (D) will not yield phenol. It is nucleophilic substitution of chlorobenzene which requires drastic conditions (high temperature of 613 K and high pressure of 300 atm).

Note:
The following reactions will yield phenol

(A) Dow process: Chlorbenzene is heated with excess aq NaOH at 613 K and 300 atm. This is followed by hydrolysis with dil HCl.

(B) From aniline diazotization: Diazotization of aniline (with nitrous acid at 0-5 deg C) followed by warming with water gives phenol.

(C) From benzene sulphonic acid: Benzene is sulphonated with oleum to form benzene sulphonic acid. It is then heated with NaOH and then followed with acid hydrolysis.

Option D is correct answer.
Question 2
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Consider the following reaction sequence,

$$CH_3CH(OH)CH_3 \xrightarrow[Heat]{Conc.H_2SO_4} X
\xrightarrow[H_2O]{dil.H_2SO_4}Y$$

X and Y in the reaction respectively are :

A
$$CH_3CH = CH_2, CH_3CH(OH)CH_3$$

B
$$ CH_3CH = CHCH_3, CH_3CH_2CH_2OH$$

C
$$CH_3CH_2CH = CH_2,CH_3CH_2CH_2OH$$

D
$$CH_3CH_2CH_2CH_3, CH_3CH(OH)CH_2CH_3$$

Solution

$$CH_3 \underset {\underset {\displaystyle OH}{|}}{C}H-CH_3 \xrightarrow {Conc. H_2SO_4/Heat} \underset {(X)}{CH_3CH=CH_2} \xrightarrow {dil. H_2SO_4/H_2O} \underset {(Y)}{CH_3 \underset {\underset {\displaystyle OH}{|}}{C}H-CH_3}$$
Question 3
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What happens when tertiary butyl alcohol is passed over heated copper at $$300^0$$C ?

A
Secondary butyl alcohol is formed.

B
2-Methylpropene is formed .

C
1-Butene is formed .

D
Butanal is formed.

Solution

Tertiary alcohol when passed over $$Cu$$ at $$300^{\circ}C$$ is dehydrated to alkene.
$$CH_{ 3 }-{ \underset { \underset { C{ H }_{ 3 } }{ | } }{ \overset { \overset { C{ H }_{ 3 } }{ | } }{ C } } }-OH\ \overset { Cu,\ 300^{ 0 }C }{ \longrightarrow } CH_{ 3 }-{ \underset { \underset { C{ H }_{ 3 } }{ | } }{ \overset { \overset { C{ H }_{ 2 } }{ || } }{ C } } }$$
$$t-butyl\ alcohol \overset { Cu,\ 300^{ 0 }C }{ \longrightarrow } 2-methyl\ propene$$
Question 4
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The ease of dehydration in the following compounds is:

A
$$I > III > IV > II$$

B
$$II > I > III > IV$$

C
$$IV > I > III > II$$

D
$$III > I > II > IV$$

Solution
Question 5
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Major product obtained in the reaction is :

A

B

C

D

Solution

The carbocation formed adjacent to double bond is more stable.
(Refer to Image)
Question 6
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Compare rate of dehydration of (i), (ii), and (iii) by conc. $$H_2SO_4$$ .

A
(i) > (iii) > (ii)

B
(i) > (ii) > (iii)

C
(ii) > (i) > (iii)

D
(ii) > (iii) > (i)

Solution
Question 7
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Product (A) of the given reaction is?

A

B

C

D
Question 8
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Decreasing order of acidic strength of different (-OH) group is:

A
$$w > x > y > z$$

B
$$w > z > x > y$$

C
$$z > w > x > y$$

D
$$z > x > w > y$$

Solution

$$w$$ will be the most acidic, as the anion (formed after the proton is removed) is stabilized by resonance in benzene ring.
$$z$$ will be the least acidic as the anion formed will experience a significant $$+I$$ effect from the $$-CH_2$$ group adjacent to it, thus destabilizing it.
$$x$$ will be comparatively more acidic than $$y$$ as it experiences less $$
+I$$ effect to a less extent. Hence the order of acidic strength is:
$$w>x>y>z$$
Question 9
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A solution of $$Ph_{3}CCO_{2}H$$ in conc. $$H_{2}SO_{4}$$ gives $$(X)$$ when poured into methanol $$X$$ is :

A
$$Ph_3C-\overset{\overset{O}{||}}{C}-O-CH_3$$

B
$$Ph_2CH-\overset{\overset{O}{||}}{C}-O=CH_3$$

C
$$Ph_{3}C - OCH_{3}$$

D
$$Ph_{3}C - CH_{3}$$

Solution

$$Ph_3C-C-OOH+CH_3OH\xrightarrow []{conc.H_2SO_4}Ph_3C-OCH_3$$
Mechanism:-
$$Ph_3C^{\oplus}$$ is a stable carbocation whicch breaks replaces $$H^+$$ in $$CH_3OH$$ to give $$Ph_3C-OCH_3$$;
(Refer to Image)
Question 10
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Based on above isomers answer the following.
Which isomers on dehydration give most stable alkene?

A
a, b, g,

B
d, e, f, g, h

C
c,d, b, g

D
None of these

Solution