Ch.13 Alkenes
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When naming do you prioritise the double bond or an alkyl or halogen substituent
Double bond
What is a pi bond
Covalent bond formed from the sideways overlap of 2 adjacent P orbitals creating an area of electron density above and below the plane of the molecule, each carbon contributes 1 electron
What is a stereoisomer
Same molecular formula and same structural formula, yet different arrangement of the atoms in space
What is needed for an E/Z isomer
. C=C bond . Each C must be bonded to 2 different groups
What is needed for a cis-trans isomer
. C=C . Both C must be bonded to 2 different groups, but one group must be common to both carbons
what is a Cis isomer
Common group on same side of C=C
what is a Trans isomer
Common group on opposite side of C=C
In E/Z isomers each C attached group is given priority based on their what
Atomic number
An E isomer is when
2 highest priority groups are on opposite sides of the C=C (Entgegan)
A Z isomer is when
The 2 highest priority groups are on the same side of the C=C
When assigning priority you look for the
First point of difference
Why are alkenes reactive
Relatively low bond enthalpy of the pi bond. the pi electrons are more exposed as they are above and below the plane.
How could you test for unsaturation
Alkenes react with bromine water- colour change from orange to colourless Alkanes don’t react with bromine water so there won’t be a colour change
Markownikoffs rule
The H will attach its self to the C of the C=C with the most hydrogens
What degree of carbocation is the most stable and why
Tertiary because alkyl groups are electron donating. Each alkyl group push electrons towards the cation. the + charge is spread out making it more stable.
The major product is
The product with the most stable carbo cation intermediate
Alkenes undergo polymerisation at
High temp and pressure using a catalyst
what is the bond shape around the c in a c=c bond
trigonal planar 120*
what does unsaturated mean
at least 1 c=c
explain the cahn-ingold-prelog rule for naming E-Z isomers
each atom attached to the c of a c=c bond is given priority based on its atomic number. if the 2 highest priority are on the same side it is a Z isomer and the oposite would be an E isomer.
how do you assign priority when naming E/Z isomers
start with the atoms directly bonded if same atomic number move on until you find the first point of difference.
what is the difference between the primary and secondary carbocation
primary- has + charge on end of chai. secondary- has + charge in middle of chain.
how can u recycle PVC
dissolve in a solvent then recover by precipitation, solvent can be used again.
what is feedstock recycling and give an advantage
chemical/thermal process of regaining monomers from waist polymers. it produces raw materials for the production of new polymers. can be done with unsorted unwashed polymers.