Define electrophile .

An electrophile is an electron-deficient species that acts as an electron pair acceptor, attracted to regions of high electron density.

What is an electrophilic substitution reaction?

An electrophilic substitution reaction is one in which an atom or group of atoms in a molecule is replaced by an electron pair acceptor after an initial attack by that electron-deficient species.

True or False? Benzene undergoes addition reactions rather than substitution reactions when reacting with bromine.

False. Benzene undergoes substitution reactions (electrophilic substitution), not addition reactions. The aromatic stability of the benzene ring is maintained by substitution rather than addition.

Define nucleophilic addition-elimination .

A nucleophilic addition-elimination is a reaction type in which a nucleophile adds across a C=O bond (addition), followed by the loss of a small molecule such as HCl (elimination).

The hydrolysis of an acyl chloride is a nucleophilic addition-elimination reaction producing a .......... and .......... as products.

The hydrolysis of an acyl chloride is a nucleophilic addition-elimination reaction producing a carboxylic acid and HCl as products.

Give three examples of nucleophilic addition-elimination reactions of acyl chlorides.

Hydrolysis with water to form a carboxylic acid and HCl. Reaction with an alcohol to form an ester and HCl. Reaction with ammonia or a primary amine to form an amide and HCl.

True or False? In the esterification of an acyl chloride with an alcohol, the alcohol adds across the C–Cl bond.

False. The alcohol adds across the C=O bond (the carbonyl). The HCl molecule is then eliminated in the second step.

When propanoyl chloride reacts with a primary amine, the nitrogen's .......... attacks the carbonyl carbon, forming an amide after elimination of .......... .

When propanoyl chloride reacts with a primary amine, the nitrogen's lone pair attacks the carbonyl carbon, forming an amide after elimination of HCl .

Why does benzene undergo electrophilic substitution rather than addition when reacting with bromine?

Benzene's delocalised π electron ring system is highly stable ( aromaticity ). Substitution preserves this aromaticity by replacing H with Br. Addition would disrupt the delocalised ring and is energetically unfavourable.

A LevelChemistryCambridge (CIE)Flashcards29. An Introduction to A Level Organic ChemistryCharacteristic Organic Reactions

Characteristic Organic Reactions (Cambridge (CIE) A Level Chemistry): Flashcards

Exam code: 9701

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Define electrophile.

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Cards in this collection (9)

Define electrophile.
An electrophile is an electron-deficient species that acts as an electron pair acceptor, attracted to regions of high electron density.
What is an electrophilic substitution reaction?
An electrophilic substitution reaction is one in which an atom or group of atoms in a molecule is replaced by an electron pair acceptor after an initial attack by that electron-deficient species.
True or False?
Benzene undergoes addition reactions rather than substitution reactions when reacting with bromine.
False.
Benzene undergoes substitution reactions (electrophilic substitution), not addition reactions. The aromatic stability of the benzene ring is maintained by substitution rather than addition.
Define nucleophilic addition-elimination.
A nucleophilic addition-elimination is a reaction type in which a nucleophile adds across a C=O bond (addition), followed by the loss of a small molecule such as HCl (elimination).
The hydrolysis of an acyl chloride is a nucleophilic addition-elimination reaction producing a .......... and .......... as products.
The hydrolysis of an acyl chloride is a nucleophilic addition-elimination reaction producing a carboxylic acid and HCl as products.
Give three examples of nucleophilic addition-elimination reactions of acyl chlorides.
1. Hydrolysis with water to form a carboxylic acid and HCl.
2. Reaction with an alcohol to form an ester and HCl.
3. Reaction with ammonia or a primary amine to form an amide and HCl.
True or False?
In the esterification of an acyl chloride with an alcohol, the alcohol adds across the C–Cl bond.
False.
The alcohol adds across the C=O bond (the carbonyl). The HCl molecule is then eliminated in the second step.
When propanoyl chloride reacts with a primary amine, the nitrogen's .......... attacks the carbonyl carbon, forming an amide after elimination of .......... .
When propanoyl chloride reacts with a primary amine, the nitrogen's lone pair attacks the carbonyl carbon, forming an amide after elimination of HCl.
Why does benzene undergo electrophilic substitution rather than addition when reacting with bromine?
Benzene's delocalised π electron ring system is highly stable (aromaticity). Substitution preserves this aromaticity by replacing H with Br. Addition would disrupt the delocalised ring and is energetically unfavourable.

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