Lead—oxygen bonds reactions with

Sorbic acid is oxidized rapidly in the presence of molecular oxygen or peroxide compounds. The decomposition products indicate that the double bond farthest from the carboxyl group is oxidized (11). More complete oxidation leads to acetaldehyde, acetic acid, fumaraldehyde, fumaric acid, and polymeric products. Sorbic acid undergoes Diels-Alder reactions with many dienophiles and undergoes self-dimerization, which leads to eight possible isomeric Diels-Alder stmctures (12). 

The initial step is the protonation of the aldehyde—e.g. formaldehyde—at the carbonyl oxygen. The hydroxycarbenium ion 6 is thus formed as reactive species, which reacts as electrophile with the carbon-carbon double bond of the olefinic substrate by formation of a carbenium ion species 7. A subsequent loss of a proton from 7 leads to formation of an allylic alcohol 4, while reaction with water, followed by loss of a proton, leads to formation of a 1,3-diol 3 " ... 

Thiocarbamate (tc, RHNCSO-) is a monodentate ambidentate ligand, and both oxygen- and sulfur-bonded forms are known for the simple pentaamminecobalt(III) complexes. These undergo redox reactions with chromium(II) ion in water via attack at the remote O or S atom of the S- and O-bound isomers respectively, with a structural trans effect suggested to direct the facile electron transfer in the former.1045 A cobalt-promoted synthesis utilizing the residual nucleophilicity of the coordinated hydroxide in [Co(NH3)5(OH)]2+ in reaction with MeNCS in (MeO)3PO solvent leads to the O-bonded monothiocarbamate, which isomerizes by an intramolecular mechanism to the S-bound isomer in water.1046... 

Reaction of (984) with MeLi in the presence of donor ligands such as CO or PMe3 traps the Ni1 species (985), which could be characterized by X-ray crystallography.839 Oxygenation of a related Ni1 complex (S3 Ni(CO) leads to 02 activation and O O bond rupture with formation of a bis(//-oxo)nickcl(I11) complex.184,185... 

Hydrolysis is one of a family of reactions which leads to the transformation of pollutants. Under environmental conditions, hydrolysis occurs mainly with organic compounds. Hydrolysis is a chemical transformation process in which an organic RX reacts with water, forming a new molecule. This process normally involves the formation of a new carbon-oxygen bond and the clearing of the carbon-X bond in the original molecule ... 

The initial step is an oxidative addition of RhCI(PPh3)3 to a C-0 bond of the ester moiety and produces rhodium-carbon and rhodium-oxygen bonds. Adjacent rhodium species can undergo further reaction with the formation of anhydride linkages. This anhydride formation may occur between adjacent pairs of reactants, between pairs in the same chain, or between pairs that are present in different chains. All of these reactions are observed, and in however the last reaction is the one of interest here since this leads to cross-linking and char formation. Rhodium is present in both the chary material and in the soluble fractions. From the reaction pathway in order for rhodium elimination to occur, two rhodium-inserted... 

Oxygen-free reactions of psoralens, when in close proximity to the target, proceed via the first excited states in which the 3,4-and the 4, 5 7r-bonds of the pyrone and furan moieties, respectively, can undergo C4-cyclization reactions with, e.g., unsaturated bonds of lipids, or the C5=C6 double bonds of thymine in DNA. In reactions with DNA the psoralen is believed to intercalate with DNA in the dark. Subsequent irradiation at 400 nm usually leads to furan-side 4, 5 -monoadduct formation, whereas irradiation at 350 nm increases the formation of crosslinks in which the furan and pyrone rings form C4 cycloadducts to thymines on opposite strands [95], Subsequent irradiation of the 4, 5 -monoadducts at 350 nm leads to formation of crosslinks and conversion into pyrone-side 3,4-monoadducts. Shorter wave-... 

The rate of the Ir(III) catalyzed reaction was found to be first-order in [Ir] and [H2DTBC], but independent of 02 concentration in chloroform (56). The mechanism proposed for the reaction (Scheme 4) postulates that the protonation of the hydroperoxo a-oxygen by the hydroxy group of the bonded catechol in Int 1 leads to the formation of H202. The o-qui-none ligand of Int 2 is replaced by the partially coordinated catechol in the next step. In order to comply with the experimental rate law, the rate-determining step needs to be the reaction of the oxygen adduct (B) with catechol. 

In this reaction, only the benzylic carbonate can react readily since cleavage of the benzylic carbon-oxygen bond leads to a stabilized carbocation while no such stabilization would exist for the hypothetical products which would be obtained by cleavage of the phenyl carbonate. The benzylic carbocation intermediate which is formed can either eliminate to the corresponding styrene 4 or recombine with the nucleophilic methanol which is formed by decarboxylation. It is the latter reaction which appears to prevail at room temperature as the ether 2 can be isolated in excellent yield. Subsequent heating in the presence of acid catalyst drives the reaction to the elimination product 6 and free methanol. 

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