Hydroformylations, olefins

Olefin-CO coploymers Olefin p-complexes Olefin Fibers Olefin hydroformylation Olefin hydrogenation Olefimc alcohols Olefin isomerization Olefin metathesis Olefin oligomers Olefin oxides... 

Usually, high-purity CO is manufactured on a large scale by means of costly cryogenic separation or absorption from syngas. The above approach could be attractive for small production. Also based on Equations 14 and 15, an easy source of oxogas (C0 H2 = 1 1) can be imagined. Indeed, we could demonstrate that methyl formate and methanol can be used to hydroformylate olefins in good yields and selectivities (37). 

It is reasonable to assume that prior to the exclusive use of chemicals derived from feedstocks other than crude oil, chemicals based on crude oil and chemicals based on alternate feedstocks will supplement each other. This situation has already arisen as is exemplified in the use of coal derived CO/H2 to hydroformylate olefins originating from mineral oil. For instance, in West-Germany Hoechst converts coal into CO/H2 which is used to prepare alcohols from naphtha derived olefins. Table IV summarizes a number of additional reactions in which this point is especially emphasized. 

As a result of the recognized role of transition metal hydrides as l reactive intermediates or catalysts in a broad spectrum of chemical reactions such as hydroformylation, olefin isomerization, and hydrogenation, transition metal hydride chemistry has developed rapidly in the past decade (J). Despite the increased interest in this area, detailed structural information about the nature of hydrogen bonding to transition metals has been rather limited. This paucity of information primarily arises since, until recently, x-ray diffraction has been used mainly to determine hydrogen positions either indirectly from stereochemical considerations of the ligand disposition about the metals or directly from weak peaks of electron density in difference Fourier maps. The inherent limi-... 

Example 11.1. Hydroformylation of cyclohexene with phosphine-substituted cobalt hydrocarbonyl catalyst. The most probable network of cyclohexene hydroformylation catalyzed by a phosphine-substituted cobalt hydrocarbonyl is shown on the facing page. HCo(CO)3Ph (cat) is in equilibrium with the CO-deficient HCo(CO)2Ph (cat ) and CO. For greater generality, quasi-equilibrium of these species with the 7r-complex, X, is not assumed. Actual hydroformylation olefin — aldehyde proceeds via a Heck-Breslow pathway (cycle 6.9 that includes the trihydride, X2) but without... 

Phosphine-modified cobalt catalyst is applied commercially only in the Shell process to hydroformylate olefins of medium chain length (C7-C14). The resulting alcohols are sold under the brand name Dobanol . 

From reaction (b), a new carbon-carbon bond is formed by the intermediacy of the transition metal. Several chemical processes in which new carbon-carbon bonds are formed (e.g., hydroformylation, olefin polymerization, homologation of alcohols, the Fischer-Tropsch reaction) are rationalized by a common mechanism of carbon chain growing. Much discussion and scientific work is under way to ascertain the general applicability of these findings to specific chemical or biochemical processes however, a basic understanding of the elementary steps involved in insertion reactions will lead to a better understanding of known reactions and to the development of new reactions. 

Rhodium complex Hydroformylation Olefin + products Sodium n-dodecyl 79... 

Rhodium complex Hydroformylation Olefin+ Sodium n-dodecyl sulfate 7-120 > 79... 

The formylation reaction is a mixed success. While the coupling of aryl, vinyl, or allyl halides (triflates) is effective, quite often the conditions are harsh. The formylation of alkyl halides or hydroformylation olefins and acetylenes with palladium is not the method of choice for preparing the corresponding aldehydes. 

Phase-separation techniques are particularly useful for hydroformylation. Olefin hydroformylation is the process in which the application of the phase-separation technique and hydrophilic phosphine ligands was first realized on an industrial scale. Rhone-Poulenc and RuhrChemie claim to have manufactured an average 300000 tons of butyric aldehyde per year by biphasic... 

The linear a olefins described m Section 14 15 are starting materials for the preparation of a variety of aldehydes by reaction with carbon monoxide The process is called hydroformylation... 

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. 

Hydroformylation of an olefin usiag synthesis gas, the 0x0 process (qv), was first commercialized ia Germany ia 1938 to produce propionaldehyde from ethylene and butyraldehydes from propylene (12). 

