PHOTOCHEMISTRY OF ACETONE

Gierczak, T., J. B. Burkholder, S. Bauerle, and A. R. Ravishankara, Photochemistry of Acetone under Tropospheric Conditions, Chem. Phys., 231, 229-244 (1998). 

The photochemistry of acetone is perhaps more complicated than that of any other ketone, because the rates of all the chemical and physical reactions of its excited states are closely competitive. Since... 

The photochemistry of acetone has been studied chiefly over the spectral range 2537 to 3130 A. The temperature has been varied from 0 to several hundred °C. The primary process in this wavelength region is almost solely... 

The photochemistry of ketones in the presence of exocyclic olefins has not yet been systematically studied. Chung and Ho reported the photochemistry of acetone in the presence of several exocyclic olefins. Surprisingly, homoalkylation occurred resulting in a series of 4-cycloalkylbutan-2-ones (with quantum yields of 0.14 0.01) rather than the expected Paterno-Buchi reaction (Sch. 33). With perdeuterated acetone, the photocycloaddition path increased due to the primary kinetic isotope effect (as shown for products 108 and 109, respectively, from 2-methyleneadamantane 107) [105]. 

Aloisio S, Francisco JS (2000) The Photochemistry of Acetone in the Presence of Water, Chem. Phys. Lett. 329 179—184. 

A laser flash study of the photochemistry of acetone has examined the polarization induced by irradiation. The author suggests that this study shows the... 

Chung, W. S. and Ho, C. C., Photochemistry of acetone in the presence of exocyclic olefins an unexpected competition between the Photo-Conia and Paterno-Buchi reactions, /. Chem. Soc., Chem. Commun., 317,1997. 

As discussed in Chapter 6.J, acetone photochemistry is of interest because this ketone is distributed globally, has both biogenic and anthropogenic sources, and has been proposed to be a significant source of free radicals in the upper troposphere. The absorption cross sections of acetone (as well as other aldehydes and ketones) are temperature dependent at the longer wavelenths, which is important for application to the colder upper troposphere. Figure 4.29, for example, shows the absorption cross sections of acetone at 298 and 261 K, respectively (Hynes et al., 1992 see also Gierczak et al., 1998). 

The photochemistry of biacetyl has been extensively studied, both in the vapor phase and in solution. In the vapor phase the products include carbon monoxide, ethane, methane, acetone, ketene, and 2,3-pentanedione. It has been shown that the primary process is cleavage of the carbon-carbon bond between the two carbonyl groups to yield acyl radicals, which on further reaction give the observed products.14,43... 

From the photolysis of cyclopentanone in the presence of O218 an upper limit of 0.03 has been estimated for the quantum yield for the formation of cyclopentanone-018 (33). This may be compared with the quantum yield of 0.45 for acetone-O18 formation under identical conditions (39). It has been suggested (but not established) that the reaction between acetone and 021S takes place with the triplet state of the molecule. On this basis, the low efficiency of the corresponding reaction in cyclopentanone has been interpreted to favor the idea that a triplet excited state is not important in the photochemistry of cyclopentanone. 

R = H) is singlet in character, the photochemistry of 64 was studied by Griffin et al.36 Direct irradiation of 64 at 254 or 350 nm in benzene or acetone gave the phenanthrol 296 in essentially quantitative yield. Thermolysis of 64 at 200°C, however, yielded the isomeric phenanthrol 297. 

The photochemistry of l,4-bis(pentamethyldisilanyl)butadiyne in the presence of methanol, acetone and acetaldehyde has also been investigated50. 

The deMayo-type photochemistry of 1,3-dioxin-4-ones has been beautifully applied by Winkler et al. to the synthesis of complex natural products. Substrate 133 gave under sensitized irradiation (with acetone as cosolvent) product 134 as single diastereoisomer (Scheme 6.47). The diastereoselectivity results from cyclic stereocontrol exerted by the two stereogenic centers in the spiro-bis-lactone part of the starting material. After installation of the furan, saponification and bond scission in a retro-aldol fashion generated a keto carboxylic add, which produced the natural product ( )-saudin (135) by simultaneous formation of two acetal groups [128]. 

Dougherty TP, Grubbs WT, Heilweil EJ. Photochemistry of Rh(CO)2 (acetyl-acetonate) and related metal dicarbonyls studied by ultrafast infrared spectroscopy. J Phys Chem 1994 98 9396-9399. 

Further studies on the photochemistry of friedelin have led to the isolation of the unsaturated aldehyde (130).105 Silver oxide oxidation of (130) gave the known putranjivic acid. Irradiation of friedelin in the presence of acetone afforded the hydroxy-ketone (131).106 Photochemically initiated reaction of 7/3-hydroxyfriedelane and 3/3,7/3-dihydroxyfriedelane with lead tetra-acetate-iodine... 

Photodecomposition. Owing to its simple structure and great importance as a model compound, there have been many studies of acetone photochemistry. The bulk of this work has been reviewed earlier (148,175). The photodecomposition of acetone has shown the major products to be carbon monoxide, ethane, and methane. Under proper conditions, other minor products are produced. 

Photodecomposition. Since the last review of photochemistry of HFA (61), there has been a great deal of effort expended in the study of the primary processes and decomposition modes of HFA. The photodecomposition products observed appear to be carbon monoxide and hexafluoroethane exclusively. The trifluoroacetyl radical, CF3CO, must be very unstable. As in acetone, it has been proposed that the decomposition processes must overcome an energy barrier, as temperature-dependent quantum yields were observed (252). A detailed mechanism that takes into account a vibrational deactivation cascade has been proposed by several authors (34,35,97,252). 

The photochemistry of more complex and highly substituted alkenic partners has been studied. In 1978, Hartmann and coworkers reported the photocycloaddition of 4-oxazolin-2-one with acetone, used as a photosensitizer in the reaction of 4-oxazolin-2-one with alkenyl and alkynyl partners, to form oxe-tane (44). Recently, Scharf has described the photochemistry of 3-acetyl-2,3-dihydio-2,2-dimcthyloxa-zole (45). Irradiation of (45) in the presence of acetophenone produced the oxetane (46) with the phenyl group endo (17%), in addition to 21% of a ring-opened derivative. The stereoselectivity is in agreement with the high exo carboxyl selectivity observed in the photocycloaddition of methyl phe-nylglyoxylate with 2,2-dimethyl-1,3-dioxole to produce oxetane (47). 

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