How does temperature affect SN1 reactions?

1 Answer
anor277
Mar 20, 2017

A rise in temperature should accelerate a bond-breaking reaction......

Explanation:

Of course, temperature increase generally increases the rate of most chemical reactions, however, for a typical #S_N1# reaction, we may invoke the following elemental step:

#RCH(X)R'rightleftharpoonsRC^+HR' +X^-#

And this is the rate determining step of the reaction.........

And because this, the rate determining step, involves BOND-BREAKING, we would predict that an increase in temperature should result in the production of more #RC^+HR# species, and thus an INCREASE in the rate of reaction..........

Another way to look at this is to include heat, i.e. #Delta#, as a virtual reactant.............

#RCH(X)R' +DeltarightleftharpoonsRC^+HR' +X^-#

If we raise the temperature, we supply #Delta#, and, therefore, we should drive the equilibrium to the RIGHT as shown.

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