Alkenes Flashcards
Unsaturated molecules
- C=C
- contains one or more double bonds
Alkene vs alkane boiling point
- less surface contact than alkanes
- less induced dipole-dipole forces
- lower boiling point
Sigma bond
- single covalent bond
- shared pair of electrons
- electron density concentrated between two nuclei
Pi bond
- sideways overlap of two p-orbitals
- between adjacent carbon atoms
- provides one electron each
- weaker than sigma
C=C bond
- trigonal planar
- 120 degrees
- three paired electrons
Sterioisomerism
- same molecular and structural formula
- different 3D spatial arrangement
Reasons for sterioisomerism
- restricted rotation of C=C double bond
- different 3D arrangement of R groups
Solubility
insoluble in water
CIP rules E isomer
- two attached atoms with highest atomic number
- diagonally opposite side of double bond
CIP rules Z isomer
- two attached atoms with highest atomic number
- not diagonally opposite side of double bond
Alkene to alkane
Reagent: hydrogen
Conditions: nickel, heat
Mechanism: hydrogenation/ addition
Alkene test
Reagent: orange bromine water
Observations: decolourisation
Alkene to haloalkane
Reagent: hydrogen halide / halogen
Mechanism: electrophilic addition
Alkene to alcohol
Reagent: steam
Conditions: H3PO4, heat, high pressure
Mechanism: hydration
Electrophile
- electron pair acceptor
- attracted to electron dense regions
Heterolytic fission
- molecule moves to alkene
- induced dipole
- heterolytic fission
- become electrophile
Markownikoff’s rule
- addent goes to least hydrogenated C
- other than hydrogen
- forms more stable carbocation
Polymer properties
1.non-biodegradable
2. resistant to chemical attack
3. not broken down by bacteria
Benefits of processing waste polymers
- combustion for energy production
- organic feedstock for production of new polymers
- cracking
Benefits of biodegradable
- has active functional group that can be attacked by bacteria
- sustainable and doesn’t use finite resources
Incineration
- toxic fumes produced
- use gas scrubbers
- produces energy
- saves landfill sites
Feedstock
waste can produces other organic compounds
Recycling disadvanatge
- high collection cost
- lots of different polymers must be separated