4C - Haloalkanes
- Created by: Strelly22
- Created on: 29-03-21 11:54
View mindmap
- 4C - Haloalkanes
- Definitions
- Electronegativity
- the measure of the attraction of a bonded atom for the shared pair of electrons in a covalent bond
- Hydrolysis
- a chemical reaction involving water or an aqueous solution of an hydroxide that causes the breaking of a bond in a molecule
- Reflux
- the continual boiling and condensing of a reaction mixture back to original container to ensure that the reaction takes place without the contents of the flask boiling dry
- Nucleophile
- an electron pair donor
- Electronegativity
- Introduction to haloalkanes
- to classify a haloalkane, consider the carbocation that would be formed if the halogen atom was left as a halide ion
- primary = 2Hs
- secondary = 1H
- tertiary = 0Hs
- Boiling Points
- alcohol > 1-chloroalkanes > alkanes
- 2-chloropropane < 1-chloropropane as smaller contact area ? LF weaker ? less energy
- to classify a haloalkane, consider the carbocation that would be formed if the halogen atom was left as a halide ion
- Reactivity of haloalkanes
- haloalkanes > alkanes
- C-X weaker than C-H so breaks more easily, allowing haloalkanes to react
- except C-F
- C-X weaker than C-H so breaks more easily, allowing haloalkanes to react
- preparation of a alcohol by hydrolysis of a haloalkane
- reagent: aqueous NaOH
- conditions: heat under reflux
- organic reactions require heating under reflux as they have simple molecular structures ? relatively low bp compared to ionic compounds such as salts
- haloalkanes > alkanes
- Rate of hydrolysis of haloalkanes
- iodo > bromo > chloro
- hot water speeds up the reaction
- AgNO3 (aq): provides the water + traps the halide ion by forming a precipitate
- ethanol was used as a co solvent
- rate of reaction was compared by by timing how long it took for a visible quantity of silver halide precipitate
- Uses of haloalkanes
- tetrafluoroethene
- TFE
- 'Teflon', non stick cookware
- dichlorodifluoromethane
- Freon-12
- refrigerant, aerosol spray propllent (silly string)
- trichloroethene
- TCE
- solvent, anaesthetic
- trichloromethane
- chloroform
- (anaesthetic), precursor to other organic products
- 2-bromo-2-chloro-1,1,1-trifluoromethane
- Halothane
- general anaesthetic
- bromotrifluoromethane
- Halon 1301
- fire extinguishers
- poly-chloroethene
- PVC
- plastic pipes, electrical cable insulation, waterproof clothing
- poly(tetra-fluoroethene)
- Teflon
- coating on non-stick cookware
- chlorodifluoromethane
- HCFC-22
- propellant and refrigerant
- 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane
- DDT
- insecticide
- tetrafluoroethene
- CFC's and the Ozone Layer
- Ozone
- outer edge of stratosphere
- ozone formed
- 1) O2 + uv ? 2O.
- 2) O2 + O. ? O3
- ozone broken down
- O3 + uv ? O2 + O.
- photodissociation of CFCs causes chlorine radicals (initiation)
- CF2Cl2. ?CF2Cl. + Cl.
- homolytic fission
- uv light required
- O3 + O ? 2O2 overall
- Cl is a catalyst
- NO breaks down ozone (propagation)
- from lightening strikes and high flying aircraft
- O3 + O ? 2O2 overall
- homogenous as catalysts and reactants in the same phase
- CFCs
- chlorofluorocarbon
- hydrochlorofluorocarbon
- refrigerants + aerosol spray propellants
- Ozone
- Definitions
Comments
No comments have yet been made