E-Z isomerism Flashcards
Why does E-Z isomerism occur?
Atoms can rotate freely around a single bond, but there is restricted rotation around a double bond.
What are stereoisomers?
Molecules have the same structural formula but a different arrangement of atoms in space.
What is a substituent of a double bond?
Something other than hydrogen that is bonded to the double bond.
What is a Z stereoisomer?
When the 2 substituents are on the same side of the double bond.
What is an E stereoisomer?
When the 2 substituents are on the opposite sides of the double bond.
Outline the CIP rules
Look at each end of the bond and determine which substituent has priority.
Look at the substituents which have priority and see which side of the double bond they are on.
If two priority substiuents are on the same side, it is a z isomer.
What happens if two atoms bonded on same size of double bond are the same?
Look at the atoms 2 bonds away from double bond.
Atom with highest atomic number takes priority.
When does an alkene show cis-trans isomerism?
If a double bond has 2 substituents, with one on each carbon.
If substituents on same size, it is a cis isomer.
If substituents are on opposite sides, it is a trans isomer.
