Alkene also hydrogenation, catalytic

The intercalated catalysts can often be regarded as biomimetic oxidation catalysts. The intercalation of cationic metal complexes in the interlamellar space of clays often leads to increased catalytic activity and selectivity, due to the limited orientations by which the molecules are forced to accommodate themselves between sheets. The clays have electrostatic fields in their interlayer therefore, the intercalated metal complexes are more positively charged. Such complexes may show different behavior. For example, cationic Rh complexes catalyze the regioselective hydrogenation of carbonyl groups, whereas neutral complexes are not active.149 Cis-Alkenes are hydrogenated preferentially on bipyridyl-Pd(II) acetate intercalated in montmorillonite.150 The same catalyst was also used for the reduction of nitrobenzene.151... 

Although these catalytic partial hydrogenations of alkynes may well be regarded as the procedure of choice for (Z)-alkenes,25 other catalytic systems have been explored. These include a sodium hydride-sodium alkoxide-nickel(n) acetate reagent,26 and a sodium borohydride-palladium chloride-polyethylene glycol system.27 Diisobutylaluminium hydride (DIBAL) has also been used for the conversion of alkynes into (Z)-alkenes.28 ( )-Alkenes are formed when the internal triple bond is reduced with sodium in liquid ammonia.29... 

Unsaturated ligands such as alkenes often undergo insertion into M-H bonds to give alkyls or vinyls (equation 23). This is an important step in catalytic alkene isomerization, hydrogenation, hydroformylation, hydrocyanation, and perhaps also hydrosilation, although in this last case, insertion into the M-Si bond may be preferred. This is simply the reverse of the -elimination reaction discussed above. 

Ru(PPh3)3(CF3S03)2], also show catalytic activities for the hydrogenation of alkenes. 

Other Reductions. The (porphinato)irons could realize the reduction of alkenes and alkynes with NaBILj. Various unsaturated carbon-carbon bonds were saturated by meso-tetraphenylporphinatoiron chloride (TPPFe Cl) derivatives (up to 81% yield). Ruthenium(III) complexes also pair with NaBH in the reduction of unsaturated carbon-carbon bonds (as does cobalt boride). In the presence of a catalytic amount of Ru(PPh3)4H2 (0.5-1 mol %) and NaBHj, unsaturated carbon-carbon bonds in a wide variety of alkenes and alkynes were saturated in toluene at 100 Addition of water was required to provide a proton source. Similar systems with RUCI3 in aqueous solution reduce unsaturated bonds under milder conditions. Various unactivated mono- or disubstituted olefins and activated trisubstituted olefins were reduced with RUCI3 (10 mol %) and NaBH4 in THF-H2O at 0 °C to room temperature (eq 36). When the RuCl3-catalyzed reductions of olefins were carried out in aqueous amide solution, unactivated trisubstituted olefins were also hydrogenated. ... 

Grignard also did extensive work in the areas of the terpenes, quantitative ozonolysis of alkenes, aldol reactions, catalytic hydrogenation, and dehydrogenation and cracking of hydrocarbons. ... 

An attractive pathway with a lot of potential uses the transition metal mediated reaction of organic halides with carbon monoxide. Suitable substrates are organic halides capable of oxidative addition to low-valent transition metal compounds. Insertion of carbon monoxide and reductive elimination of an acid halide will complete the catalytic cycle. In tins way it was shown tiiat allyl chloride yields butenoic acid chloride in >80% yield accor g to equation 22)P As well as palladium, rhodium and iridium also act catalytically. It is of no surprise that allylic halides, benzylic halides and aryl halides in particular are readily converted to acid halides. Simple aliphatic halid undergo the oxidative addition step more slowly and, if they cany hydrogen atoms on an sf hybridized C atom in the -position to the halogen atom, may give alkenes via 3-hydrogen elimination. Alkenes can also be converted to acid halides widi carbon monoxide in the presence of transition metal catalysts in solvents such as methylene chloride or tetrachloromethane. ... 

Fischer-Tropsch Process. The Hterature on the hydrogenation of carbon monoxide dates back to 1902 when the synthesis of methane from synthesis gas over a nickel catalyst was reported (17). In 1923, F. Fischer and H. Tropsch reported the formation of a mixture of organic compounds they called synthol by reaction of synthesis gas over alkalized iron turnings at 10—15 MPa (99—150 atm) and 400—450°C (18). This mixture contained mostly oxygenated compounds, but also contained a small amount of alkanes and alkenes. Further study of the reaction at 0.7 MPa (6.9 atm) revealed that low pressure favored olefinic and paraffinic hydrocarbons and minimized oxygenates, but at this pressure the reaction rate was very low. Because of their pioneering work on catalytic hydrocarbon synthesis, this class of reactions became known as the Fischer-Tropsch (FT) synthesis. 

Alkenes are reduced by addition of H2 in the presence of a catalyst such as platinum or palladium to yield alkanes, a process called catalytic hydrogenation. Alkenes are also oxidized by reaction with a peroxyacid to give epoxides, which can be converted into lTans-l,2-diols by acid-catalyzed epoxide hydrolysis. The corresponding cis-l,2-diols can be made directly from alkenes by hydroxylation with 0s04. Alkenes can also be cleaved to produce carbonyl compounds by reaction with ozone, followed by reduction with zinc metal. 

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