Haloalkanes possess a rich array of chemical properties, primarily involving substitution and elimination reactions. They can also undergo reduction and reactions with metals.
Specifically:
Core Chemical Reactions
Substitution Reaction (Hydrolysis)
This is the most basic reaction of haloalkanes, and all haloalkanes can undergo this reaction.
Reaction Conditions: NaOH aqueous solution, heating
Bond Breaking Nature: Breaking the C-X bond, the halogen atom (X) is replaced by a hydroxyl group (-OH).
Reaction Equation:
R−X + NaOH →
△ Water
R−OH + NaX
R−X+NaOH
Water
△
R−OH+NaX (R represents a hydrocarbon group)
Other Types: Besides hydrolysis, haloalkanes can also undergo alkoxy substitution to form ethers, cyano substitution to lengthen the carbon chain, ammonolysis to form amines, and reaction with silver nitrate alcohol solution to form silver halide precipitates. This result can be used to identify the types of haloalkanes.
Elimination Reaction (or Elimination of Hydrocarbons) Under specific conditions, a small molecule is eliminated to form an unsaturated hydrocarbon. Structural requirements apply.
Reaction Conditions: NaOH alcohol solution, heating
Structural Requirements: The carbon atom adjacent to the carbon atom bonded to the halogen atom must have a hydrogen atom. For example, CH₃Cl and (CH₃)₃CCH₂Cl cannot undergo elimination reactions.
Bond breaking essence: Simultaneous breaking of C-X bonds and adjacent C-H bonds, removing the HX small molecule.
Reaction equation:
RCH₂CH₂X + NaOH →
△ Alcohol
RCH=CH₂ + NaX + H₂O
RCH₂CH₂X + NaOH
Alcohol
△ RCH=CH₂ + NaX + H₂O
Product description: If adjacent carbons in the molecule are all attached to halogen atoms, a diene or carbon-carbon triple bond can be formed, following Zaitsev's rule.