Chapter 13 Alkenes Flashcards
What are alkenes?
Unsaturated hydrocarbons that contain at least one carbon to carbon double bond in their structure
What is the general formula of an alkene?
CnH2n
Describe how a C==C is formed using p-orbitals
p-orbitals overlap above and below the plane of the carbon-carbon bond forming a pi-bond and a sigma bond
how is a Pi-bond formed?
From the sideways overlap of two p-orbitals, one from each carbon atom of the double bond
What are stereoisomers?
Same structrual formula but a different arrangement of the atoms in space
What conditions must a molecule satisfy to have an E/Z isomerism?
A C==C double bond
Different groups attached to each carbon atom of the double bond
What is cis-trans isomerism?
A special case of E/Z isomerism and to occur one of the attached groups on each carbon atom in the double bond must be hydrogen
When is an isomer “cis”?
A cis isomer has the hydrogen atoms on each carbon in the double bond on the same side of the molecule
When is an isomer “trans”?
A trans isomer has the hydrogen atoms diagonally opposite each other in the double bond
What are the Cahn-Ingold-Prelog rules?
A system where each group in the double bond is given a priority based upon their atomic number
If the groups of higher priority are on the same side then the compound is a Z isomer
If the groups of higher priority are diagonally placed across the double bond, the compound is an E isomer
How do you test for unsaturation?
Any compound containing a C==C double bond will decolourise bromine water
How do you turn an alkene into an alkane?
Via Hydrogenation
- react with hydrogen
- Nickle catalyst
- 423K
How do you turn an alkene into a haloalkane?
React with X2 at room temp where X is a halogen
How do you turn an alkene into an alcohol?
React with steam in the presence of a phosphoric acid catalyst
What is an electrophile?
An atom or group of atoms that are seeking electrons
