I’m writing my dissertation right now, and as a result I’m going back through a lot of old slides and references to fill in details that I left out for publication. One interesting question that I’m revisiting is the following: when protonating benzaldehyde, what is the H/D equilibrium isotope effect at the aldehyde proton? This question was relevant for the H/D KIE experiments we conducted in our study of the asymmetric Prins cyclization.