Chapter 12: Alkanes Flashcards
Properties and reactions
1
Q
What are alkanes?
A
saturated carbon chains where carbon atoms are bonded by σ-bonds
2
Q
How does b.p of straight chain alkanes vary with chain length?
A
Increasing b.p with chain length due to greater contact area for London forces to take effect.
3
Q
What is the effect of branching on b.p of alkanes?
A
b.p decreases due to reduced contact area.
4
Q
Is the C-H bond polar?
A
Essentially no as their electronegativity is so similar.
5
Q
How do alkanes react with halogens?
A
Radical substitution from exposure to UV light
6
Q
What is the mechanism for halogenation of an alkane?
A
Initiation: x₂ → 2x• Propagation: CH₄ + x• → •CH₃ + Hx •CH₃ + x₂ → CH₃x + x• Termination: 2x• → x₂ etc...
7
Q
What type of substitution is most likely in an alkane?
A
Substitution which forms the highest order carbocation.
