Alcohols Phenols and Ethers Test

Result

Alcohols Phenols and Ethers Test - 18

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Weekly Quiz Competition

Question 1
1 / -0

Phenol is less acidic than __________.

A
ethanol

B
o-nitrophenol

C
o-methylphenol

D
o-methoxyphenol

Solution

In substituted phenols, the presence of electron withdrawing group such as nitro group, enhances the acidic strength of phenol. This effect is more pronounced when such a group is present at ortho and para positons. It is due to the effective delocalisation of negative charge in phenoxide ion. On the other hand, electron releasing groups, such as alkyl groups, in general, do not favour the formation of phenoxide ion resulting in decrease in acid strength. Cresols, for example, are less acidic than phenol.
Question 2
1 / -0

Which of the following is most acidic?

A
Benzyl alcohol

B
Cyclohexanol

C
Phenol

D
m-Chlorophenol

Solution

m-chlorophenol is most acidic. Alpha carbon of benzyl alcohol and cyclohexanol is \(sp^3\) hybridized. In m-chlorophenol, it is \(sp^2\) hybridized. In m-chlorophenol, electron withdrawing group —Cl is present at meta position.
Question 3
1 / -0

Arrange the following compounds in increasing order of boiling point.

Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol

A
Propan-1-ol, butan-2-ol, butan-1-ol, pentan-1-ol

B
Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol

C
Pentan-1-ol, butan-2-ol, butan-1-ol, propan-1-ol

D
Pentan-1-ol, butan-1-ol, butan-2-ol, propan-1-ol

Solution

The boiling points of alcohols and phenols increase with increase in the number of carbon atoms (increase in van der Waals forces.). In alcohols, the boiling points decrease with increase of branching in carbon chain (because of decrease in van der Waals forces with decrease in surface area.)

Question 4

1 / -0

Match the items of column I with items of column II.

Column I	Column II
(i) Antifreeze used in car engine	(a) Neutral ferric chloride
(ii) Solvent used in perfumes	(b) Glycerol
(iii) Starting material for picric acid	(c) Methanol
(iv) Wood spirit	(d) Phenol
(v) Reagent used for detection of phenolic group	(e) Ethleneglycol
(vi) By product of soap industry used in cosmetics	(f) Ethanol

(i)- (e) (ii)- (f) (iii)- (d) (iv)- (c) (v)- (a) (vi)- (b)

(i)- (c) (ii)- (f) (iii)- (d) (iv)- (f) (v)- (a) (vi)- (b)

(i)- (e) (ii)- (f) (iii)- (b) (iv)- (c) (v)- (a) (vi)- (d)

(i)- (e) (ii)- (a) (iii)- (d) (iv)- (c) (v)- (f) (vi)- (b)

Solution

(i) Ethleneglycol (IUPAC name of ethylene glycol is ethane-1,2-diol a small percentage of it is used in antifreeze formulation)

(ii) Ethanol (it is less irritating to skin so it is used in perfumes)

(iii) Phenol (by the reaction of phenol with conc. \(HNO_3\) phenol can be converted into picric acid)

(iv) Methanol (methanol is known as wood spirit as it was obtained by destructive distillation of wood)

(v) Neutral ferric chloride (Neutral ferric chloride gives violet colour when treated with phenol)

(vi) Glycerol (it is the by product in soap industry and is used in cosmetics)

Question 5

1 / -0

Match the items of column I with items of column II.

Column I	Column II
(i) Methanol	(a) Conversion of phenol to o-hydroxysalicylic acid
(ii) Kolbe’s reaction	(b) Ethyl alcohol
(iii) Williamson’s synthesis	(c) Conversion of phenol to salicylaldehyde
(iv) Conversion of 2° alcohol to ketone	(d) Wood spirit
(v) Reimer-Tiemann reaction	(e) Heated copper at 573K
(vi) Fermentation	(f) Reaction of alkyl halide with sodium alkoxide

(i)- (d) (ii)- (a) (iii)- (f) (iv)- (e) (v)- (c) (vi)- (b)

(i)- (d) (ii)- (e) (iii)- (f) (iv)- (a) (v)- (c) (vi)- (b)

(i)- (b) (ii)- (a) (iii)- (f) (iv)- (e) (v)- (c) (vi)- (d)

(i)- (d) (ii)- (c) (iii)- (e) (iv)- (f) (v)- (a) (vi)- (b)

Solution

(i) Methanol Wood spirit (methanol is known as wood spirit as it was obtained by destructive distillation of wood).

(ii) Kolbe’s reaction Conversion of phenol to ortho-hydroxyl salicylic acid (reaction of phenol with \(CO_2\) gas gives ortho-hydroxy salicylic acid)

(iii) Williamson’ synthesis → Reaction of alkyl halide with sodium alkoxide (Reaction of alkyl halide with sodium alkoxide gives ether. It is a very important method for the preparation of ether)

(iv) Conversion of 2° alcohol to ketone → Heated copper at 573 K (by dehydrogenation of secondary alcohol it is converted into ketone).

(v) Reimer-Tiemann reaction → Conversion of phenol to salicylaldehyde (phenol is treated with chloroform in presence of NaOH and salicylaldehyde is formed as the product)

(vi) Fermentation → Ethyl alcohol (ethanol is prepared by the fermentation of sugar).