Halogenoalkanes - 2
- Created by: Shannon
- Created on: 09-05-14 14:25
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- Halogenoalkanes
- Hydrocarbon chain attached to a halogen atom
- Classification
- Primary
- Carbon attached to halogen is also attached to one other carbon
- Secondary
- Carbon attached to halogen is also attached to 2 other carbons
- Tertiary
- Carbon attached to halogen is also attached to 3 other carbons
- Primary
- Reactivity
- Tertiary halogenoalkanes are the most reactive
- Shorter bonds are stronger, and so do not break as easily
- Tested using water and silver nitrate solution
- Formation of a ppt
- Tertiary halogenoalkanes are the most reactive
- Preparation of halogenoalkane from an alcohol
- Reacted with a metal halide and conc H2SO4 to produce a hydrogen halide
- Hydrogen halide reacts with the corresponding alcohol to make a halogenoalkane
- This method is not used to make a bromoalkane or an iodoalkane
- The sulfuric acid will oxidise the iodide ions to iodine and reduce to hydrogen sulfide
- The sulfuric acid will oxidise the bromide ions to bromine and reduce to sulfur dioxide
- End up with by-products and a reduced yield of halogenoalkane
- Reacted with a metal halide and conc H2SO4 to produce a hydrogen halide
- Uses
- Produce polymers
- E.g chloroethane, which makes PVC
- Refrigerants
- Fire retardants
- Due to being non-flammable
- Produce polymers
- Chlorofluorocarbons have caused ozone depletion
- Reactions with...
- Aqueous alkali to form alcohols
- Warm aqueous NaOH or KOH under refux
- Nucleophilic substitution reaction
- Alcoholic KOH
- Elimination reaction occurs
- Heated under reflux in ethanol
- The halogen atom is eliminated along with a hydrogen from a neighbouring carbon atom
- A double bond is formed between the two carbon atoms
- Alcoholic ammonia
- Warmed under reflux with an excess of ethanolic ammonia
- Occurs in 2 stages
- Stage 1
- Salt formed
- Nucleophilic substitution
- Stage 2
- Ammonia molecule removes a H from NH3 group, forming an ammonium ion
- Ammonium ion reacts with the bromine ion to form ammonium bromide
- Ammonia molecule removes a H from NH3 group, forming an ammonium ion
- Stage 1
- Aqueous alkali to form alcohols
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