Aldehyde, Ketones and Carboxylic Acids
Multiple Choice Questions (MCQs)
1. Addition of water to alkynes occurs in acidic medium and in the presence of
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Answer
(b) But-1-yne on reaction with water in presence of
Mechanism
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Option (a): This option suggests the formation of butan-1-one. However, the hydration of but-1-yne in the presence of
ions follows Markovnikov’s rule, leading to the formation of a more stable ketone, which is butan-2-one, not butan-1-one. -
Option (c): This option suggests the formation of butan-1-ol. The hydration of alkynes in the presence of
ions does not produce alcohols directly. Instead, it forms ketones or aldehydes depending on the structure of the alkyne. -
Option (d): This option suggests the formation of butan-2-ol. Similar to option (c), the hydration of alkynes in the presence of
ions does not produce alcohols directly. The reaction mechanism leads to the formation of a ketone, specifically butan-2-one in this case.
2. Which of the following compounds is most reactive towards nucleophilic addition reactions?
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Answer
(a) Reactivity of carbonyl compounds can be decided by two factors
(i) Steric factor Lesser the steric factor greater will be its reactivity.
(ii) Electronic factor Greater the number of alkyl group lesser will be its electrophilicity.
Hence,
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Option (b): The presence of two alkyl groups (ethyl groups) increases the steric hindrance around the carbonyl carbon, making it less accessible to nucleophiles. Additionally, the electron-donating effect of the alkyl groups reduces the electrophilicity of the carbonyl carbon, making it less reactive towards nucleophilic addition.
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Option (c): The presence of a phenyl group (benzene ring) attached to the carbonyl carbon significantly reduces its reactivity towards nucleophilic addition. The phenyl group is bulky, increasing steric hindrance, and it also has a resonance effect that delocalizes the positive charge on the carbonyl carbon, reducing its electrophilicity.
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Option (d): The presence of two phenyl groups (benzene rings) attached to the carbonyl carbon greatly reduces its reactivity towards nucleophilic addition. The steric hindrance is significantly increased due to the bulkiness of the phenyl groups. Additionally, the resonance effect from both phenyl groups further delocalizes the positive charge on the carbonyl carbon, making it much less electrophilic.
3. The correct order of increasing acidic strength is….. .
(a) phenol
(b) ethanol
(c) ethanol
(d) chloroacetic acid
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Answer
(c) Phenol is more stable than alcohol due to formation of more stable conjugate base after removal of
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On the other hand, carboxylic acid is more acidic than phenol due to formation of more stable conjugate base after removal of
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Chloroacetic acid is more acidic than acetic acid due to the presence of electron withdrawing chlorine group attached to
Hence, correct choice is (c).
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Option (a): Phenol is more acidic than ethanol because the phenoxide ion formed after deprotonation of phenol is resonance-stabilized, whereas the ethoxide ion formed from ethanol is not. Additionally, chloroacetic acid is more acidic than acetic acid due to the electron-withdrawing effect of the chlorine atom, which stabilizes the conjugate base. Therefore, the order given in option (a) is incorrect.
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Option (b): Acetic acid is less acidic than chloroacetic acid because the electron-withdrawing chlorine atom in chloroacetic acid stabilizes the conjugate base more effectively than the hydrogen atom in acetic acid. Therefore, the order given in option (b) is incorrect.
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Option (d): Ethanol is the least acidic among the given compounds because its conjugate base (ethoxide ion) is not stabilized by resonance or electron-withdrawing groups. Phenol is more acidic than ethanol due to resonance stabilization of the phenoxide ion. Acetic acid is more acidic than phenol because the carboxylate ion is stabilized by resonance. Chloroacetic acid is the most acidic due to the electron-withdrawing chlorine atom. Therefore, the order given in option (d) is incorrect.
4. Compound
(a) phenol and benzoic acid in the presence of
(b) phenol and benzoyl chloride in the presence of pyridine
(c) phenol and benzoyl chloride in the presence of
(d) phenol and benzaldehyde in the presence of palladium
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Answer
(b) Compound
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This is an example of Schotten-Baumann reaction.
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(a) phenol and benzoic acid in the presence of
: This reaction would not produce the desired compound because benzoic acid and phenol in the presence of NaOH would lead to the formation of the phenoxide ion and the benzoate ion, but not the ester . Esterification typically requires an acid catalyst, not a base like NaOH. -
(c) phenol and benzoyl chloride in the presence of
: While benzoyl chloride is a correct reactant, $\mathrm{ZnCl}{2} \mathrm{ZnCl}{2}$ cannot do. -
(d) phenol and benzaldehyde in the presence of palladium: Benzaldehyde is not the correct reactant for forming the ester
. Benzaldehyde would more likely participate in reactions such as the Cannizzaro reaction or aldol condensation, but not in the formation of an ester with phenol.
