Organic Chemistry Questions and Answers – Condensation Reactions

This set of Organic Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Condensation Reactions”.

1. Condensation reaction is the reverse of which of the following reaction?
a) lock and key hypothesis
b) oxidation
c) hydrolysis
d) glycogen formation
View Answer

Answer: c
Explanation: This reaction example is the reverse of hydrolysis, which splits a chemical entity into two parts through action from the polar water molecule, which itself splits into hydroxide and hydrogen ions.

2. Condensation reaction always results in the formation of complex sugar (disaccharide or polysaccharide) and which of the following?
a) amino acids
b) lipids
c) water
d) maltose
View Answer

Answer: c
Explanation: Condensation reaction always results in the formation of complex sugar (disaccharide or polysaccharide) and water.

3. In which condensation an enol or an enolate ion reacts with a carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), followed by dehydration to give a conjugated enone happens?
a) Aldol condensation
b) Claisen reduction
c) Henry condensation
d) Knoevenagel condensation
View Answer

Answer: a
Explanation: Aldol condensation in which condensation an enol or an enolate ion reacts with a carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), followed by dehydration to give a conjugated enone happens.
advertisement
advertisement

4. Which combination of carbonyl compounds gives phenyl vinyl ketone by an aldol condensation?
Find combination of carbonyl compounds gives phenyl vinyl ketone by an aldol condensation
a) Acetophenone and ketone
b) Acetophenone and aldehyde
c) Benzaldehyde and aldehyde
d) Benzaldehyde and ketone
View Answer

Answer: a
Explanation: Draw the structures of the possible aldol products (3-hydroxy carbonyl compounds) before dehydration from the pairs of reactants shown below, then identify which aldol will lead to phenyl vinyl ketone upon dehydration.

5. Which ester will not give a good yield of the Claisen condensation product with NaOEt in EtOH?
a) Ester will not give good yield of the Claisen condensation product with NaOEt - option a
b) Ester will not give good yield of the Claisen condensation product with NaOEt - option b
c) Ester will not give good yield of the Claisen condensation product with NaOEt - option c
d) Ester will not give good yield of the Claisen condensation product with NaOEt - option d
View Answer

Answer: c
Explanation: The Claisen condensation is reversible and it is formation of a stabilized enolate of the product which leads to a high yield at equilibrium. When the product cannot give a stabilized enolate, the yield will be poor.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. What will be the product for the following reaction?
The product for the following reaction is trans-2,4-pentadienoic acid
a) trans-2,4-pentadienoic acid
b) cis -2,4-pentadienoic acid
c) 3-aminobenzoic acid
d) 2-aminobenzoic acid
View Answer

Answer: a
Explanation: With malonic compounds the reaction product can lose a molecule of carbon dioxide in a subsequent step. In the so-called Doebner modification the base is pyridine. For example, the reaction product of acrolein and malonic acid in pyridine is trans-2,4-Pentadienoic acid with one carboxylic acid group and not two.

7. What will be the product of the following reaction?
The product of the following reaction is –Nitro alcohol
a) –Nitro alcohol
b) -nitro alcohol
c) Nitroalkene
d) -amino alcohol
View Answer

Answer: a
Explanation: This is a Henry Reaction, it is the combination of a nitroalkane and an aldehyde or ketone in the presence of a base to form β-Nitro alcohols.
advertisement

8. What will be the product ‘B’ in the reaction?
The product ‘B’ in the reaction is α-nitro ketone
a) α-nitro alcohol
b) α-nitro ketone
c) nitroalkene
d) β-amino alcohol
View Answer

Answer: b
Explanation: This is a Henry Reaction, it is the combination of a nitroalkane and an aldehyde or ketone in the presence of a base to form β-Nitro alcohols, followed by oxidation of the secondary alcohol to yield α-nitro ketones.

9. What will be the product ‘B’ in the reaction?
The product ‘B’ in the reaction is nitroalkene
a) α-nitro alcohol
b) α-nitro ketone
c) nitroalkene
d) β-amino alcohol
View Answer

Answer: c
Explanation: This is a Henry Reaction, it is the combination of a nitroalkane and an aldehyde or ketone in the presence of a base to form β-Nitro alcohols, followed by dehydration of nitroalkene.
advertisement

10. What will be the product ‘B’ in the reaction?
The product ‘B’ in the reaction is β-amino alcohol
a) α-nitro alcohol
b) α-nitro ketone
c) nitroalkene
d) β-amino alcohol
View Answer

Answer: d
Explanation: This is a Henry Reaction, it is the combination of a nitroalkane and an aldehyde or ketone in the presence of a base to form β-Nitro alcohols, followed by reduction of the nitro group to yield β-amino alcohols.

Sanfoundry Global Education & Learning Series – Organic Chemistry.

To practice all areas of Organic Chemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.

advertisement
advertisement
Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & discussions at Telegram SanfoundryClasses.