Alkenes And alcohols Flashcards
What are alkenes made of?
Carbon and hydrogen so hydrocarbons
Do alkenes have the same number of H’s as each other?
No alkenes with more than one double bond have fewer H’s than the General formula suggests
What do alkenes molecules have?
At least one C=C double covalent bond
Why are alkenes unsaturated?
Because they make more bonds with extra atoms in addition reactions
Why are alkenes pretty reactive?
There are two pairs of electrons in the C=C double bond so has a really high electron density
Electrophilic addition in alkenes?
Double bond open up and atoms are added to the carbon atoms
Electrophiles addition reactions happen because the double bond has got plenty of electrons and is easily attacked by electrophiles
What are electrophiles?
Electron-pair acceptors
Usually short of electron so attracted to areas where there are lots of them
Positively charged ions: H+, NO2+
Polar molecular the delta + is attached to places with lots of electrons
Alkenes General formula
CnH2n
How do you test for unsaturation?
Use bromine water
Description of what happens to make bromine water work?
When you shake an alkene with orange bromine water the solution quickly decolourises goes from orange to colourless. Bromine across C=C double bond to form colourless dibromoalkane
Happens by electrophiles addition
What do you need to do about bromine water mechanism?
Have you learnt it? If not learn it and give this a red.
Carbocation is?
an organic ion containing a positively charged carbon atom
What else do alkenes undergo addition with?
Hydrogen halides to form halogenoalkanes
It forms Bromo…(alkane name)
What if a hydrogen halide is added to an unsymmetrical alkene?
Two possible products
What determines how much of the product is formed?
Depends on how stable the carbocation formed in the middle of the reaction is (carbocation intermediate)
Carbocations with more alkyl groups are more stable because alkyl groups feed electron towards the positive end. More stable carbocation is more likely to form.
