The new signs bringing greater understanding to organic chemistry

Until a few years ago, Deaf students and sign language interpreters in Christina Goudreau Collison’s chemistry class at Rochester Institute of Technology (RIT) in the US would fingerspell terms like S_N2 for a bimolecular nucleophilic substitution reaction. Now, they move their hands in a fluid movement to indicate how starting materials transform via a transition state into the final product.

Besides S_N2 reactions, conventional organic chemistry textbooks name several other reaction pathways including unimolecular nucleophilic substitution (S_N1), unimolecular elimination (E1) and bimolecular elimination (E2). Goudreau Collison says there are five major mechanisms in organic chemistry that haven’t yet been formally named. That’s why she and her team created a sign they call syn-3, which models the transition state and intermediate when a brominium bridge forms across a π bond, for example. The same syn-3 sign can also be used when describing oxymercuration, epoxidation and cyclopropanation since all have similar transition states.