Nomenclature and Reactivity of Haloalkanes

Haloalkanes: Organic compounds containing carbon, hydrogen, and halogen (F, Cl, Br, I).
Common names: Based on alkane parent structure, naming halogen as a prefix (e.g., methyl chloride for CH3Cl).
IUPAC naming:
- Identify longest carbon chain.
- Number carbon chain to give the halogen the lowest number.
- Name halogen as a substituent (bromo-, chloro-, iodo-, or fluoro-).
- Example: 2-bromopentane (Br on the second carbon of a five-carbon chain).

Haloarenes: Aromatic compounds where one or more hydrogen atoms are replaced by halogens.
Key factors influencing reactivity:
- Resonance: Halogen atoms stabilize the aromatic system, making haloarenes less reactive than haloalkanes.
- Electrophilicity: Halogen atoms are weakly deactivating; they withdraw electrons but can still participate in electrophilic aromatic substitution.
Substitution reactions: Commonly proceed via electrophilic aromatic substitution rather than nucleophilic substitution.

From alkanes:
- Halogenation (free radical substitution) using Cl2 or Br2, typically in ultraviolet (UV) light.
From alkenes:
- Electrophilic addition of HX (HX = HCl, HBr, HI) to alkenes.
From alcohols:
- Converting alcohols to haloalkanes using PCl3, SOCl2, or reagents like PBr3.
From arenes:
- Nucleophilic aromatic substitution with strong nucleophiles (e.g., NaI) or via direct halogenation with halogens in the presence of a catalyst (e.g., FeBr3).

Haloalkanes:
- SN1 Mechanism:
  - Two-step process: formation of carbocation followed by nucleophile attack.
  - Favored in tertiary haloalkanes.
- SN2 Mechanism:
  - One-step process: nucleophile attacks the electrophilic carbon while the leaving group departs.
  - Favored in primary haloalkanes; results in inverted stereochemistry.
Haloarenes:
- Electrophilic Aromatic Substitution:
  - The aromatic ring acts as a nucleophile, attacking an electrophile.
  - Halogen acts as a deactivating group, influencing the rate and position of substitution.
- Nucleophilic Aromatic Substitution:
  - Occurs under specific conditions, often involving an electron-withdrawing group (e.g., nitro group) ortho or para to the halogen.
  - Mechanism includes a Meisenheimer complex intermediate.

Haloalkanes are organic compounds containing carbon, hydrogen, and a halogen (F, Cl, Br, I).
Common names are based on the parent alkane structure with the halogen named as a prefix (e.g., methyl chloride for CH3Cl).
IUPAC naming involves:
- Identifying the longest carbon chain.
- Numbering the chain to assign the halogen the lowest possible number.
- Naming the halogen as a substituent using prefixes like "bromo-", "chloro-", "iodo-", or "fluoro-".
- Example: 2-bromopentane (Br on the second carbon of a five-carbon chain).

Haloarenes are aromatic compounds where one or more hydrogen atoms are replaced by halogens.
Factors influencing reactivity:
- Resonance: Halogen atoms stabilize the aromatic system, making haloarenes less reactive than haloalkanes.
- Electrophilicity: Halogen atoms are weakly deactivating; they withdraw electrons but can still participate in electrophilic aromatic substitution.
Substitution reactions: Haloarenes typically undergo electrophilic aromatic substitution rather than nucleophilic substitution.

From alkanes: Halogenation (free radical substitution) using Cl2 or Br2, typically in ultraviolet (UV) light.
From alkenes: Electrophilic addition of HX (HX = HCl, HBr, HI) to alkenes.
From alcohols: Converting alcohols to haloalkanes using PCl3, SOCl2, or reagents like PBr3.
From arenes: Nucleophilic aromatic substitution with strong nucleophiles (e.g., NaI) or via direct halogenation with halogens in the presence of a catalyst (e.g., FeBr3).

Haloalkanes:
- SN1 Mechanism: Two-step process; formation of carbocation followed by nucleophile attack. Favored in tertiary haloalkanes.
- SN2 Mechanism: One-step process; nucleophile attacks the electrophilic carbon while the leaving group departs. Favored in primary haloalkanes, results in inverted stereochemistry.
Haloarenes:
- Electrophilic Aromatic Substitution: Aromatic ring acts as a nucleophile, attacking an electrophile. Halogen acts as a deactivating group, influencing the rate and position of substitution.
- Nucleophilic Aromatic Substitution: Occurs under specific conditions, often involving an electron-withdrawing group (e.g., nitro group) ortho or para to the halogen. Involves a Meisenheimer complex intermediate.