Phenolic group can be identified by a positive: [2024]
Phthalein dye test
Lucas test
Tollen's test
Carbylamine test
(1)
Phthalein dye test is a test for phenolic group. For example phenol condense with phthalic anhydride in the presence of concentrated to give phenolphthalein which gives a dark pink color with NaOH solution.
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R:
Assertion A: Aryl halides cannot be prepared by replacement of hydroxyl group of phenol by halogen atom.
Reason R: Phenols react with halogen acids violently.
In the light of the above statements, choose the most appropriate from the options given below: [2024]
A is false but R is true
Both A and R are true and R is the correct explanation of A
A is true but R is false
Both A and R are true but R is NOT the correct explanation of A
(3)
Due to resonance, there is partial double bond character in O-H bond of phenol. This makes the O-H bond difficult to break. Hence it does not react with halogen acids to give aryl halides.
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R:
Assertion A: value of phenol is 10.0 while that of ethanol is 15.9.
Reason R: Ethanol is stronger acid than phenol.
In the light of the above statements, choose the correct answer from the options given below: [2024]
A is true but R is false.
Both A and R are true but R is NOT the correct explanation of A.
Both A and R are true and R is the correct explanation of A.
A is false but R is true.
(1)
Phenols are stronger acids than alcohols because phenoxide ion is resonance stabilised whereas there is no resonance in alkoxide ion.
Given below are two statements:
Statement I: Bromination of phenol in solvent with low polarity such as or requires Lewis acid catalyst.
Statement II: The Lewis acid catalyst polarises the bromine to generate .
In the light of the above statements, choose the correct answer from the options given below: [2024]
Statement I is true but Statement II is false.
Both Statement I and Statement II are true.
Both Statement I and Statement II are false.
Statement I is false but Statement II is true.
(4)
The usual halogenation of benzene takes place in the presence of a Lewis acid, such as , which polarises the halogen molecule. In case of phenol, the polarisation of bromine molecule takes place even in the absence of Lewis acid. It is due to the highly activating effect of –OH group attached to the benzene ring, due to which charge density on ring increases and polarization of occurs even in absence of Lewis acid.
Match List - I with List - II [2024]
Choose the correct answer from the options given below:
(A)-(IV), (B)-(I), (C)-(III), (D)-(II)
(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
(A)-(II), (B)-(I), (C)-(III), (D)-(IV)
(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
(4)
(A) Kolbe reaction in presence of NaOH; and HCl.
(B) Reimer-Tiemann reaction
(C) Oxidation of phenol
(D) Williamson ether synthesis
Phenol treated with chloroform in the presence of sodium hydroxide, which is further hydrolyzed in the presence of an acid, results in [2024]
Benzene-1,2-diol
Benzene-1,3-diol
2-Hydroxybenzaldehyde
Salicylic acid
(3)
This is Reimer-Tiemann formylation reaction. The product is 2-hydroxybenzaldehyde (salicylaldehyde).
Salicylaldehyde is synthesized from phenol, when reacted with. [2024]
(4)
1. Formyl chloride (HCOCl) is unstable and does not exist, hence it cannot be used as a reagent.
2. This is Kolbe's reaction.
3. This is Reimer-Tiemann carboxylation reaction.
4. This is Reimer-Tiemann formylation reaction.
Match List - I with List - II. [2024]
| List - I (Reactants) | List - II (Products) | ||
| (A) | Phenol, | (I) | Salicylaldehyde |
| (B) | Phenol, | (II) | Salicylic acid |
| (C) | Phenol, | (III) | Benzene |
| (D) | (IV) | Picric acid |
Choose the correct answer from the options given below:
(A)-(IV), (B)-(I), (C)-(II), (D)-(III)
(A)-(III), (B)-(I), (C)-(II), (D)-(IV)
(A)-(IV), (B)-(II), (C)-(I), (D)-(III)
(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
(2)
(B) This is Reimer-Tiemann formylation reaction
(C) This is Kolbe’s reaction
(D) Nitration of phenol
Which one of the following reactions is NOT possible? [2024]
(3)
Given below are two statements: [2024]
Statement I: Picric acid is 2, 4, 6 - trinitrotoluene.
Statement II: Phenol - 2, 4 - disulphonic acid is treated with Conc. to get picric acid.
In the light of the above statements, choose the most appropriate answer from the options given below:
Both Statement I and Statement II are incorrect
Statement I is correct but Statement II is incorrect
Both Statement I and Statement II are correct
Statement I is incorrect but Statement II is correct
(4)
Picric acid is prepared by treating phenol first with concentrated sulphuric acid which converts it to phenol-2,4-disulphonic acid. Because of the –M effect of the group, electron density on the ring decreases and hence ring is less prone to getting oxidized. Phenol-2,4-disulphonic acid is then treated with concentrated nitric acid to get 2, 4, 6-trinitrophenol.
