alkenes (organic) Flashcards
what is an alkene?
Unsaturated hydrocarbons with a C=C bond
General formula of an alkene?
CnH2n
Why is there no rotation about the C=C bond?
Due to the pi orbital - electron density above and below the single bond, which holds the carbon atoms in place
Are they more or less reactive than alkanes? Why?
More reactive due to high electron density of the double bond and the fact that the pi bond is slightly easier to break
What intermolecular forces of attraction do they have?
Only van der Waals due to non-polar bonds
Are they soluble in water? Why?
No, non-polar (van der Waals < hydrogen bonding)
Name and describe the 2 kinds of isomers alkenes can have
Chain isomers (branched chains)
Position isomers (C=C on different carbon atom)
Geometric E-Z isomers (Z is when 2 highest atomic number chains are on the same side of the double bond and E is when they are on opposite sides)
What is an electrophile?
Electron deficient atoms/ions which accept a pair of electrons (from the C=C bond)
What is the most stable kind of carbocation intermediate? Why?
Alkyl groups have a positive inductive effect, so the most stable carbocation is the one bonded to the most other carbon atoms (i.e. tertiary carbocation)
Major products will be formed from which kinds of carbocations?
Tertiary
What conditions are needed for the electrophilic addition of h2O to an alkene?
Acid catalyst, usually phosphoric acid
What are the products of the electrophilic addition of h2o to an alkene?
an alcohol
What conditions are needed for the electrophilic addition of a hydrogen halide to an alkene?
room temp
What conditions are needed for the electrophilic addition of a halogen molecule to an alkene?
room temp and organic solvent
How does a molecule with a non-polar bond react as if it is an electrophile?
C=C double bond with a high electron density induces a temporary dipole in the halogen molecule - beta+ atom attracted to double bond