Physical Sciences and Mathematics Commons^™

Part I: Photochemical Generation Of Cyclohexyne From A Hydrocarbon Precursor Part Ii: A Triptycenyl Flower, Daniel Maurer

Honors Theses

Part I

Photolysis of phenanthrene-based methylenecyclopropane derivatives have previously been shown to generate alkylidenecarbenes, which readily rearrange to form alkynes. In this work, we show that photolysis of an analogous cyclic alkylidenecarbene precursor at ambi- ent temperature forms cyclohexyne via the putative cyclopentylidenecarbene, and can be trapped by dienes via a Diels-Alder reaction. Cyclohexyne and other strained cycloalkynes are of much interest to theoreticians and experimentalists alike. Results of coupled-cluster and DFT calculations on the potential energy surface of cyclopentylidenecarbene and the corresponding strained cyclohexyne are also presented. The photochemical generation of cy- clopentylidenecarbene, and thus cyclohexyne, from a hydrocarbon …

Experimental And Computational Study Of Methylphenylvinylidene And Its Rearrangements, Xi Yang

Honors Theses

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 …