Often the aldehyde is hydrogenated to the corresponding alcohol. In general, addition of carbon monoxide to a substrate is referred to as carbonylation, but when the substrate is an olefin it is also known as hydroformylation. The eady work on the 0x0 synthesis was done with cobalt hydrocarbonyl complexes, but in 1976 a low pressure rhodium-cataly2ed process was commerciali2ed that gave greater selectivity to linear aldehydes and fewer coproducts. 

Aliphatic Aldehyde Syntheses. Friedel-Crafts-type aUphatic aldehyde syntheses are considerably rarer than those of aromatic aldehydes. However, the hydroformylation reaction of olefins (185) and the related oxo synthesis are effected by strong acid catalysts, eg, tetracarbonylhydrocobalt, HCo(CO)4 (see Oxo process). 

Commercial Olefin Reactions. Some of the more common transformations involving a-olefins ia iadustrial processes iaclude the oxo reaction (hydroformylation), oligomerization and polymerization, alkylation reactions, hydrobromination, sulfation and sulfonation, and oxidation. 

The 0x0 process is employed to produce higher alcohols from linear and branched higher olefins. Using a catalyst that is highly selective for hydroformylation of linear olefins at the terminal carbon atom. Shell converts olefins from the Shell higher olefin process (SHOP) to alcohols. This results in a product that is up to 75—85% linear when a linear feedstock is employed. Other 0x0 processes, such as those employed by ICI, Exxon, and BASE (all in Europe), produce oxo-alcohols from a-olefin feedstocks such alcohols have a linearity of about 60%. Enichem, on the other hand, produces... 

Propjiene (qv) [115-07-1] is the predominant 0x0 process olefin feedstock. Ethylene (qv) [74-85-1J, as well as a wide variety of terminal, internal, and mixed olefin streams, are also hydroformylated commercially. Branched-chain olefins include octenes, nonenes, and dodecenes from fractionation of oligomers of C —C olefins as well as octenes from dimerization and codimerization of isobutylene and 1- and 2-butenes (see Butylenes). 

Linear terminal olefins are the most reactive in conventional cobalt hydroformylation. Linear internal olefins react at less than one-third that rate. A single methyl branch at the olefinic carbon of a terminal olefin reduces its reaction rate by a factor of 10 (2). For rhodium hydroformylation, linear a-olefins are again the most reactive. For example, 1-butene is about 20—40 times as reactive as the 2-butenes (3) and about 100 times as reactive as isobutylene. 

Functional Olefin Hydroformylation. There has been widespread academic (18,19) and industrial (20) interest in functional olefin hydroformylation as a route to polyfiinctional molecules, eg, diols. There are two commercially practiced oxo processes employing functionalized olefin feedstocks. Akyl alcohol hydroformylation is carried out by Arco under Hcense from Kuraray (20,21). 1,4-Butanediol [110-63 ] is produced by successive hydroformylation of aHyl alcohol [107-18-6] aqueous extraction of the intermediate 2-hydroxytetrahydrofuran, and subsequent hydrogenation. 

Three significant, commercial processes for the production of amyl alcohols include separation from fusel oils, chlorination of C-5 alkanes with subsequent hydrolysis to produce a mixture of seven of the eight isomers (Pennsalt) (91), and a low pressure 0x0 process, or hydroformylation, of C-4 olefins followed by hydrogenation of the resultant C-5 aldehydes. 

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... 

The switch from the conventional cobalt complex catalyst to a new rhodium-based catalyst represents a technical advance for producing aldehydes by olefin hydroformylation with CO, ie, by the oxo process (qv) (82). A 200 t/yr CSTR pilot plant provided scale-up data for the first industrial,... 

Butylene isomers also can be expected to show significant differences in reaction rates for metaHation reactions such as hydroboration and hydroformylation (addition of HCo(CO). For example, the rate of addition of di(j -isoamyl)borane to cis-2-huX.en.e is about six times that for addition to trans-2-huX.en.e (15). For hydroformylation of typical 1-olefins, 2-olefins, and 2-methyl-l-olefins, specific rate constants are in the ratio 100 31 1, respectively. 

Hydroformylation. Probably the best known catalytic carbonylation reaction is the hydroformylation, or 0x0 reaction, for producing aldehydes and alcohols from carbon monoxide, hydrogen, and olefins (eq. 9) (36). 

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