Aldehydes alkenic

The yields for reactions of unsubstituted terminal alkenes were lower than for substituted alkenes but they were still reasonable and could be increased further by increasing the aldehyde alkene ratio. Total conversions of substrate were reported with epoxide selectivity as high as 95% in some cases. The FBC system allows for a much higher substratexatalyst ratio (1000 1) than the non-fluorous epoxidation reported (20 1) previously. Recycling the fluorous layer once showed no reduction in conversion or selectivity. 

Nitrogen-containing heterocyclic compounds, including 1,2,3,4-tetrahydroqui-noline, piperidine, pyrrolidine and indoline, are also popular hydrogen donors for the reduction of aldehydes, alkenes, and alkynes [75, 76]. With piperidine as hydrogen donor, the highly reactive 1-piperidene intermediate undergoes trimer-ization or, in the presence of amines, an addition reaction [77]. Pyridine was not observed as a reaction product. 

Co-containing POMs have been found to be among the most efficient catalysts for homogeneous aerobic oxidation and co-oxidation processes [91-93]. This prompted many researchers to design solid Co-POM-containing materials [78,94-100]. Thus, various Co-POMs have been deposited on cotton cloth [94] and silica [100], datively [95] or electrostatically [96,97] bonded to NH2-modified silica surfaces (vide infra) as well as intercalated in LDHs [78,98,99]. The resulting materials were successfully used for aerobic oxidation of aldehydes, alkenes, alkanes, alcohols and some other organic substrates. 

As shown by their redox potentials oxoruthenium(IV) species containing polypyridyl ligands are strong oxidants and they oxidize a variety of substrates. The complex [Ru(0)(bpy)2(py)] has also been used electrocatalytically for the oxidation of alcohols, aldehydes, alkenes, and aromatics." Electrocatalytic oxidation has also been performed on this complex that has been incorporated into poly-4-vinylpyridine. ... 

A gold monohydride species was also suggested in the report by Ito and Sawamura et al. on the dehydrogenative silylation of alcohols by HSiEt3 and a diphosphine gold(I) complex. Reaction was selective for the silylation of hydroxy groups in the presence of alkyl halides, ketones, aldehydes, alkenes, alkynes and other functional groups [193]. 

When the enthalpies of reaction between branched ketones and the corresponding 1,1-disubstituted alkenes are calculated using the multiple enthalpies of formation available for the latter, the following ranges are obtained Me/i-Pr, 196.6 to 200.5 Et/i-Pr, 201.2 to 206.6 and Me/t-Bu, 200.5 to 205.1 kJmol-1. Perhaps it is reasonable to conclude that the reaction enthalpies for the branched compounds either will be approximately constant, as for the unbranched ketone/alkene conversions, or will be more endothermic with branching, as in the branched aldehyde/alkene conversions. In either case, the least endothermic reaction enthalpy for the Me/i-Pr conversion above seems inconsistent and therefore the enthalpies of formation for 2,3-dimethyl-l-butene from References 16 or 26, which are essentially identical, should be selected. These enthalpies were also selected in a previous section. However, there is too much inconstancy, as well as too much uncertainty, in the replacement reactions of carbonyls and olefins to be more definitive in our conclusions. 

Similar reaction pathways have also been found for the oxidation of dimethyl sulfide to dimethyl sulfoxide and dimethyl sulfoxide to dimethyl sulfone by [Ru(bpy)2(py)(0)]2+ with respective rate constants of 17.1 and 0.13 M l s"1 in MeCN at 298 K (48). The complex [Ru(bpy)2 (py)(0)]2+ has also been used electrocatalytically for the oxidation of alcohols, aldehydes, alkenes, and aromatics (23, 49). The kinetics of oxidation of formic acid/formate ion by [Ru(bpy)2(py)(0)]2 +, with a large kinetic isotope effect [ HC02-/ADCo2- = 19 (25°C, /r = 1.0 M)], has been reported (50). A two-electron hydride transfer has been suggested for the oxidation of HC02 by [Ru(bpy)2(py)(0)]2+. A similar mechanism has also been suggested for the oxidation of alcohols (51) and aromatics (52) by [Ru(bpy)2(py)(0)]2+ and other related Ru(IV) oxo complexes (28,... 

Although the Wittig reaction (section 4.3.1) and its modified versions provide highly effective and general methods for the aldehydes and ketones alkenation, there are several drawbacks in their use. To overcome these drawbacks, new methods which employ the transition metal complex reagents " as catalysts have been developed. A variety of catalytic aldehyde alkenation reactions have been reported with Mo catalyst other metals such as Re, Ru, Rh and Fe are also established as useful catalysts. Very mild conditions are required for catalytic alkenation short reaction times and high selectivities are generally observed. 

Among the various organics that can be successfully decomposed by the activated sludge process include proteins, polysaccharides, fats, oils, aldehydes, alkenes, aromatics, halogenated hydrocarbons, and isoalkenes. 

The alkoxy radical undergoes p-scission on the C—C bond, with the formation of an aldehyde and alkyl or vinyl radical. A general reaction scheme with the formation of volatile aldehyde, alkene, and alcohol is illustrated in Figure 1 (6). 

Many reactive species emitted by the snowpack such as NO, NO2, HONO, aldehydes, alkenes and hydrocarbons are produced by photochemical reactions. 

The aldehyde alkene substrate 101 [Eq. (24)] was found to cyclize to an epimeric mixture of cis-decalin derivatives 102 and 103. Similarly, acyclic substrate... 

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