ELECTROPHILIC ADDITION Flashcards
What are alkenes? (1)
They are unsaturated hydrocarbons, they have at least one double bond.
Why are alkenes unsaturated? (1)
Molecules with carbon double bonds are unsaturated because they can make more bonds with extra atoms in addition reactions.
What makes alkenes have a high electron density? (1)
Because there are two electrons in the double bond, this makes alkenes reactive.
What happens in electrophilic addition? (2)
1) the double bonds open up and atoms are added to the carbon atoms
2) these reactions occur because the double bond has got plenty of electrons and is easily attacked by electrophiles.
What are electrophiles? (1)
Electrophiles are electron acceptors - they are usually short of electrons, so there attracted to places where there are lots of them.
What are some examples of electrophiles? (2)
-positively charged ions e.g H+ and NO2+
-polar molecules
What test is used to detect insaturation? (1)
We use bromine water.
What colour does bromine water turn if the test is positive? (1)
From orange to colourless.
What is the mechanism for adding bromine water to an alkene? (1)
H2C=CH2 + Br2. -> CH2BrCH2Br
What is a carbocation? (1)
A carbocation is an organic ion containing a positively charged carbon atom
What are the nucleophiles that can be added in electrophilic addition reactions? (3)
-a molecule of bromine
-hydrogen halides
-cold concentrated sulfuric acid
What are the products from an electrophilic addition reaction with a hydrogen halides? (1)
Forms a halogenoalkane
What are the two possible products when a hydrogen halide reacts with an unsymmetrical alkene? (2)
-can form two of; a primary, secondary or tertiary carbocation
What is the carbocation intermediate?
The amount of each product formed depends on how stable the carbocation formed in the middle of the reaction is
What carbocation is most stable?
Carbocation with more alkyl groups are more stable because the alkyl groups feed electrons towards the positive charge, the more stable carbocation is more likely to form.
