Hydrocarboxylation hydroformylation

Ojima, I. Eguchi, M. Tzamarioudaki, M. Transition Metal Hydrides Hydrocarboxylation, Hydroformylation, and Asymmetric Hydrogenation. In Wilkinson, G. Stone, F. B. A. Abel, E. W., Eds., Comprehensive Organometallic Chemistry 2, Vol. 12, Pergamon, Oxford, 1995, Chapter 2. 

In the previous chapters we discussed alkene-based homogeneous catalytic reactions such as hydrocarboxylation, hydroformylation, and polymerization. In this chapter we discuss a number of other homogeneous catalytic reactions where an alkene is one of the basic raw materials. The reactions that fall under this category are many. Some of the industrially important ones are isomerization, hydrogenation, di-, tri-, and oligomerization, metathesis, hydrocyana-tion, hydrosilylation, C-C coupling, and cyclopropanation. We have encountered most of the basic mechanistic steps involved in these reactions before. Insertions, carbenes, metallocycles, and p -allyl complexes are especially important for some of the reactions that we are about to discuss. 

Ojima I, Eguchi M, Tzamarioudaki M. Transition metal hydrides hydrocarboxylation, hydroformylation, and asymmetric hydrogenation. In Ahel EW, Stone FGA, Wilkinson G, Hegedus LS, editors. Comprehensive orgarwmetallic chemistry II. Volume 12. Oxford Elsevier 1995. p 9-38. 

Hydraulic Fluids fluides hydrauliques Hydrocarboxylation hydrocarboxylation Hydroformylation synthese oxo Hydrogenation hydrogenation Hydrol meiasse de glucose Hydrolysis hydrolyse Hydrolysis in Oleochemistry hydrolyse des corps gras... 

C-19 dicarboxyhc acid can be made from oleic acid or derivatives and carbon monoxide by hydroformylation, hydrocarboxylation, or carbonylation. In hydroformylation, ie, the Oxo reaction or Roelen reaction, the catalyst is usually cobalt carbonyl or a rhodium complex (see Oxo process). When using a cobalt catalyst a mixture of isomeric C-19 compounds results due to isomerization of the double bond prior to carbon monoxide addition (80). 

The nickel or cobalt catalyst causes isomerization of the double bond resulting in a mixture of C-19 isomers. The palladium complex catalyst produces only the 9-(10)-carboxystearic acid. The advantage of the hydrocarboxylation over the hydroformylation reaction is it produces the carboxyUc acids in a single step and obviates the oxidation of the aldehydes produced by hydroformylation. 

Most ring syntheses of this type are of modern origin. The cobalt or rhodium carbonyl catalyzed hydrocarboxylation of unsaturated alcohols, amines or amides provides access to tetrahydrofuranones, pyrrolidones or succinimides, although appreciable amounts of the corresponding six-membered heterocycle may also be formed (Scheme 55a) (73JOM(47)28l). Hydrocarboxylation of 4-pentyn-2-ol with nickel carbonyl yields 3-methylenetetrahy-drofuranone (Scheme 55b). Carbonylation of Schiff bases yields 2-arylphthalimidines (Scheme 55c). The hydroformylation of o-nitrostyrene, subsequent reduction of the nitro group and cyclization leads to the formation of skatole (Scheme 55d) (81CC82). 

If cobalt carbonylpyridine catalyst systems are used, the formation of unbranched carboxylic acids is strongly favored not only by reaction of a-olefins but also by reaction of olefins with internal double bonds ( contrathermo-dynamic double-bond isomerization) [59]. The cobalt carbonylpyridine catalyst of the hydrocarboxylation reaction resembles the cobalt carbonyl-terf-phos-phine catalysts of the hydroformylation reaction. The reactivity of the cobalt-pyridine system in the hydrocarboxylation reaction is remarkable higher than the cobalt-phosphine system in the hydroformylation reaction, especially in the case of olefins with internal double bonds. This reaction had not found an industrial application until now. 

The hydroformylation reaction has been the subject of excellent reviews (for example I, 6-8) therefore, the object of this particular treatise is not to provide comprehensive coverage of all aspects. The basic chemistry is presented, along with recent developments of interest as reported in the literature, although not in chronological order. Stereochemical studies (6) are included only when pertinent to another point under consideration. Carbonylations or hydrocarboxylation reactions which produce ketones, esters, acids, esters, or amides are not included (/). Also not included is the so-called Reppe" synthesis, which is represented by Eq. (1). 

