Details

Autor(en) / Beteiligte

• Tokihiro, Jodie
• Fitzpatrick, Caralyn
• Platz, Matthew S.

Titel

Wavelength‐dependent photochemistry of 1‐phenyl‐1‐diazopropane

Ist Teil von

• Journal of physical organic chemistry, 2022-11, Vol.35 (11), p.n/a

Ort / Verlag

Bognor Regis: Wiley Subscription Services, Inc

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 1‐Phenyl‐1‐diazopropane (PDP) was photolyzed in acetonitrile/methanol mixtures using either 520‐nm light or 350‐nm light. The main photoproducts were 1‐methoxypropylbenzene and E,Z‐1‐phenylpropene. With 520‐nm light, a plot of (1‐methoxypropylbenzene)/(E,Z‐1‐phenylpropene) versus methanol concentration was linear. These results are consistent with the visible light induced fragmentation of PDP to dinitrogen and closed shell singlet (S0) ethyl, phenylcarbene (1EPC) which partitions between 1,2 hydrogen migration to form alkene, and reaction with methanol to form ether. The same plot generated with 350‐nm light significantly deviates from linearity. It is proposed that 350‐nm light generates the carbene in a vibrationally excited, open shell S1 excited state (1EPC*). This state rearranges to E,Z‐1‐phenylpropenes in competition with relaxation to ground state 1EPC over a few tens of ps. As a result, methanol cannot completely suppress alkene formation upon photolysis of PDP with 350‐nm light. The carbene excited state is a “non‐trappable carbene” route to alkenes. The photochemistry of 1‐phenyldizopropane is wavelength dependent, indicating that an open‐shell singlet carbene excited state is formed with shorter wavelength light. That state isomerizes to alkene in competition with relaxation to closed shell singlet. The excited carbene is not trappable with methanol.