It has been a few years since Addison Ault published his commentary in this Journal(1) arguing for an appropriate role for recipes in the undergraduate organic laboratory.1 Jerry Mohrig (2) has also argued that while getting students to design their own procedures is an important goal, this goal is particularly hard to achieve in the organic laboratory, where complex techniques are involved.
A recent conversation with an organic lab student reminded me of why following recipes is often not straightforward for students. This student was attempting to scale down and replicate an Organic Syntheses procedure (permanganate oxidation of piperonal to piperonylic acid) (3). The procedure called for washing the manganese dioxide byproduct with hot water. Not having ever seen manganese dioxide before, the student was confused by the word wash. To him, wash referred to the extracting or mixing of an organic layer with an aqueous layer in a separatory funnel. The workup also called for three separate filtrations, one hot and at an alkaline pH, one cold and at an alkaline pH, and one at an acidic pH (to remove manganese dioxide, piperonal, and piperonylic acid, respectively). The chemistry involved in these steps was fairly straightforward, but nonetheless was highly confusing to the student. He did not understand the purpose of each step and therefore did not know what pH would be alkaline enough or acidic enough.
This laboratory exercise turned out to be a excellent learning experience for this student. But what struck me most about it was how much thinking and understanding was required of the reader in order to just follow the recipe. To an experienced chemist, an Organic Syntheses procedure is fairly easy to follow. But to an inexperienced student, it is quite complex. I was reminded by this student that the problem with asking students to follow recipes is not in giving students procedures to follow, but in giving them dumbed down procedures in which no thinking is required. Our goal for the organic laboratory should be to design better experiments in which some scaffolding (4) is provided to students, but some information is left for them to figure out for themselves.
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