The Purpose of this experiment is to characterize the 405 nm photoproducts of deuterated biacetyl. It is hypothesized that one or more enol (2-hydroxy-1-butene-3-one) conformers of biacetyl could be produced following photolysis within a frozen gas matrix.
Initially, numerous methods for the production of deuterated biacetyl are discussed. Following the deuteration process, numerous experiments were conducted using varying concentrations of deuterated biacetyl within a variety of frozen gas matrices. The resulting data showed that, regardless of the concentration of deuterated biacetyl or the matrix gas implemented, that ketene, and not enol is produced in the greatest concentrations. Carbon monoxide, methane, and methylcarbene acetate are observed as minor photoproducts, with no detectable amount of enol being produced at all.
Several theoretical mechanisms for the production of ketene were proposed. However, due primarily to energy limitations of the reaction conditions within the matrix, it is concluded that the most likely mechanism for ketene production is via a secondary photolysis reaction. An initial photolysis occurs whereby biacetyl dissociates into two acetyl radicals. The secondary photolysis of an acetyl radical produces methyl radical and carbon monoxide. Ketene is produced following a deuterium abstraction from an acetyl radical by a methyl radical.
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