(24c) Reactivity of Singlet Oxygen Generated Using Nanoporous Silicon for Transformation of Acrylonitrile

Crystalline nanoporous silicon (PSi) mediated generation of singlet oxygen is by far one of the most efficient photoexcitation processes with up to 80% quantum efficiency. The singlet oxygen is effective in breaking double bonds (-ene type) between two carbon atoms and also bonds between heteroatoms. This singlet oxygen, however, is short lived (~few milliseconds). Depending on the reaction media and other quenching reactions, it leaves many unknown parameters related to reaction chemistry, kinetics, and electron transfer processes. Our research focuses on testing the hypothesis that the excitons generated on PSi are sufficiently reactive to break the double and triple bonds (C=N and N=N; C?kN and N?kN) present in an organic molecule. Thus, the singlet oxygen potentially offers selective transformation of functional groups in complex molecules. Also, singlet oxygen based chemistry is one of the less-exploited strands of green chemical technologies. Only a small number of photochemical or photocatalytic processes have been commercialized on a large scale due to limited understanding of the reaction chemistry and other mass transfer limiting parameters. Understanding the degradation and transformation mechanisms and pathways will foster development of efficient processes for mitigation of Army waste streams prior to introduction of munitions compounds into service. The presentation will focus on preliminary results of our experimental studies on transformations of acrylonitrile (C=N and C?kN) using singlet oxygen generated on PSi.