Formation of carbonyl compounds

Ouyang, J. et al. (1980). Formation of carbonyl compounds from beta-carotene during palm oil deodorization. J. Food Sci. 43 1214-1222. 

Acids catalyze the decomposition of secondary hydroperoxide with the formation of carbonyl compounds [46,83]. 

Treatment of Fischer-type carbene complexes with different oxidants can lead to the formation of carbonyl compounds [150,253]. Treatment with sulfur leads to the formation of complexed thiocarbonyl compounds [141]. Conversion of the carbene carbon atom into a methylene or acetal group can be achieved by treatment with reducing agents. Treatment of vinylcarbene complexes with diborane can also lead to demetallation and formation of diols [278]. The conversion of heteroatom-substituted carbene complexes to non-heteroatom-substituted carbene complexes... 

Ih Formation of carbonyl compounds and alterations of hyaluronic acid in lung Rabbit 26... 

In an earlier report, Maitlis et al. showed that 1 could be easily converted into a hydrido complex [Cp lrHCl]2 (2) under ambient conditions by treatment with alcohol and a weak base (Scheme 5.1) [19], probably accompanied by the formation of carbonyl compounds. This fact means that the hydrogen atom in an alcohol can be rapidly transferred to the iridium center in the form of a hydride but then, if the hydride on the iridium could be re-transferred to another hydrogen acceptor, a new catalytic system using alcohols as substrates might be realized. In fact, a wide variety of Cp Ir complex-catalyzed hydrogen transfer systems using alcohols as substrates, and based on the above hypothesis, have been reported to date [20]. 

Other indices measure a secondary stage of oxidation, such as the anisidine value (ANV), pointing to formation of carbonyl compounds, capable of undergoing condensation reactions with p-anisidine, and the thiobarbituric acid reactive substance (TBARS) pointing to the presence of malondialdehyde (MDA) in particular. In biological systems, TBARS is of widespread use as a measure for the extent of oxidation damage. Another test for stability of oils to oxidation is based on the development of acidity as secondary product, for example, standards using the Rancimat equipment or a similar setup. 

Olefins participate in a variety of oxidation reactions which lead to the formation of carbonyl compounds, gums, and high-molecular-weight deposits... 

Scheme 12.2 Intermediate stages of the Maillard reaction showing the formation of carbonyl compounds...

Similarly, oxidation of alkenes resulting in the formation of carbonyl compounds through the cleavage of the carbon-carbon double bond [Eq. (12.8)] can be considered as a metathetic transformation ... 

Kieber, R. J., X. Zhou, and K. Mopper. 1990. Formation of carbonyl compounds from UV-induced photodegradation of humic substances in natural waters Fate of riverine carbon in the sea. Limnology and Oceanography 35 1503-1515. 

Oxidations of alcohols with water-free Cr(VI) reagents, such as the ones in rows 3-5 in Table 17.5, always result in the formation of carbonyl compounds. In particular, a carbonyl compound is obtained even if it is an aldehyde and therefore in principle could be oxidized to give the carboxylic acid. On the other hand, aldehydes are oxidized further (rows 1 and 3 in Table 17.5) if one uses water-containing Cr(VI) reagents (e. g., oxidations with K2Cr207 in sulfuric acid) or the Jones reagent (unless the latter is used under really mild conditions). Fig-... 

Fig. 1. a-Oxidation of amino acids. Hydroxyl radical (or other reactive radical) abstracts hydrogen atom from the a-carbon. The C-centered free radical formed may react with other amino acid residues or dimerize in the absence of oxygen, which leads to protein aggregation. In die presence of oxygen the carbon-centered radical forms peroxyl radical. Reduction of peroxyl radical leads to protein hydroperoxide. Decomposition of hydroperoxide leads to formation of carbonyl compounds via either oxidative deamination or oxidative decarboxylation. Oxidation of the new carbonyl group forms a carboxyl group. 

Compounds 85a-c were treated with bromine, which resulted in rupture of the O-Te bond with the formation of carbonyl compounds 86a-c (Equation 11). For R = Me, bromination of the methyl group occurred to give a mixture of products 87 <1996T3365>. 

Most of what known about chromium catalysis is rather empirical in naturebut seems to fit within this picture. For example, in sharp contrast to manganese, chromium catalyst appears to favor the formation of carbonyl compounds. This tendency is likely to be related to the ability of chromium ions to participate in two-electron change (heterolytic) redox reactions [77, 78] in addition to the one-electron change (homolytic) reactions noted above. These heterolytic reactions can involve both hydroperoxides and alcohols. 

Detailed mechanisms accounting for the formation of carbonyl compounds have also been postulated. ... 

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