Photofragmentation primary

These results were explained by the discovery that the chloro-ruthenium complexes are not the primary photoproducts under CO in 1.0 M CCl /octane solution. Instead Ru(CO>5 proved to be the initial product even after nearly complete photofragmentation of the starting material, and the chlorocarbonyl ruthenium products to be the result of a secondary, dark reaction between the Ru(C0)5 and CCI4 (3) ... 

Table 1. Photolysis and Biodegradation, of Polymers that Undergo Primary Photofragmentation.

The photofragmentation of thiophene on irradiation at 193 nm has been studied <1995JPC1760>. The primary products are vinylacetylene, acetylene, thioketene, and sulfur (Equations 1 and 2). 

When radical pairs are produced by a cleavage of ketones, and the loss of CO is prevented on energetic grounds, fragments of the reactions of the primary radical pair become important. Deoxybenzoins (15)30) or adamantyl ketones (20)25,30) provide examples of such systems. The photodecomposition of l,2-diphenyl-2-methyl-pro-panone (15)30) illustrates an example of a photofragmentation in reaction (Scheme VIII). The ratio of the major products are highly dependent on solvent environment. For example, the photochemistry of this compound in acetonitrile or benzene yields... 

However, as seen in Scheme 38, block copolymers are accompanied by a relevant amount (30-87%) of homopoly(MMA), due to the contemporary formation of benzoyl radicals by photofragmentation. Minor amounts (1-20%) of homopoly(styrene) are also found, due to the recombination of polymeric benzyl-type primary radicals. 

Photofragmentation is the principal primary process of excited aliphatic nitro compounds subsequently producing N02 and the corresponding radicals (entry 8), which may recombine to form nitrites. The excited nitroalkanes or nitroarenes can also be photoreduced in the presence of a hydrogen-atom donor (entry 9). 

Previous studies show that upon absorption of a UV photon by CH3SSCH3, the primary decomposition is S-S bond scission to produce 2 SCH3 radicals [11,24,26,27]. The recent 248-nm photofragmentation study of Lee et al. [53] confirms this conclusion ... 

The first direct examination of primary photoproducts of thiophene at 193 nm has been made in a recent laser photofragmentation TOF mass spectrometric experiment [175], In this experiment, six product channels were identified, as summarized by processes 70-75 in decreasing order of importance ... 

Table 1 Common examples of photoinitiators that undergo primary photofragmentation processes...

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