Alkenes Flashcards
(16 cards)
What are the sources of alkenes?
- Elimination of halogenoalkanes
- Cracking of alkanes
- Dehydration of alcohols
DCEu
What sort of reaction is hydrogenation?
Addition of hydrogen
heterogenous catalysis
What are the condition for hydrogenation?
250 C
Nickel/ Pt catalysts
nickel is solid
What forms as a result of addition of halides?
(mechanism included)
Halogenoalkanes
What mechanism does addition of halide involve?
Electrophilic addition
involves heterolytic fission
hydrogen added is electrophile( partial positive charge)
State Markovnikov’s rule .
an electrophile adds to an unsymmetrical alkene so that the most stable carbocation is formed as an intermediate
negative part goes to carbon with least hydrogen
What’s an electrophile?
Electron poor species
Conditions to be an electrophile
positive charge
Partial or complete
What’s a Nucleophile?
Electron rich
attracted to nucleus; ability to donate electrons
What are conditions to be a nucleophile?
- lone pair on centrak atom
- multiple bonds between same atoms ( pi bonds)
NH3, H2O, OH-, Cl-, CN-
How many products does electrophilic addition of assymetrical alkene gives?
More than 1 product
What are characteristics of a carbocation?
- positively charged carbon
- makes 3 bonds
Enlist the types of carbocation.
- Primary: 1 R-group
- Secondary: 2 R-groups
- Tertiary: 3 R-groups
What’s true for all nucleophiles?
It donates a lone pair of electrons
