Date of Award


Document Type

Honors Thesis (Open Access)


Colby College. Chemistry Dept.


Dr. Dasan M. Thamattoor


Previous studies have shown that the photolysis of phenanthrene-based cyclopropyl precursors can generate carbenes. In this work, a novel phenanthrene precursor was synthesized and photolyzed to generate the dimethylalkylidene carbene, which was subsequently trapped by cyclohexene. The car- bene was not prone to an internal rearrangement as some other carbenes are, and instead favored the intermolecular addition reaction. The precursor also underwent a rearrangement via pericyclic processes. A theoretical analysis of the potential energy surface of the system is presented using coupled cluster and density functional methods. Preliminary analysis for the precursor via time-resolved laser flash photolysis (LFP) was performed. Future experiments include more comprehensive LFP studies on this system in addition to experiments to isolate the elusive rearrangement to 2-butyne. This work provides a safe and synthetically viable route to generate and trap alkylidene carbenes. These alkylidene carbenes provide interesting opportunities to study the migratory aptitudes of various substituents, and provide a fascinating plethora of opportunities to study such intermediates both experimentally and theoretically.


carbenes, organic chemistry, photochemistry, alkylidenes, ketenes, dipheylketene, dimethylalkylidene