Alkenes Flashcards
Name two useful ways of disposing of polymers
Combustion for energy production; organic feedstock to make new plastics or other products
How are addition polymers made?
Poly(name of original alkene)
Reacting an alkene with bromine makes what?
A dibromo-alkane
What is the order of stability of primary, secondary and tertiary carbocations?
primary lowest secondary middle and tertiary highest. Tertiary > secondary > primary
Identify a hazard of burning PVC - poly(chloroethene)
Releases toxic HCL gas
When can you have cis/trans isomers as well as E/Z?
When one of the bonded substituents on each C is the same e.g. each has a Cl
Can double bonds rotate?
No- because pi bond would break if p orbitals not aligned
What is the shape and bond angle around the C atom in an alkene?
120 degrees, trigonal planar
How does stability of carbocation relate to the major and minor product in electrophilic addition of HX?
Major product is formed from the more stable carbocation
What is the structure of the repeat unit of poly(propene)
-CH2CH(CH3)-
What it added to an alkene to make an alcohol?
Steam, with acid catalyst - e.g. phosphoric acid
How does a pi bond form?
Sideways overlap of adjacent p orbitals above and below the bonding atoms.
What are the two requirements for E/Z isomerism?
C=C double bond, and two different groups bonded to each of the carbons.
What is Markownikoffs rule?
When HX reacts with an unsymmetrical alkene, the H bonds to the C of the alkene which has more H already bonded
Which monomer makes the polymer which has (CH2CHCl) as its repeat unit?
chloroethene
Name two types of sustainable polymers being formulated by chemists
Biodegradable and photodegradable polymers
What is the test and positive result for an alkene
Decolourises bromine water
In the electrophilic addition mechanism, what type of fission does the pi bond undergo?
Heterolytic fission - to form ions
Describe a C=C double bond
One sigma bond and one pi bond
Reacting ethene with hydrogen and Ni catalyst makes what?
Ethane
How do the Cahn-Ingold-Prelog rules for identifying E/Z isomers assign priority?
Higher priority = higher atomic numbers
Define an electrophile
An electron pair acceptor
What type of mechanism do alkenes tend to react in e.g. with bromine
Electrophilic addition
How can HCl gas from burning PVC be removed from waste mixture?
Neutralise with a base - e.g. sodium carbonate
