Chemistry Class 11 NCERT Solutions: Chapter 12 Organic Chemistry Some Basic Principles and Techniques Part 7 (For CBSE, ICSE, IAS, NET, NRA 2023)

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Q: 12. What are electrophiles and nucleophiles? Explain with examples.

Answer

An electrophile is a reagent that takes away an electron pair. In other words, an electron-seeking reagent is called an electrophile . Electrophiles are electron3 deficient and can receive an electron pair.

Carbocations and neutral molecules having functional groups such as carbonyl group

Q_12_Structure of Carbonyl Group of Electrophiles

are examples of electrophiles. A nucleophile is a reagent that brings an electron pair. In other words, a nucleus3seeking reagent is called a nucleophile (Nu:) .

For example: , carbanions etc.

Neutral molecules such as and ammonia also act as nucleophiles because of the presence of a lone pair.

Q: 13. Identify the reagents shown in bold in the following equations as nucleophiles or electrophiles:

(A)

(B)

(C)

Answer:

Electrophiles are electron-deficient species and can receive an electron pair. On the other hand, nucleophiles are electron3rich species and can donate their electrons.

(A)

Here, acts as a nucleophile as it is an electron-rich species, i.e.. , it is a nucleus-seeking species.

(B)

Here, acts as a nucleophile as it is an electron – rich species, i.e.. , it is a nucleus- seeking species.

(C)

Here, acts as an electrophile as it is an electron – deficient species.

Q: 14. Classify the following reactions in one of the reaction type studied in this unit.

(A)

(B)

(C)

(D)

Answer:

(A) It is an example of substitution reaction as in this reaction the bromine group in bromoethane is substituted by the – SH group.

(B) It is an example of addition reaction as in this reaction two-reactant molecules combine to form a single product.

(C) It is an example of elimination reaction as in this reaction hydrogen and bromine are removed from bromoethane to give Ethene.

(D) In this reaction, substitution takes place, followed by a rearrangement of atoms and groups of atoms.