2.5 Hydrocarbons Flashcards
Drawback Of Combustion
CO2 Production is a drawback of fossil fuel combustion, as are the formation of C and CO from incomplete combustion. SO2 and NOx are also produced from combustion of impurities in the fuels.
Photochlorination of alkanes
Reagent: Cl2
Conditions: UV light
Photochloration of Methane
Initiation:
Cl2 -> Cl. + Cl.
Propagation:
CH4 + Cl. -> CH3. + HCl
CH3. + Cl2 -> CH3Cl + Cl.
CH3Cl + Cl. -> CH2Cl. + HCl
CH2Cl. + Cl2 -> CH2Cl2 + Cl.
Termination:
Cl. + Cl. -> Cl2
Cl. + CH3. -> CH3Cl
CH3. + CH3. -> C2H6
E and Z isomers
For E isomers atoms of high priority are on either side of the carbons
For Z isomerism atoms of high priority must been on the same side.
Cis - same group on same side
Trands - same group on opposite sides
Alkane - bonds
Overlap of two s-orbitals, s and p orbital or two p-orbital form sigma bonds
Alkanes contain C-C and C-H which all of these single bonds are sigma bonds. Unreactive aside from combustion and free radical
Alkenes - bonds
Alkenes contain C-C, C-H and C=C. The double bonds consists of a sigma and pi bond (horizontal p orbitals make sigma bond and vertical p orbitals make pi bond)
Alkenes have a region of high electron density causing their reactive nature.
Double Bond
Double bond in alkene creates a region of high electron density and makes alkenes susceptible to electrophilic attack.
The double is weaker than two single bonds therefore it breaks quite easily to forma single bond, this makes them very reactive.
Hydrogenation
Reagent: H2
Conditions: Heat
Catalyst: Nickel metal
C4H8 + H2 -> C4H10
Polymerisation
- High heat and pressure required and an oxygen indicator
Ethene -> polyethene
Uses:
LDPE - shopping bags
HDPE - shampoo bottles,recycling bins
Propene -> polypropene
Uses:
Food containers
General kitchen equipment
Chloroethene -> polychloroethene (PVC)
Uses:
Water pipes
Waterproof clothing
Phenylethene -> polyphenylethene
Hard household plastic
Expanded polystyrene (air blown packaging)