5. The reagent which does not react with both, acetone and benzaldehyde?
(a) Sodium hydrogen sulphite
(b) Phenyl hydrazine
(c) Fehling’s solution
(d) Grignard reagent
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Answer
(c) Acetone and benzaldehyde both do not react with Fehling’s solution. Fehling’s solution react with ketone as acetone is an ketone while benzaldehyde is an aromatic aldehyde having absence of
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(a) Sodium hydrogen sulphite: Sodium hydrogen sulphite reacts with both acetone and benzaldehyde. It forms bisulfite addition compounds with carbonyl compounds, including both ketones and aldehydes.
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(b) Phenyl hydrazine: Phenyl hydrazine reacts with both acetone and benzaldehyde to form hydrazones. It reacts with the carbonyl group present in both compounds.
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(d) Grignard reagent: Grignard reagents react with both acetone and benzaldehyde. They add to the carbonyl group of ketones and aldehydes to form alcohols after hydrolysis.
6. Cannizzaro’s reaction is not given by…… .
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(c)
(d)
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Answer
(d) Necessary condition for Cannizzaro reaction is absence of
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(a)
: This compound, benzaldehyde, does not have any -hydrogen atoms, making it suitable for the Cannizzaro reaction. -
(b)
: Formaldehyde also lacks -hydrogen atoms, which makes it capable of undergoing the Cannizzaro reaction. -
(c)
: Chloroacetaldehyde does not have an -hydrogen atom, thus it can participate in the Cannizzaro reaction.
7. Which products is formed when the compound
is treated with concentrated aqueous
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Answer
(b) Benzaldehyde is an aromatic aldehyde having no
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Option (a) is incorrect because it suggests the formation of benzyl alcohol and benzoic acid. However, in the Cannizzaro reaction, the products are benzyl alcohol and potassium benzoate, not benzoic acid.
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Option (c) is incorrect because it suggests the formation of benzyl alcohol and benzaldehyde. In the Cannizzaro reaction, benzaldehyde is converted into benzyl alcohol and potassium benzoate, so benzaldehyde is not a final product.
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Option (d) is incorrect because it suggests the formation of benzyl alcohol and potassium benzoate along with another product. The Cannizzaro reaction specifically produces only benzyl alcohol and potassium benzoate as the final products.
8.
Structure of ’
(a) Prop-1-en-2-ol, metamerism
(b) Prop-1-en-1-ol, tautomerism
(c) Prop-2-en-2-ol, geometrical isomerism
(d) Prop-1-en-2-ol, tautomerism
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Answer
(d) Chemical reaction can be shown as
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(a) Prop-1-en-2-ol, metamerism: Metamerism is a type of isomerism where compounds have the same molecular formula but different alkyl groups on either side of a functional group. In this reaction, the isomerism involved is tautomerism, not metamerism.
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(b) Prop-1-en-1-ol, tautomerism: The structure of ‘A’ is not Prop-1-en-1-ol. The correct structure is Prop-1-en-2-ol. Therefore, this option is incorrect because it specifies the wrong structure.
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(c) Prop-2-en-2-ol, geometrical isomerism: The structure of ‘A’ is not Prop-2-en-2-ol. Additionally, the type of isomerism involved in the reaction is tautomerism, not geometrical isomerism.
9. Compounds
(a) identical
(b) positional isomers
(c) functional isomers
(d) optical isomers
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Answer
(b) Chemical reaction can be shown as
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Thus,
Hence, option (b) is correct.
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Option (a) identical: Compounds A and C are not identical because they have different structures. Compound A is 2-propanol (CH₃-CH(OH)-CH₃), while compound C is 1-propanol (CH₃-CH₂-CH₂OH). Identical compounds must have the same molecular structure and connectivity, which is not the case here.
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Option (c) functional isomers: Functional isomers have the same molecular formula but different functional groups. In this case, both compounds A and C are alcohols (they both contain the -OH group), so they are not functional isomers. They differ in the position of the -OH group, making them positional isomers instead.
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Option (d) optical isomers: Optical isomers (enantiomers) are non-superimposable mirror images of each other and typically occur in compounds with chiral centers. Neither compound A (2-propanol) nor compound C (1-propanol) has a chiral center, so they cannot be optical isomers.
