A week ago, one of my students sent me this in an email:

“I have a question for you: when an ester and an alkoxide anion are together in a problem, how do we know if a transesterification or a Claisen condensation will take place? Is it just that if the alkoxide anion is the same as the ether group (so a transesterification would reproduce the base)?”

Here is what I wrote back to him:

“Both will occur…they will compete. Transesterification might be faster, but it is reversible. Claisen condensation might be slower, but it is irreversible. So what will happen is the OR groups from the initial ester and from the added base will scramble, and eventually all of the product will be from Claisen condensation.”

In his next email to me, he wrote my three favorite words to hear from a student: “That makes sense!”

This time of the year, I tend to hear those words a fair amount from students. I think students are asking more of these types of questions because the material is at its most intricate. I attribute their understanding of my explanations largely to the way in which the material has been organized since the first semester: foundational principles are presented before reactions are introduced, and students are taught the common elementary steps and the rules for reasonable mechanisms before they are held accountable for predicting products. With a continued focus on these kinds of things as new reactions are introduced, students develop an expectation that they should understand what is going on at all times, and they ask questions when they don’t.

Years ago, when I was teaching organic chemistry under a functional group organization, it was common for me to see blank stares on students’ faces. Now, with the way things are going in my class, perhaps it’s just a matter of time before the following three words are regularly spoken by my students: “I love organic!”

-Joel Karty

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