Alkanes and the Halogenation of Alkanes Flashcards
What are alkanes?
Simple covalent molecules
What forces do alkanes have?
weak intermolecular forces, London forces - they are non-polar as C and H have similar electronegativities
How does chain length affect the boiling point of alkanes?
- C chain increases
- more e-
- London forces are stronger
- more energy to overcome
- higher bp
How does branching affect the boiling point of alkanes?
- branches increase
- less surface points of contact
- London forces work over longer distances
- London forces are weaker
- Less energy to overcome
- Lower bp
What are the three stages of free radical substitution?
Initiation, Propagation, Termination
What is the initiation stage for Chlorine reacting with methane?
Cl2 – UV light -> 2Cl*
What is the propagation stages for Chlorine reacting with methane?
Cl* + CH4 –> HCl + *CH3
Cl2 + CH3 –> Cl + CH3Cl
What is the termination stages for Chlorine reacting with methane?
2Cl* –> Cl2
Cl* + CH3 –> CH3Cl
2CH3 –> C2H6
What are the limitations of free radical substitution?
- multiple organic products
- monosubstitution
- polysubstitution
What is monosubstitution?
Many possible mono-substituted products because of many carbon sites in pentane (when the halogen doesn’t go on the end carbon)
What is polysubstitution?
More than one hydrogen is substituted for a halogen
What bonds are in alkane shapes and how are they formed?
sigma (sideways 6) - strongest covalent bond - head on overlaps of orbitals
How does the C-X bond affect the rate of hydrolysis?
The lower the C-X bond enthalpy, the faster the rate of hydrolysis
