Organic Chemistry: Change, Part 5 - The Illustrated SN1 Reaction

 Greetings,

This post provides an illustrated example of the SN1 reaction.  The drawing shows the formation of an alcohol from the nucleophilic attack of a tertiary brominated hydrocarbon by water. A "stick" structure of the hydrocarbon is used for easier viewing of the brominated hydrocarbon structure.

Water removes the bromine atom in step 1 and two separate water molecules are involved in Step 2.  Step 1 is the slower step, therefore it determines the overall reaction rate. Step 2 happens very fast because a carbocation is a very reactive entity. The overall rate of reaction is fast for the SN1 type because a) the bromine is connected to a tertiary carbon atom (a more stable tert. carbocation results) and b)  bromine atom is reletively easy to remove because it is more stable (than lighter, smaller halogens) because of its large size.  A larger atom provides for a distribution of charge over a larger volume, which results in greater stability (greater number of instantaneous charge-distribution states, due to larger size, increases strength of London Dispersion Forces).

That's all for now.  As always, thank you for reading!

This has been a publication of http://LearningChemistryEasily.blogspot.com