rate at which methanol or chloride ion appears in the solution.
2) The initial rate of the reaction is measured.
- The rate of the reaction depends on the concentration of methyl chloride and the
concentration of hydroxide ion.
- Rate equation: Rate ∝ [CH 3 Cl] [OH–] ⇒ Rate = k [CH 3 Cl] [OH–]
i) k is the rate constant.
- Rate = k [A]a [B]b
i) The overall order of a reaction is equal to the sum of the exponents a and b.
ii) For example: Rate = k [A]^2 [B]
The reaction is second order with respect to [A], first order wirth respect to [B],
and third order overall.
- Reaction order:
- The reaction is second order overall.
- The reaction is first order with respect to methyl chloride and first order with
respect to hydroxide ion.
- For the reaction to take place a hydroxide ion and methyl chloride molecule
must collide.
- The reaction is bimolecular –– two species are involved in the
rate-determining step.
- The SN2 reaction: Substitution, Nucleophilic, bimolecular.
6.7 A MECHANISM FOR THE SN 2 REACTION
- The mechanism for SN2 reaction:
- Proposed by Edward D. Hughes and Sir Christopher Ingold (the University
College, London) in 1937.
