Hydroformylation of Olefins with Synthesis Gas

On the other hand, the oxidative coupling reaction of CH4 in the presence of Og, even when performed in membrane-type reactors, is mainly catalysed by metal oxide catalysts. Also oligomerisation, aromatisation and the partial oxidation to methanol or formaldehyde apply non-metallic heterogeneous catalysts (i.e. zeolites, supported metal oxides or heterogenized metal omplexes). The reader is therefore directed to some excellent reviews on these subjects. At this point it is perhaps relevant to introduce the formation of carbon nanofibers or nanotubes from methane, these being catalysed by metal nanoparticles, but at the moment this is not considered as a Cl chemistry reaction. Again we direct the attention of the reader to some reviews on this type of process.  

Sol-gel preparation methods offer the possibility of entrapment of the metallic complex. This method has been used for bimetallic Rh-Pd177 and Rh-Co178 systems, with silica employed as the support material. The metallic nanoparticles in these catalysts are very efficient. However, their 

Of the different reactions which employ methane as a reactant, those that lead to formation of syngas by steam or dry reforming and partial oxidation should be mentioned, and these can be considered as indirect methods for 

Methanol is a key compound in Cl chemistry because it allows the conversion of raw materials, from which it is produced, into more valuable organic chemicals. However, the main application of heterogeneous catalysts for the activation of CH3OH is related to their transformation into hydrocarbons. For these technologies, the catalytic reactions are based on the acid-base properties of surfaces, and the catalytic materials consist of zeolites (such 

Ciuparu, M. R. Lyubovsky, E. Altman, L. D. Pfefferle, A. Datye, Catal. 

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Ketone formation as a further major side reaction was noticed by Roelen in the discovery of hydroformylation with ethylene. The name Oxo Reaction was then given to the reaction of olefins with synthesis gas. It was found later that other olefins were much less susceptible to ketone formation and special conditions had to be used to obtain useful yields of ketones. 

Oxo reaction. Reacting an olefin with synthesis gas (CO and H2) to produce an aldehyde (called hydroformylation) followed by hydrogenation (addition of hydrogen), producing an alcohol containing one more carbon than the original olefin. 

Pure compound studies demonstrated (Adkins and Kresk, 7) that certain olefinic compounds reacted exclusively by hydrogenation rather than by hydroformylation, Treatment of crotonaldehyde with synthesis gas and dicobalt octacarbonyl at 125° gave butyraldehyde in about 50% yield. The addition of small amounts of diphenylsulfide to the dicobalt octacarbonyl did not interfere with the hydrogenation. Later it was shown (Wender, Levine, and Orchin, 9) that if the temperature was raised from 125° to 170-185°, crotonaldehyde was reduced to butanol ... 

Hydroformylation. Experiments with supported cobalt catalysts led to the hydroformylation (or 0X0) process for the conversion of olefins and synthesis gas to aldehydes. Homogeneous catalysis followed, and is now used exclusively. The generally accepted mechanism involves the following reactions ... 

Small amounts of hydrocarbons added to the normal tetrahydrofuran or diglyme solvent system result in improved WGSR activity, but larger quantities inhibit the reaction (Table II). When 1-butene or 1-hexene is used, hydroformylation competes with the WGSR (4 ), but the rate of this process is small compared with the rate of H2 production. With pentane, no olefin or aldehyde products could be detected. Calderazzo (29) has reported that Ru(C0) is the principal product when the acetylacetonate of ruthenium is treated with synthesis gas in heptane,... 

Hydroformylation of hetero olefins such as carbonyl compounds is not known to proceed with significant levels of efficiency, whereas the hydroformylation of olefins has been developed to a sophisticated stage. Generally, aldehydes resultant from the latter process exhibit a low propensity to undergo further hydroformylation, with the exception of some activated aldehydes. The rhodium-catalyzed hydroformylation of formaldehyde is the key step in the synthesis of ethyleneglycol from synthesis gas. Chan et al. found... 

All aliphatic olefinic hydrocarbons react with synthesis gas at 100-130° to give, as a principal product, an aldehyde or mixture of isomeric aldehydes containing one carbon atom more than the starting olefin (hydroformylation). If the reaction is conducted at 160-180°, in the presence of a sufficiently large pressure of synthesis gas, the aldehyde... 

Ru(CO)5 is less frequently used than Fe(CO)5 for organic synthesis or as a starting material as a zero-valent ruthenium complex because of its ease of decomposition to Ru4(CO),2 [99]. Dodecacarbonyltriruthenium is very useful for these purposes. It has been showm to be an active catalyst for the hydrogenation of olefins [100], carbonyla-tion of ethylene [101], hydroformylation of alkenes [102], water-gas shift reaction [103], and reduction of nitro groups [104], and recently, C—H bond activation [105] and coupling of diynes with CO [106]. 

