Organic Chemistry, "Change", Part 18 - Protonation of an Alcohol (Initial Step of the Dehydrolysis Reaction)

 Greetings,

Protonation of an alcohol is an important reaction: An alkene is produced which can then lead to the production of new compounds via addition reactions.

Protonation of an alcohol occurs when an acid is added to an aqueous alcohol solution.  Most alcohols are aqueous solutions because of the difficulty in completely separating water from pure alcohol via distillation.  However, it should be mentioned that the presence of less water will improve the efficiency of alkene production.  This is because, after the protonation step, water is formed - the attached (to the carbon chain) water molecule comes off leaving behind a carbocation intermediate. The loss of water from the carbon chain is in equilibrium with the two reaction products; an individual water molecule and a highly-reactive carbocation intermediate. The presence of more water in the beginning would tend to drive this equilibrium step in reverse, which reduces the concentration of the important carbocation intermediate.  The overall rate of the reaction would then be slower because the loss-of-water change is the reaction mechanism's rate determining step.  A slower reaction can reduce the product yield within a reasonable time frame.  I will expand on the "loss-of-water" discussion in a future post.

For now, here is what the initial protonation step looks like:

In a future post, I'll discuss how the above reaction intermediate changes to form 2-Butane.

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