10. Which is the most suitable reagent for the following conversion?
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(a) Tollen’s reagent
(b) Benzoyl peroxide
(c)
(d)
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Answer
(c) lodoform test is used to test presence of
The reaction is shown as
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Tollen’s reagent: Tollen’s reagent is used to test for the presence of aldehydes. It oxidizes aldehydes to carboxylic acids but does not react with ketones or the
group, making it unsuitable for this conversion. -
Benzoyl peroxide: Benzoyl peroxide is a radical initiator used in polymerization reactions and as an oxidizing agent. It does not specifically react with the
group to convert it into a group, making it unsuitable for this conversion. -
and solution: Tin (Sn) and sodium hydroxide (NaOH) are typically used in reduction reactions, such as the reduction of nitro groups to amines. They do not facilitate the conversion of the group to a group, making them unsuitable for this conversion.
11. Which of the following compounds will give butanone on oxidation with alkaline
(a) Butan-1-ol
(b) Butan-2-ol
(c) Both (a) and (b)
(d) None of these
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Answer
(b) Butan-2-ol on oxidation with alkaline
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Butan-1-ol: On oxidation with alkaline KMnO₄, butan-1-ol will not produce butanone. Instead, it will undergo oxidation to form butanoic acid. This is because primary alcohols are typically oxidized to carboxylic acids under these conditions.
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Both (a) and (b): This option is incorrect because, as mentioned, butan-1-ol does not produce butanone upon oxidation with alkaline KMnO₄. Only butan-2-ol produces butanone.
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None of these: This option is incorrect because butan-2-ol does indeed produce butanone upon oxidation with alkaline KMnO₄, as correctly identified in the answer.
12. In Clemmensen reduction, carbonyl compound is treated with…… .
(a) zinc amalgam
(b) sodium amalgam
(c) zinc amalgam + nitric acid
(d) sodium amalgam
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Answer
(a) Clemmensen reduction is used to convert carbonyl group to
Zinc amalgam and
Multiple Choice Questions (More Than One Options)
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(b) sodium amalgam
: Sodium amalgam is not used in Clemmensen reduction. The specific reagent required is zinc amalgam, which has different chemical properties and reactivity compared to sodium amalgam. -
(c) zinc amalgam + nitric acid: Nitric acid is an oxidizing agent and would not facilitate the reduction of a carbonyl group to a
group. Instead, it would likely oxidize the compound further. -
(d) sodium amalgam
: Similar to option (c), nitric acid is an oxidizing agent and would not be suitable for the reduction process. Additionally, sodium amalgam is not the correct reagent for Clemmensen reduction.
13. Which of the following compounds do not undergo aldol condensation?
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Answer
(b, d)
Necessary condition for aldol condensation is the presence of atleast one
- Compound (a) undergoes aldol condensation because it has at least one
-hydrogen atom. - Compound (c) undergoes aldol condensation because it has at least one
-hydrogen atom.
14. Treatment of compound
(a) phenol
(b) sodium phenoxide
(c) sodium benzoate
(d) benzophenone
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Answer
( b, c)
Treatment of compound
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Phenol: Phenol is not formed directly in this reaction because the nucleophilic substitution reaction with NaOH results in the formation of sodium phenoxide, not free phenol. Phenol would only be formed if the sodium phenoxide were subsequently acidified.
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Benzophenone: Benzophenone is not formed in this reaction because the reaction mechanism involves the cleavage of the ester bond, leading to the formation of sodium phenoxide and sodium benzoate. There is no pathway in this reaction that would result in the formation of benzophenone.
15. Which of the following conversions can be carried out by Clemmensen reduction?
(a) Benzaldehyde into benzyl alcohol
(b) Cyclohexanone into cyclohexane
(c) Benzoyl chloride into benzaldehyde
(d) Benzophenone into diphenyl methane
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Answer
Clemmensen reduction is used to convert cyclohexanone into cyclohexane and benzophenone into diphenyl methane as follows
Reagent used in Clemmensen reduction is zinc amalgam in hydrochloric acid, i.e.,
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(a) Benzaldehyde into benzyl alcohol: Clemmensen reduction is not suitable for reducing aldehydes to alcohols. It specifically reduces carbonyl groups (C=O) in ketones and aldehydes to methylene groups (CH2), but it does not convert aldehydes to alcohols.
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(c) Benzoyl chloride into benzaldehyde: Clemmensen reduction does not convert acyl chlorides (like benzoyl chloride) to aldehydes. It reduces carbonyl compounds to hydrocarbons, but it does not perform partial reductions to form aldehydes from acyl chlorides.