Decene was hydrocarboxylated with a [PdClaj/TPPTS catalyst in acidic aqueous solutions (pH adjusted to 1.8) in the presence of various chemically modified cyclodextrins (Scheme 10.11) [18]. As in most cases, the best results were obtained with DiOMe-P-CD. In an interesting series of reactions 1-decene was hydrocarboxylated in 50 50 mixtures with other compounds. Although all additives decreased somewhat the rate of 1-decene hydroformylation, the order of this inhibitory effect was 1,3,5-trimethylbenzene < cumene < undecanoic acid, which corresponds to the order of the increasing stability of the inclusion complexes of additives with p-CD, at least for 1,3,5-trimethylbenzene (60 M ) and cumene (1200 M ). These results clearly show the possible effect of competition of the various components in the reaction mixture for the cyclodextrin. 

Since the discovery and development of highly efficient Rh catalysts with chiral diphosphites and phosphine-phosphites in the 1990s, the enantioselectivity of asymmetric hydroformylation has reached the equivalent level to that of asymmetric hydrogenation for several substrates. Nevertheless, there still exist substrates that require even further development of more efficient chiral ligands, catalyst systems, and reaction conditions. Diastereoselective hydroformylation is expected to find many applications in the total synthesis of complex natural products as well as the syntheses of biologically active compounds of medicinal and agrochemical interests in the near future. Advances in asymmetric hydrocarboxylation has been much slower than that of asymmetric hydroformylation in spite of its high potential in the syntheses of fine chemicals. 

Gonsidering that the chiral aldehydes obtained by asymmetric hydroformylation of vinylarenes are often oxidized to give the corresponding acids that exhibit biological activities, asymmetric hydrocarboxylation and its related reactions naturally attract much attention. Unfortunately, however, less successful work has not been reported on this subject than on the hydroformylation. Palladium(ii) is most commonly used for this purpose. Styrene and other vinylaromatics are most widely examined and the data for representative examples are summarized in Table 14. The products are of... 

Metal-catalysed hydrocarboxylation of olefins (Equation 3) is the poor relative of the more famous hydroformylation. It generally requires forcing reaction conditions and suffers from mediocre activities and selectivities (n/i ratio). Moreover, the same products can be made via hydroformylation and oxidation of the aldehyde product.431 Consequently, there are few industrial applications of hydrocarboxylation e.g. Ni(CO)4-catalysed production of propionic acid by hydrocarboxylation of ethylene.432,433... 

Advance in asymmetric hydrocarboxylation has been much slower than that of asymmetric hydroformylation in spite of its high potential in the syntheses of fine chemicals. However, some very encouraging results have recently been reported, and thus much improvements in this reaction can be expected in the next decade. 

Substrate Hydroformylation RhH(CO) (PPh3)3 Hydroformylation [(—)-DIOP] PtCl2/SnCl2 Hydrocarboxylation PdCl2 ... 

Other approaches that have been suggested include catalytic asymmetric hydroformylation of 2-methoxy-6-vinylnaphthalene (6) using a rhodium catalyst on BINAPHOS ligand followed by oxidation of the resultant aldehyde 7 to yield 5-naproxen (Scheme 6.3).22 However, the tendency of the aldehyde to racemize and the co-generation of the linear aldehyde isomer make the process less attractive. Other modifications related to this process include catalytic asymmetric hydroesterification,23 hydrocarboxylation,24 and hydrocyanation.25... 

The HCo(CO)4-catalyzed hydrocarboxylation of alkenes has also been known for a long time. The mechanism is analogous to that presented for hydroformyla-tion (Scheme 1), except that H2O is used instead of H2. Hydrocarboxylation is generally slower than hydro-formylation, and it is believed that the concentrations of the intermediate species are quite low relative to those seen for hydroformylation. Pyridine has a rateenhancing effect that is believed to be due to the facile cleavage of the (acyl)Co(CO)4 intermediate. This reaction forms [pyridine-acyl] + [Co(CO)4] , which is more rapidly hydrolyzed by water to form the product carboxylic acid and HCo(CO)4. 

The hydrocarboxylation reactions discussed above have been proposed to involve direct addition of water to the metal center prior to elimination of the product, analogous to the oxidative addition of hydrogen to a metal center at the end of a hydroformylation catalytic cycle. Another class of hydrocarboxylation reactions is more analogous to the haUde-promoted Monsanto acetic acid process, where one has a reductive elimination of an acyl halide species that is rapidly hydrolyzed with free water to generate the carboxylic acid and HX. 

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