Lower olefins, hydroformylation

Hydroformylation of Other Lower Olefins and Dienes - Lower olefins such as 1-butene or 1,3-butadiene are hydroformylated with acceptable rates using Rh/tppts catalysts according to the RCH/RP process. Hoechst AG Werk Ruhrchemie has developed an attractive new process350 for the hydroformylation of raffinate II, a mixture of 1-butene, cis- and /rbutane derived from the C4 stream of naphtha crackers (after removal of 1,3-butadiene... 

Hydr/formyUttion. Swiss chemists recommend rhodium(lII) oxide as catalyst for hydroformylation of olefins. Thus they have prepared cyclohexanecarboxaldchyde (2) in 95% yield from cyclohexene (1). Lower yields were obtained using cobalt catalysts. 

The effectiveness of this secondary reaction K, Fig. 1) depends on the ratio of hydroformylation and readsorption rate constants (j8a/j8r). The effect of intrapellet transport restrictions on alcohol selectivity is shown in Fig. 26a for j8a/j8r = 0.5. These results were obtained for a catalyst with kinetic parameters identical to those used to describe selectivity data on Co catalysts in Figs. 16, 17, and 19. Not surprisingly, transport-limited pellets favor these secondary hydroformylation reactions and alcohol selectivity increases with increasing values of the Thiele modulus (Fig. 26a, curve A). Clearly, olefin hydroformylation pathways are most effective when they compete locally with readsorption and chain initiation at high intrapellet olefin fugacities within transport-limited FT synthesis pellets. Outside pellets, hydroformylation sites use only those few olefins that exit FT catalyst pellets after extensive readsorption and chain initiation (Fig. 26a, curve B). Hydroformylation reactions on these external sites occur at much lower rates, which simply reflect the lower olefin fugacities in the gas phase as a result, such extrapellet sites affect FT and alcohol synthesis selectivity only slightly. 

In summary, cluster-derived catalysts have been widely used in various types of CO-based reactions such as Fischer-Tropsch synthesis, methanol synthesis, hydroformylation, carbonylation, and water-gas shift reactions. The catalytic performances of cluster-derived species are evaluated in terms of higher activities and selectivities for lower olefins and oxygenates in CO hydrogenation, compared with those of metal complexes in solution and conventional metal catalysts (Table XIII). 

Following the recommendations of Manassen [18] the history of biphasic hydroformylation began with work on various water-soluble ligands (Table 1). After this preparatory work on various aspects [30], Kuntz [22, 199] expressed the basic idea of a new generation of water-soluble oxo catalysts with triphenyl-phosphine trisulfonate (TPPT S, as the Na salt, as compared with TPPMS and TPPDS, the mono- and disulfonate) as ligands for a Rh-based oxo process, mainly for the hydroformylation of lower olefins such as propene (eq. (5)). 

The lack of data is obvious and surprising at a time when the Ruhrchemie/ Rhone-Poulenc process has been in operation for more than 20 years. A rigid reaction rate model, established under idealized conditions, becomes complex and complicated when it is transferred to the hydroformylation of lower olefins under conditions relevant to the industrial practice, as the mass transfer phenomena involved in a triphasic system (gas-liquid-liquid) in large reactors have to be taken... 

Cuprous chloride tends to form water-soluble complexes with lower olefins and acts as an IPTC catalyst, e.g., in the two-phase hydrolysis of alkyl chlorides to alcohols with sodium carboxylate solution [10,151] and in the Prins reactions between 1-alkenes and aqueous formaldehyde in the presence of HCl to form 1,3-glycols [10]. Similarly, water-soluble rhodium-based catalysts (4-diphenylphosphinobenzoic acid and tri-Cs-io-alkylmethylam-monium chlorides) were used as IPTC catalysts for the hydroformylation of hexene, dodecene, and hexadecene to produce aldehydes for the fine chemicals market [152]. Palladium diphenyl(potassium sulfonatobenzyl)phosphine and its oxide complexes catalyzed the IPTC dehalogenation reactions of allyl and benzyl halides [153]. Allylic substrates such as cinnamyl ethyl carbonate and nucleophiles such as ethyl acetoactate and acetyl acetone catalyzed by a water-soluble bis(dibenzylideneacetone)palladium or palladium complex of sulfonated triphenylphosphine gave regio- and stereo-specific alkylation products in quantitative yields [154]. Ito et al. used a self-assembled nanocage as an IPTC catalyst for the Wacker oxidation of styrene catalyzed by (en)Pd(N03) [155]. 

