Photolysis ketones

Figure C2.3.9. Product distribution of dissymmetrical ketone photolysis as influenced by cefyltrimethylammonium chloride (CTAC) micelles. The initial ketone, A(CO)B is photolysed to lose the carbonyl group and to produce tliree products, AA, AB and BB. These data are for benzyl (A) 4-methylbenzyl (B) ketone. Product AA is 1,2-diphenylethane, product BB is 1,2-ditolylethane and product AB is l-phenyl-2-tolyl-ethane. At low CTAC concentration, in the absence of micelles, a random distribution of products is obtained. In the presence of micelles, however, the AB product is heavily favoured. Adapted with pennission from 1571.

An extensive series of low-temperature matrix isolation experiments has failed to provide any evidence of oxirene formation, either by diazo ketone photolysis (82CB2192) or by attempted photo-retro-cycloaddition (82CB2202). 

A singlet precursor has, however, been proposed for 4,4,4-triohloro-2-methyl-1-butene (17) produced in the photolysis of isomesityl oxide (18) in carbon tetrachloride solution on the basis of its all-emission spectrum (DoMinh, 1971). There remains some ambiguity, however, about the detailed route by which 17 is formed. Moreover there is other evidence suggesting that ketone photolysis in carbon tetrachloride is different CI3C. CHaCiMe) CHa CH3. CO. CHa. C(Me) CHa... 

At levels of nonmethane hydrocarbons where their reaction rates with HO are a significant fraction of the reaction rate of HO with CO and methane, it may happen that the clean-air HO concentration remains unchanged. This would result if the increase in HO removal by NMHC s is compensated by increasing HO sources such as aldehyde or ketone photolysis and reactions such as R21. These considerations are examined below. 

The importance of the stereoelectronic conformation in determining the path of reaction may be seen in the example of phenyl cyclobutyl ketone. Photolysis of this compound yields 60% of the highly strained bicyclopentane shown below and only 40% of open-chain olefin(84) ... 

Ketone photolysis in an inert atmosphere has been widely studied--ft 5-Q. Apart from polymer photooxidation studies, however, little work has been done on their degradative irradiation in an oxidizing medium51 53. 

For this reason we have concentrated on the study of ketone photolysis in the presence of oxygen and the interaction of the oxygen-centered radicals arising in this reaction with certain tetramethylpiperidine derivatives. ... 

Diisopropyl ketone photolysis under exclusion of oxygen... 

Diisopropyl ketone photolysis in the presence of oxygen and IZNO as additive... 

Also in the case of a polymer therefore, provided the acyl peroxy radicals are formed by ketone photolysis in the presence of oxygen, the oxidation of amines by these radicals would make a significantly greater contribution to stabilization than the nit-roxide. The latter is in any case present in only very small amount as secondary producti - -. 

The acyl radicals formed in ketone photolysis are excited and, therefore, rapidly splits into CO and alkyl radical (in the gas phase). Since aldehydes and ketones are products of oxidation, continuous hydrocarbon photooxidation is an autoaccelerated process. 

Photodecarbonylation of p-tolyl benzyl ketone Photolysis of dibenzyl ketones with CuCl2 scavenger... 

In this chapter we will review the recent advances of supramolecular photon chirogenesis in various confined media, excluding micelles, chiral solvents, liquid crystals, metal complexes, polymer matrices, clays, and crystals. Micelles are typical supramolecular assembly with an internal hydrophobic core which shows a unique boundary effect, e.g., enhanced radical recombination of geminate radi-cal pairs produced by ketone photolysis [26], but essentially no asymmetric photon-... 

Here, R CHO represents intermediate organic species, typically including aldehydes and ketones. Photolysis of NO2 results in the formation of atomic oxygen (O), which reacts with atmospheric O2 to form ozone ... 

THE ROLE OF THE EXCITED SINGLET AND TRIPLET STATES (SUPERSCRIPTS S AND T, respectively) IN PRIMARY PROCESSES II AND III FOR KETONE PHOTOLYSIS W-PENTANE AND n-HEXANE SOLUTIONS... 

---