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Question 1

Neutral Nucleophiles in Substitution:

Answer 1

Neutral nucleophiles, such as
H2O, NH3, and (CH3)3N, can participate in substitution reactions.
The substitution product initially bears a positive charge due to the nucleophile’s lone pair forming a bond with the electrophilic carbon.

Question 2

Charge in the Product:

Answer 2

The positive charge arises because the nucleophile is neutral and donates a pair of electrons while retaining all its atoms/groups.
Example:
(CH3)3N results in
(CH3)3N+ in the product.

Question 3

Proton Loss to Neutralize:

Answer 3

If the positive charge is caused by a proton (H) on oxygen or nitrogen, the product can lose the proton in an acid-base reaction to form a neutral compound.
This often happens when the nucleophile is water (H2O) or an amine (NH3).

Question 4

Reaction Example

CH3CH2CH2Br +(CH3)3N→CH3CH2CH2N(CH3)3+ +Br−

Answer 4

Substrate:
CH3CH2CH2Br (1-bromopropane).
Nucleophile:
(CH3)3N(trimethylamine).
Product:
CH3CH2CH2N(CH3)3+(a quaternary ammonium salt).
Leaving Group:
Br−.

Question 5

Question: What happens to the product when a neutral nucleophile is used?

Answer 5

Answer: The product initially bears a positive charge.

Question 6

Question: Why does the substitution product have a positive charge?

Answer 6

Answer: The nucleophile donates an electron pair to form a bond but retains all its atoms/groups, leading to a positive charge.

Question 7

Question: How can a positively charged product become neutral?

Answer 7

Answer: By losing a proton in a Brønsted-Lowry acid-base reaction.

Question 8

What is the product when
CH3CH2CH2Br reacts with ?

Answer 8

Answer:
CH3CH2CH2NH3+
, which can lose a proton to form
CH3CH2CH2NH2(1-propylamine).

Question 9

Question: What is the role of
(CH3)3N in substitution reactions?

Answer 9

Answer:
(CH3)3N acts as a neutral nucleophile, forming a quaternary ammonium salt.