The addition of various surfactants and micelle-forming agents in the biphasic hydroformylation of olefins was also considered as a tool for enhancement of the reaction rates (see Section 2.3.4). Whereas the presence of a surfactant leads to a lower droplet size in the dispersed phase, thus increasing the liquid-liquid interfadal area and hence the mass-transfer rate, the formation of emulsions is considered as a maj or drawback of this system. Mass-transfer effects in biphasic hydroformylation of 1-octene in the presence of cetyltrimethylammonium bromide (CTAB) was studied by Lekhal et al. [37]. A mass-transfer model based on Higbie s penetration theory was proposed to predict the rate of hydroformylation in a gas-liquid-liquid system. 

Ethylene (C2), propene (C3), and butane (C4) are usually referred to as the lower olefins. Their solubihty in the aqueous phase is high enough to ensure reaction rate without phase-transfer additives. In the following, we will mainly introduce the appHcation of aqueous-organic biphasic catalysis in the hydroformylation of... 

Rhodium Ca.ta.lysts. Rhodium carbonyl catalysts for olefin hydroformylation are more active than cobalt carbonyls and can be appHed at lower temperatures and pressures (14). Rhodium hydrocarbonyl [75506-18-2] HRh(CO)4, results in lower -butyraldehyde [123-72-8] to isobutyraldehyde [78-84-2] ratios from propylene [115-07-17, C H, than does cobalt hydrocarbonyl, ie, 50/50 vs 80/20. Ligand-modified rhodium catalysts, HRh(CO)2L2 or HRh(CO)L2, afford /iso-ratios as high as 92/8 the ligand is generally a tertiary phosphine. The rhodium catalyst process was developed joindy by Union Carbide Chemicals, Johnson-Matthey, and Davy Powergas and has been Hcensed to several companies. It is particulady suited to propylene conversion to -butyraldehyde for 2-ethylhexanol production in that by-product isobutyraldehyde is minimized. 

Conventional triorganophosphite ligands, such as triphenylphosphite, form highly active hydroformylation catalysts (95—99) however, they suffer from poor durabiUty because of decomposition. Diorganophosphite-modified rhodium catalysts (94,100,101), have overcome this stabiUty deficiency and provide a low pressure, rhodium catalyzed process for the hydroformylation of low reactivity olefins, thus making lower cost amyl alcohols from butenes readily accessible. The new diorganophosphite-modified rhodium catalysts increase hydroformylation rates by more than 100 times and provide selectivities not available with standard phosphine catalysts. For example, hydroformylation of 2-butene with l,l -biphenyl-2,2 -diyl... 

Hydroformylation, or the 0X0 process, is the reaction of olefins with CO and H9 to make aldehydes, which may subsequently be converted to higher alcohols. The catalyst base is cobalt naph-thenate, which transforms to cobalt hydrocarbonyl in place. A rhodium complex that is more stable and mnctions at a lower temperature is also used. 

The most influential parameter in cobalt-catalyzed hydroformylation was found to be carbon monoxide partial pressure. Piacenti et al. (30) showed this to be influential for both a- and internal olefins. Results are detailed in Tables V and VI. The percent of n-aldehyde rose rapidly as the carbon monoxide partial pressure was increased up to 30-40 atm CO further increase had little effect. 1-Pentene clearly gave a higher percentage of straight-chain aldehyde than 2-pentene, but the difference was insignificant in the lower Pco experiments. 

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