Halogenoalkanes: Nucleophilic Substitution - Reactivity of Halogenoalkanes

Question 1

What decides the reactivity of halogenoalkanes?

Answer 1

• The carbon-halogen bond strength or enthalpy decides the reactivity
• Carbon-halogens bonds of higher enthalpies react slower during nucleophilic substitution reactions

Question 2

How does reactivity change down the halogens?

Answer 2

• Reactivity increases as you descend

Question 3

What other factor can affect the reactivity of halogenoalkanes in nucleophilic substitution reactions?

Answer 3

• Polarity of the C-X bond

• Difference in electronegativity values between C and X
• Would predict fluoroalkanes to be most reactive as the carbon δ+ has largest positive charge
• So is therefore more easily attacked by nucleophiles