Intro & Examples of Alkenes Flashcards
Does alkenes occur naturally?
Yes, alkenes occur naturally in the animal and plant kingdom.
Give 4 examples of alkenes which occur naturally in the plant and animal kingdom?
Ethene = plant hormone
Muscalure = housefly pheromone (attracts)
Limonene = citrus fruit
α-pinene = conifers (trees)
Give an example of an alkene naturally occurring as a plant hormone?
Ethene = plant hormone
Give an example of an alkene naturally occurring as housefly pheromone?
Muscalure = housefly pheromone (attracts)
Give an example of an alkene naturally occurring in citrus fruit?
Limonene = citrus fruit
Give an example of an alkene naturally occurring in conifers?
α-pinene = conifers (trees)
Where does ethene naturally occur in?
A form of alkene = plant hormone
Where does muscalure naturally occur in?
An alkene = housefly pheromone
Where does limonene naturally occur in?
An alkene = citrus fruit
Where does α-pinene naturally occur in?
An alkene = conifers (trees)
What shape does alkene compounds have and why?
Planar shape bc of sp2 hybridised carbon atom.
What is the bond angle around C atom in alkenes and why?
Bc of sp2 hybridised carbon atom, alkenes end up with a planar shape and the bond angles around C atom becomes 120°.
What types of bonds make up the “double” bond in alkenes and how many are there?
Double bond in alkenes = 1 sigma bond & 1 pi bond.
Why do alkenes give rise to geometric isomerisms?
Bc alkenes have limited rotation around double bond = resulting in geometric isomers.
What are the identifiable characteristic bands of alkenes in the infra red spectra?
sp2 C-H stretch at about 3100 - 3000 cm-1
sp3 C-H stretch at about 3000 - 2900 cm-1
C=C stretching at about 1650 cm-1 (middle, weak band bc…)
