Author (Your Name)

Xi YangFollow

Date of Award


Document Type

Honors Thesis (Open Access)


Colby College. Chemistry Dept.


Dasan M. Thamattoor

Second Advisor

Rebecca R. Conry


In this study, the synthesis and properties were explored of the compound methylphenylvinylidene (MPV), a vinylidene carbene with methyl and phenyl groups as substituents. A phenanthrene-based precursor, 1-(1-phenylethylidene)-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene, was synthesized in three steps and was subjected to photolysis in C6D6 at ambient temperature. During photolysis, the MPV carbene rearranged into 1-phenylpropyne via a 1,2-phenyl shift, instead of 1,2-methyl shift, confirmed by photolysis of 13C-labeled precursor. This experimental result is consistent with computational results using the CCSD(T)/cc-pVTZ//B3LYP/6-31+G* method. The calculations suggest that the 1,2-phenyl shift in singlet carbene requires 3.8 kcal/mol to overcome the barrier, whereas the 1,2-methyl shift needs 11.9 kcal/mol. The generation of MPV carbene was confirmed by trapping with cyclohexene, which gave a carbene-alkene cycloadduct, with a yield of 1.5%. The identity of the trapped product was confirmed by the authentic sample of the trapped adduct, which was synthesized in three steps starting from cyclohexene. Additionally, upon photolysis, 11% of the precursor rearranged into a mixture of E- and Z- cycloheptatriene derivatives.