16. Through which of the following reactions number of carbon atoms can be increased in the chain?
(a) Grignard reaction
(b) Cannizzaro’s reaction
(c) Aldol condensation
(d) HVZ reaction
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Answer
(a, c)
Grignard reaction and aldol condensation is used to increase the number of carbon atom in the chain as follows
Grignard reaction
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Aldol condensation
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While other two reactions Cannizzaro reaction and HVZ reaction don’t lead to increase in number of carbon atom.
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Cannizzaro’s reaction: This reaction involves the disproportionation of non-enolizable aldehydes in the presence of a strong base, resulting in the formation of an alcohol and a carboxylic acid. It does not lead to an increase in the number of carbon atoms in the chain.
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HVZ reaction: The Hell-Volhard-Zelinsky (HVZ) reaction is used for the halogenation of carboxylic acids at the alpha position. This reaction does not increase the number of carbon atoms in the chain.
17. Benzophenone can be obtained by…… .
(a) benzoyl chloride + benzene
(b) benzoyl chloride + diphenyl cadmium
(c) benzoyl chloride + phenyl magnesium chloride
(d) benzene + carbon monoxide
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Answer
(
(a) Benzophenone can be obtained by Friedel-Craft acylation reaction. The reaction is shown as
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(b) Benzophenone can also be obtained by the reaction between benzoyl chloride and diphenyl cadmium.
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(c) benzoyl chloride + phenyl magnesium chloride: This reaction would produce a tertiary alcohol (triphenylmethanol) rather than benzophenone. The Grignard reagent (phenyl magnesium chloride) reacts with benzoyl chloride to form an intermediate which, upon hydrolysis, yields the tertiary alcohol.
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(d) benzene + carbon monoxide + ZnCl2: This reaction is known as the Gattermann-Koch reaction, which typically produces benzaldehyde, not benzophenone. The reaction involves the formylation of benzene to introduce a formyl group (-CHO) rather than a ketone group (C=O) bonded to two phenyl groups.
18. Which of the following is the correct representation for intermediate of nucleophilic addition reaction to the given carbonyl compound
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Answer
Since, carbonyl compound is a planar molecule hence two orientation of molecule regarding attack of nucleophile is possible as follows
Since, the product contains a chiral carbon, therefore, attack of nucleophile can occur either from front side attack or rear side attack giving enantiomeric products. Hence, (a) and (b) are the correct choices.
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Option (c) is incorrect because it does not represent the intermediate formed during the nucleophilic addition reaction. The intermediate should have a tetrahedral geometry around the carbonyl carbon, but option (c) does not show this structure.
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Option (d) is incorrect because it also does not represent the correct intermediate. The intermediate should have a negatively charged oxygen atom (alkoxide ion) and a tetrahedral carbon center, which is not depicted in option (d).
Short Answer Type Questions
19. Why is there a large difference in the boiling points of butanal and butan-1-ol?
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Thinking Process
This problem based upon the concept of
Answer
Butan-1-ol has intermolecular
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Butanol has polar
20. Write a test to differentiate between pentan-2-one and pentan-3-one.
Show Answer
Thinking Process
This problem is based on the concept of iodoform test. The organic compound containing
Answer
lodoform test (yellow ppt. formed when heated with sodium hypohalite) Pentan-2-one gives positive test as it contains -
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21. Give the IUPAC names of the following compounds.
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(c)
(d)
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Answer
Following are the IUPAC names of the compounds
(a)
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3-phenylprop-2-en-1-al
(b)
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Cyclohexanecarbaldehyde
(c)
3-oxo-pentan-1-al
(d)
But-2-en-1-al
22. Give the structure of the following compounds.
(a) 4-nitropropiophenone
(b) 2-hydroxycyclopentanecarbaldehyde
(c) Phenyl acetaldehyde
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Answer
(a) 4-nitropropiophenone
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(b) 2-hydroxycyclopentanecarbaldehyde
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(c) Phenyl acetaldehyde
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23. Write IUPAC names of the following structures
(a)
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Answer
The IUPAC names of the following structures are
(a)
Ethan-1, 2-dial
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Benzene-1, 4-y dicarbaldehyde
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24. Benzaldehyde can be obtained from benzal chloride. Write reactions for obtaining benzal chloride and then benzaldehyde from it.
