Alkenes Flashcards
What are alkenes
Unsaturated hydrocarbons with a double chain
Why can’t the alkenes double bond can’t rotate
As they contain a pi bond as they have overlapping orbitals
What types of isomers can alkenes form
Positional
Geometrical
What are postional isomers
This is when alkenes double bonds are in another position
What is geometrical isomerism
When the bonds are arranged differently around the c=c double bond
Z isomerism- same side
E isomerism -either side
What type of reactions do alkenes undergo
Electrophilic addition
What are electrophiles
They are electron deficient atoms that attack double bonds
In electrophilic addition of alkenes if two or more products can be formed which one will be formed and give the order
The most stable carbocation will be formed it’s know as positive inductive effect
Tertiary
Secondary
Primary
How can we test for a double bond
By addition of bromine water which it will be decolourised
What is meant by addition
A reaction that converse a double bond into a single bond
How can plasticisers modify polymer properties
They force polymer chains apart meaning they can slide over each other ie pvc
Why are polyalkenes unreactive and why is this a problem
They have strong polar c-c and c-h bonds and it means they are hard to dispose of
How is l density polyethene made
By being polymerised at high temperatures and pressures and branched polymers are produced
What are the properties of Low density polyethene
Low density
Flexible
Stretch well
Branches chains don’t
What is low density polyethene used for
Plastic bags sheeting insulation cable
