Alkenes Flashcards
What are stereoisomers?
Compounds with the same structural formula but a different arrangement in space
What is E/Z isomerism?
Stereoisomerism in terms of restricted rotation around a C=C double bond
What special part is needed in the name of an alkene?
En or Ene
What is the name of the main bond and the secondary bond in a double bond?
Main bond = Sigma bond
Secondary bond = Pi bond
How does a pi bond form?
The sideways overlap of two P orbitals
Which bond is weaker, sigma or pi?
Pi bond
What do the CIP rules state about E/Z isomerism?
The group with a larger atomic mass on the end of a bond is the higher priority group.
What do E and Z mean in E/Z isomerism?
E = Entgegen = Apart = Opposite sides Z = Zusammen = Together = Same sides
What are the four addition reactions of alkenes and what are their conditions?
- Addition of Hydrogen - Nickel catalyst
- Halogens (i.e Cl2) - RTP
- Hydrogen Halide (e.g. HBr)
- Addition of Water - Phosphoric acid catalyst
What is the mechanism of addition to alkenes and how is it shown?
Electrophilic addition
- Line from double bond to delta positive charge atom, and line from the molecule’s bond to the delta negative atom
- Line from the electron pair on the negative ion
- Complete new product
What does electrophile mean?
Attracted to pairs of electrons
What does Markownikoff’s rule state?
The non-hydrogen atom goes to the carbon with most carbons attached
How is atom economy calculated?
Mr of desired product
———————————- x 100
Sum of Mr of all products
How is percentage yield calculated?
Actual amount
————————— x 100
Theoretical amount
How does addition polymerisation work?
Multiple small monomers
