An Ultrafast Time Resolved Infrared and Computational Study of the Photochemistry of Ethyl 2‐Diazo‐3,3,3‐Trifluoropropanoate (CF ₃ CN ₂ CO ₂ Et)

The photochemistry of ethyl 2‐diazo‐3,3,3‐trifluoropropanoate (CF 3 CN 2 CO 2 Et) was studied in solution at ambient temperature with femtosecond (fs) time‐resolved infrared (IR) spectroscopy. Experimental results are interpreted with the aid of quantum mechanical calculations. The upper singlet excited state S n of CF 3 CN 2 CO 2 Et decays by three processes: internal conversion to the ground state, fragmentation to the singlet carbene, and diazirine formation. The singlet carbene then subsequently decays to triplet carbene or reacts with the solvent. In methanol‐D (MeOD), typically a proficient scavenger of singlet carbenes, the carbene‐alcohol ylide was produced. The analogous CH 3 CN‐ylide of the singlet carbene is produced when the photolysis is performed in acetonitrile, while in CHCl 3 , the C–Cl insertion product was detected.