Intermediates Produced in the Flash Photolysis of Acetone and Amides in Aqueous Solution

Authors: M. Nakashima, E. Hayon

The flash photolysis of air-free aqueous acetone solutions was shown to produce CH2COCH3 and (CHg^COH radicals. The acetonyl CH2COCH3 radical has an absorption maximum at 295 nm and an extinction coef- ficient 6295 = 800 ± 150 M-1 cm-1. No intermediates could be observed in the flash photolysis of air-free aqueous amide solutions. In presence of acetone, photosensitized decomposition of amides has been observed. Formamide (F), N,N-dimethylformamide (DMF), acetamide (A), N-methylacetamide (NMA), and N,N- dimethylacetamide (DMA) have been examined, and the transient species produced in the presence of acetone have been observed. These species are produced by H-atom abstraction by triplet excited acetone. With the IV-methylated amides, abstraction takes place mainly from the iV-methyl group producing HCONCHKCHa), CH3CONHCH2, and 3 0 2( 3) radicals. With F and A, the main radicals are CONH2 and CH2CO- NH2. It is interesting to note that the site of H-atom abstraction by triplet acetone is the same as that recently found for abstraction by OH radicals. This correlation is further discussed.

https://doi.org/10.1021/J100682A002