Haloalkanes Nucleophilic Substitution Reactions

Study Notes

Haloalkanes

Nucleophilic Substitution

Haloalkanes undergo nucleophilic substitution reactions, where a nucleophile (a species with an electron pair) replaces the halogen atom.
Types of nucleophilic substitution reactions:
1. S_N_1 (Unimolecular Nucleophilic Substitution):
  - Rate-determining step: Formation of a carbocation intermediate.
  - Fast step: Nucleophile attacks the carbocation.
  - Stereospecific: Racemic mixture formed.
2. S_N_2 (Bimolecular Nucleophilic Substitution):
  - Concerted mechanism: Nucleophile attacks the carbon atom simultaneously with the departure of the leaving group.
  - Stereospecific: Inversion of stereochemistry.

Chemical Reactions

Haloalkanes can undergo various chemical reactions, including:
- Hydrolysis: Reaction with water to form an alcohol.
- Alkaline hydrolysis: Reaction with hydroxide ions to form an alcohol.
- Grignard reaction: Reaction with Grignard reagents to form a carbon-carbon bond.

Haloarenes

Electrophilic Aromatic Substitution

Haloarenes undergo electrophilic aromatic substitution reactions, where an electrophile (a species that accepts an electron pair) replaces the halogen atom.
Types of electrophilic aromatic substitution reactions:
- Halogenation: Replacement of a halogen atom with another halogen atom.
- Nitration: Replacement of a halogen atom with a nitro group (-NO2).
- Sulfonation: Replacement of a halogen atom with a sulfo group (-SO3H).
Mechanism:
1. Formation of an electrophile (e.g., bromine or chlorine molecule).
2. Electrophile attacks the aromatic ring, forming a carbocation intermediate.
3. Loss of a proton to form the product.

Chemical Reactions

Haloarenes can undergo various chemical reactions, including:
- Nucleophilic aromatic substitution: Reaction with a nucleophile to replace the halogen atom.
- Reductive dehalogenation: Reaction with a reducing agent to remove the halogen atom.

Haloalkanes

Nucleophilic Substitution

Haloalkanes undergo nucleophilic substitution reactions, where a nucleophile replaces the halogen atom.
There are two types of nucleophilic substitution reactions:

S_N_1 (Unimolecular Nucleophilic Substitution)

Rate-determining step is the formation of a carbocation intermediate.
Fast step is the nucleophile attacking the carbocation.
Reaction is stereospecific, resulting in a racemic mixture.

S_N_2 (Bimolecular Nucleophilic Substitution)

Reaction occurs through a concerted mechanism, where the nucleophile attacks the carbon atom simultaneously with the departure of the leaving group.
Reaction is stereospecific, resulting in an inversion of stereochemistry.

Chemical Reactions

Haloalkanes can undergo various chemical reactions, including:
Hydrolysis: reaction with water to form an alcohol.
Alkaline hydrolysis: reaction with hydroxide ions to form an alcohol.
Grignard reaction: reaction with Grignard reagents to form a carbon-carbon bond.

Haloarenes

Electrophilic Aromatic Substitution

Haloarenes undergo electrophilic aromatic substitution reactions, where an electrophile replaces the halogen atom.
There are three types of electrophilic aromatic substitution reactions:
Halogenation: replacement of a halogen atom with another halogen atom.
Nitration: replacement of a halogen atom with a nitro group (-NO2).
Sulfonation: replacement of a halogen atom with a sulfo group (-SO3H).
The mechanism involves:
Formation of an electrophile (e.g., bromine or chlorine molecule).
Electrophile attacking the aromatic ring, forming a carbocation intermediate.
Loss of a proton to form the product.

Chemical Reactions

Haloarenes can undergo various chemical reactions, including:
Nucleophilic aromatic substitution: reaction with a nucleophile to replace the halogen atom.
Reductive dehalogenation: reaction with a reducing agent to remove the halogen atom.

Description

Learn about nucleophilic substitution reactions in haloalkanes, including SN1 and SN2 reactions, rate-determining steps, and stereochemistry. Test your understanding of this important organic chemistry topic!