The three dimensional nature of organic molecules is a topic that all organic chemistry courses must cover. Chairs, Newman projections, Fischer projections, rotations, conformational changes, and stereochemistry are very challenging for sophomore students to grasp—especially if this is their first exposure to the concept that structure is a key element to reactivity. That said, watching students take the stereochemistry exam is very entertaining! The students problem-solve by rotating the paper to “see” a perspective better, hold up their hands and rotate them to visualize stereocenters, and even turn pages over to better view the mirror image. It is a rare opportunity for a faculty member to see student problem-solving in real time.
I imagine that stereochemistry is one of the biggest challenges for any textbook author to tackle. Any approach is going to, by the very nature of a text, commit to a singular process of solving problems of “what is the relationship between these two molecules?” Karty has chosen the path of asking students to visualize these relationships. This requires students to see, really see, that two molecules are mirror images of one another if they are enantiomers. For many of my students, with practice, they are able to picture these compounds and solve the problem. The examples in Karty are excellent, and I find that most of these students respond positively to the visuals in the text. However, I have found that there is always a subset of students, about 40% for me, that are unable to mentally manipulate molecules with confidence. In my twenty years of teaching, I have also found that this mental manipulation is not an accurate measure of overall success in organic chemistry, chemistry in general, or further pursuits that lie in other disciplinary areas.