Hydroformylation of olefins. Hydroformylation (oxo process) is the oldest homogeneous catalysis of industrial importance. Whereas the combination of an olefin with H2 gives hydrogenation products, a mixture of H2 and CO, called synthesis gas, instead gives various products including hydrocarbons, methanol, ethylene... 

The interest of alkyne and allene hydroformylation is the formation of a,) -unsamrated aldehydes, which are valuable intermediates in fine chemical and pharmacy. In contrast to alkenes, the studies on the hydroformylation of alkynes are relatively scant. The first case of acetylene hydroformylation was reported by Natta and Pino in 1951 [79]. It was found that in the presence of metallic cobalt at 120-150°C and 200-300 atm, acetylene reacted with synthesis gas yielding a mixture of high-boiling, unidentified products. During the following 40 years, hydroformylation of alkynes to a,/l-unsaturated aldehydes had little success [80-85]. The early investigations usually resulted in low selectivity and/or low yield of unsaturated aldehydes, primarily because the formation of the corresponding saturated aldehydes and non-carbonylated olefins could hardly be suppressed. 

Acetylenes are much less adapted to hydroformylation than olefins. Very few examples are reported in the literature. Roelen reported [23] that acetylene reacted with synthesis gas in the presence of cobalt even at low pressure (10 atm, 140-150 °C) the primary reaction was the formation of acrolein. 

Synthesis gas is an important intermediate. The mixture of carbon monoxide and hydrogen is used for producing methanol. It is also used to synthesize a wide variety of hydrocarbons ranging from gases to naphtha to gas oil using Fischer Tropsch technology. This process may offer an alternative future route for obtaining olefins and chemicals. The hydroformylation reaction (Oxo synthesis) is based on the reaction of synthesis gas with olefins for the production of Oxo aldehydes and alcohols (Chapters 5, 7, and 8). 

Synthesis gas is also an important building block for aldehydes from olefins. The catalytic hydroformylation reaction (Oxo reaction) is used with many olefins to produce aldehydes and alcohols of commercial importance. 

Rhodium and cobalt carbonyls have long been known as thermally active hydroformylation catalysts. With thermal activation alone, however, they require higher temperatures and pressures than in the photocatalytic reaction. Iron carbonyl, on the other hand, is a poor hydroformylation catalyst at all temperatures under thermal activation. When irradiated under synthesis gas at 100 atm, the iron carbonyl catalyzes the hydroformylation of terminal olefins even at room temperatures, as was first discovered by P. Krusic. ESR studies suggested the formation of HFe9(C0) radicals as the active catalyst, /25, 26/. Our own results support this idea, 111,28/. Light is necessary to start the hydroformylation of 1-octene with the iron carbonyl catalyst. Once initiated, the reaction proceeds even in the... 

Raffinate-II typically consists of40 % 1-butene, 40 % 2-butene and 20 % butane isomers. [RhH(CO)(TPPTS)3] does not catalyze the hydroformylation of internal olefins, neither their isomerization to terminal alkenes. It follows, that in addition to the 20 % butane in the feed, the 2-butene content will not react either. Following separation of the aqueous catalyts phase and the organic phase of aldehydes, the latter is freed from dissolved 2-butene and butane with a counter flow of synthesis gas. The crude aldehyde mixture is fractionated to yield n-valeraldehyde (95 %) and isovaleraldehyde (5 %) which are then oxidized to valeric add. Esters of n-valeric acid are used as lubricants. Unreacted butenes (mostly 2-butene) are hydroformylated and hydrogenated in a high pressure cobalt-catalyzed process to a mixture of isomeric amyl alcohols, while the remaining unreactive components (mostly butane) are used for power generation. Production of valeraldehydes was 12.000 t in 1995 [8] and was expected to increase later. 

Tables l.I2a and 2.12b offer a variety of economic data concerning the production of hydrogen from different feedstocks, as ell as that of synthesis gas in an H CO molar ratio ranging from 1 1 to 3 1. In fact, the techniques employed to produce pure hydrogen can be exploited to adapt the composition of Hj/CO gas mixtures, so as to use them in specific conversions like those giving rise to certain alcohols (see Sections 9.3 and 9.4) by olefin hydroformylation. Table 1.12c gives details about processes for the elimination of add gases obtained starting with natural gas and coal.

Treatment of 1-alkenes with a cobalt catalyst under high pressures (100-200 atm) of synthesis gas (CO -I- H2) at 120-150°C (catdytic hydroformylation) seldom leads to the isolation of isomerized olefins even when the reaction is interrupted before all of the olefin disappears. The appearance of the formyl group on a carbon atom other than those involved in the carbon-carbon double bond of the starting alkene arises because of successive 1,2-addition-eliminations, which move the cobalt down the chain without dissociation of coordinated HM. That such a sequence of reactions occurs was demon-... 

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