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CHEM - 4.1.3 Alkenes > Stereoisomers > Flashcards

Flashcards in Stereoisomers Deck (4)
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1

What are stereoisomers?

- Stereo isomers are compounds with the same structural formula but with a different arrangement in space.
- Some alkenes have stereoisomers because there is a lack of rotation around C=C.
- There are E-isomers and Z-isomers.

2

E/Z isomerism

- This is when the double bonded carbon atoms each have 2 different atoms/groups attached to them and when there is restricted rotation.
- Each of the groups linked to C=C is given priority.
- E-isomers when the priority groups are opposite(E).
- Z-isomers when priority groups are on the (Z)ame.

3

Cis-trans isomerism

- Special case of E/Z isomerism where the 2 carbons in the double bond have at least 1 group in common and the other attached is H.
- Cis-isomer has the 2 identical groups on same side.
- Trans-isomer has the 2 identical groups on opposite sides.

4

Cahn-Ingold-Prelog priority rules

- Highest priority group of each of the C=C carbons is the one which has the atom w/ the highest atomic number DIRECTLY bonded to the carbon atoms.
- If the atoms directly bonded are the same (e.g methyl and ethyl), look at the next atom along in each group.