3.3.3. Alkenes Flashcards
What is an alkene?
A hydrocarbon with a carbon-carbon double bond
Why are alkenes described as unsaturated?
They have a carbon-carbon double bond
Describe the electron density of the double bond
It is a region of high electron density
What type of stereoisomerism can alkenes exhibit?
E-Z isomerism
What physical feature of alkenes causes their stereoisomerism?
That the double bond cannot rotate
What two type of reactions do alkenes typically undergo?
Electrophilic addition or polymerisation
What type of reagents do alkenes react with?
Electrophiles
Which three reagents do alkenes typically react with in an electrophilic addition reaction?
HBr, H?SO? and Br?
What are the products of an electrophilic addition reaction with Br??
A dibromoalkane
Why is bromine water used as a test for alkenes?
The Br? reacts with the alkene so its reddish-brown colour is decolourised
What are the products of an addition reaction with HBr?
A bromoalkane
What is a carbocation intermediate?
An intermediate molecule in a reaction which has a positive charge on a carbon atom
Place the orders of carbocation in order of stability from most to least
Tertiary > secondary > primary
What is the name of the effect that stabilises carbocations?
Alkyl inductive effect
Which carbocation forms the major product in an addition reaction with HBr?
More stable carbocation