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Answer
It is the commercial method for preparing benzaldehyde. Benzal chloride can be obtained by photochlorination of toluene i.e., chlorination of toluene in presence of sunlight. Then, benzal chloride on heating with boiling water produces benzaldehyde as shown below.
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25. Name the electrophile produced in the reaction of benzene with benzoyl chloride in the presence of anhydrous
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Answer
Benzene, on reaction with benzoyl chloride undergo formation of benzophenone through intermediate benzoylinium cation.
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This is an example of Friedel-Craft acylation reaction.
26. 0xidation of ketones involves carbon-carbon bond cleavage. Name the products formed on oxidation of 2, 5-dimethylhexan-3-one.
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Thinking Process
This problem is based on concept of cleavage of
Answer
According to Popoff’s rule, the unsymmetrical ketone on oxidation,
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27. Arrange the following in decreasing order of their acidic strength and give reason for your answer.
Show Answer
Thinking Process
This problem based on the concept of acidic strength, inductive effect and conjugation.
- Presence of + I group decreases acidic strength.
- Presence of - I group increases acidic strength.
Answer
Reasons
(i) More the electron withdrawing nature of substituent, more is the acidic strength.
(ii) Direct attachment of
(iii) Alcohols are weakly acidic than carboxylic acids.
28. What product will be formed on reaction of propanal with 2-methylpropanal in the presence of
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Thinking Process
This problem based on the concept of cross aldol condensation.
Answer
It is an example of cross aldol condensation.
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29. Compound ’
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Thinking Process
This problem includes conceptual mixing of preparation and properties of carboxylic acid and ester. Try to catch the key point of the process.
Answer
Since,
30. Arrange the following in decreasing order of their acidic strength. Give explanation for the arrangement.
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Answer
The decreasing order of their acidic strength
Acidic strength decreases as the number of electron withdrawing substituent(s) linked to
31. Alkenes
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Answer
Nature of chemical reaction occurring on
- Due to electronegativity difference between carbon and oxygen
Thus, in
32. Carboxylic acids contain carbonyl group but do not show the nucleophilic addition reaction like aldehydes or ketones. Why?
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Answer
Carboxylic acid contain carbonyl group but do not show nucleophilic addition reaction like aldehyde and ketone. Due to resonance as shown below the partial positive charge on carbonyl carbon atom is reduced.
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33. Identify the compounds
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Answer
Complete chemical conversion can be done as
Hence,
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34. Why are carboxylic acids more acidic than alcohols or phenols although all of them have hydrogen atom attached to a oxygen atom
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Answer
Carboxylic acids are more acidic than alcohol or phenol, although all of them have
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Hence, dissociation of
35. Complete the following reaction sequence.
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Answer
The complete chemical transformation can be shown as
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36. Ethyl benzene is generally prepared by acetylation of benzene followed by reduction and not by direct alkylation. Think of a possible reason.
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Answer
Preparation of ethyl benzene from acylation of benzene and reduction can be shown as
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The direct alkylation can not be performed because there is polysubstitution product is formed. Due to disadvantage of polysubstitution that Friedel-Craft’s alkylation reaction is not used for preparation of alkylbenzenes. Instead of Friedel-Craft’s acylation is used.
37. Can Gatterman-Koch reaction be considered similar to Friedel-Craft’s acylation? Discuss.
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Answer
In Gatterman-Koch reaction, benzene or its derivative is treated with
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While in Friedel-Craft acylation, acyl group is transferred to carbon of benzene and acyl benzene is obtained as a result.
This can be done by reaction of benzene with acyl chloride in the presence of anhydrous
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Formyl chloride is unstable in nature. So, it can be transferred by only Gattermann-Koch reaction not by Friedel-Craft reaction.
Matching The Columns
38. Match the common names given in Column I with the IUPAC names given in Column II.
Column I (Common names) |
Column II (IUPAC names) |
||
---|---|---|---|
A. | Cinnamaldehyde | 1. | Pentanal |
B. | Acetophenone | 2. | Prop-2-en-al |
C. | Valeraldehyde | 3. | 4-methylpent-3-en-2-one |
D. | Acrolein | 4. | 3-phenylprop-2-en-al |
E. | Mesityl oxide | 5. | 1-phenylethanone |
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Answer
A.
B.
C.
D.
E.
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39. Match the acids given in Column I with their correct IUPAC names given in Column II.
