Partial racemisation is known to occur in Sn1 reactions, but why does Sn2 reaction also show little racemisation?

  • $\begingroup$ Because it's not really a binary thing - real processes are somewhere in between $\mathrm{S_N1}$ and $\mathrm{S_N2}$. $\endgroup$
    – Mithoron
    Commented Mar 21 at 15:07
  • $\begingroup$ Your question is a potentially good one, but the way of asking it can be many times better. Please include supporting resources, your research work and the source from where you read it. As such, your question is too vague to be answered. $\endgroup$ Commented Mar 21 at 15:08

1 Answer 1


If this is a question you've been asked to answer, it is a poor one. SN2 reactions (as they are generally understood) don't show racemisation at all, but some reactions are a mixture of SN1 and SN2 as outlined by Mithoron.

That said, I recently read this paper which blew my mind a little:

Backside versus Frontside SN2 Reactions of Alkyl Triflates and Alcohols

It leads to a more general point: should we think of SN2 reactions in terms of kinetics (i.e. second order nucleophilic substitutions) or mechanistically (i.e. backside attack into a low-lying σ*)? It so happens that the two definitions usually correspond, but I suppose this isn't necessarily the case.

But I'm certain the answer they were looking for was "because it does SN1 too, a bit".


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