Column I (Acids) |
Column II (IUPAC names) |
|
---|---|---|
A. | Phthalic acid | 1. Hexane-1, 6-dioic acid |
B. | Oxalic acid | 2. Benzene-1, 2-dicarboxylic acid |
C. | Succinic acid | 3. Pentane-1, 5-dioic acid |
D. | Adipic acid | 4. Butane-1, 4-dioic acid |
E. | Glutaric acid | 5. Ethane-1, 2-dioic acid |
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Answer
A.
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40. Match the reactions given in Column I with the suitable reagents given in Column II.
Column I (Reactions) |
Column II (Reagents) |
||
---|---|---|---|
A. | Benzophenone Diphenylmethane |
1. | |
B. | Benzaldehyde 1 -phenylethanol |
2. | DIBAL-H |
C. | Cyclohexanone |
3. | |
D. | Phenyl benzoate Benzaldehyde |
4. |
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Answer
A.
B.
C.
D.
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41. Match the example given in Column I with the name of the reaction in Column II.
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Column I (Example) |
Column II (Reaction) |
||
---|---|---|---|
D. | 4. | Cannizzaro’s reaction |
|
E. | 5. | Rosenmund’s reduction |
|
F. | 6. | Stephen’s reaction |
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Answer
A.
B.
C.
D.
E.
F.
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Assertion and Reason
In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct answer out of the following choices.
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(e) Assertion and reason both are correct statements but reason is not correct explanation of assertion.
42. Assertion (A) Formaldehyde is a planar molecule. Reason (
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Answer
(a) Assertion and reason are correct and reason is the correct explanation of assertion. Formaldehyde is planar molecule due to
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43. Assertion (A) Compounds containing -
Reason (
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Answer
(e) Assertion and reason both are correct but reason is not the correct explanation of assertion.
Compounds containing -
44. Assertion (A) The
Reason (R) The anion formed after the loss of
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Answer
(d) Assertion is wrong statement but reason is correct statement.
Correct assertion is the
45. Assertion (A) Aromatic aldehydes and formaldehyde undergo Cannizzaro reaction.
Reason (R) Aromatic aldehydes are almost as reactive as formaldehyde.
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Answer
(c) Assertion is the correct statement but reason is the wrong statement.
Aromatic aldehyde and formaldehyde undergo Cannizzaro reaction due to absence of
46. Assertion (A) Aldehydes and ketones, both react with Tollen’s reagent to form silver mirror.
Reason ( R ) Both, aldehydes and ketones contain a carbonyl group.
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Answer
(d) Assertion is wrong statement but reason is the correct statement.
Aldehydes but not ketones react with Tollen’s reagent to form silver mirror. Reason is correct statement as aldehyde and ketone both contain carbonyl group.
Long Answer Type Questions
47. An alkene ’
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Thinking Process
This problem is based on conceptual mixing of preparation and properties of carbonyl compound including ozonolysis, iodoform test.
Only aldehyde (not ketone) undergo Fehling test.
Compound containing
Draw all possible structures of A using degree of unsaturation calculations then choose the correct structure using information provided above in the question.
Answer
Molecular formula
Degree of unsaturation
where,
Compound
Possible structures of alkene are
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Ozonolysis of structure I produces aldehyde only
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Ozonolysis of structure II produces aldehyde only
Ozonolysis of structure III produces aldehyde only
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Ozonolysis of structure IV produces both aldehyde and ketone
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After ozonolysis of each of structures I, II and III produces only aldehydes as both components. But as given in the question one compound doesn’t give Fehling test but must give iodoform test. Hence, compound must be a ketone with
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Formation of iodoform from ’
48. An aromatic compound ’
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Thinking Process
This problem is based on conceptual mixing of 2, 4-DNP test, iodoform test and oxidation reactions. Search the key point by using by which this question can be answered easily. Follow the following stepwise approach to solve this question.
- Determine all possible structures of molecule using degree of unsaturation.
- Use the concept of chemical test given by aldehyde and ketone to identify the correct structure.
- After choosing any predicted structure complete the sequence of reaction.
Answer
Molecular formula
Degree of unsaturation
Degree of unsaturation
Thus, possible structures are
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According to question, compound ’
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49. Write down functional isomers of a carbonyl compound with molecular formula
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Answer
Functional isomers of
(a) Propanal,
(b) The reaction mechanism is as follow
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The reaction does not lead to completion because it is a reversible reaction. Equilibrium is established.
(c) If a strong acid is added to the reaction mixture, the reaction is inhibited because production of
50. When liquid ’
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Answer
Since the liquid
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Note Aldehyde and ketone both gives white crystallie solid with sodium hydrogen sulphite but this is only aldehyde which gives Tollen’s test and Fehling’s test.