Carbonylation of olefins

The addition of alcohols to form the 3-alkoxypropionates is readily carried out with strongly basic catalyst (25). If the alcohol groups are different, ester interchange gives a mixture of products. Anionic polymerization to oligomeric acrylate esters can be obtained with appropriate control of reaction conditions. The 3-aIkoxypropionates can be cleaved in the presence of acid catalysts to generate acrylates (26). Development of transition-metal catalysts for carbonylation of olefins provides routes to both 3-aIkoxypropionates and 3-acryl-oxypropionates (27,28). Hence these are potential intermediates to acrylates from ethylene and carbon monoxide. 

Garbonylation of Olefins. The carbonylation of olefins is a process of immense industrial importance. The process includes hydroformylation and hydrosdylation of an olefin. The hydroformylation reaction, or oxo process (qv), leads to the formation of aldehydes (qv) from olefins, carbon monoxide, hydrogen, and a transition-metal carbonyl. The hydro sdylation reaction involves addition of a sdane to an olefin (126,127). One of the most important processes in the carbonylation of olefins uses Co2(CO)g or its derivatives with phosphoms ligands as a catalyst. Propionaldehyde (128) and butyraldehyde (qv) (129) are synthesized industrially according to the following equation ... 

Hydro carbonylation of olefins, hydroformylation, hydroesterification and hy-droxycarbonylation are reactions which appear to be of particular interest. Indeed, they allow the simultaneous creation of a new C - C bond as well as the introduction of a functional group (aldehyde, ester and acids). One or two new stereogenic centres can thus be formed at the same time (Scheme 26). Despite the difficulty of using high carbon monoxide pressure, the aheady existing industrial processes prove that such reactions can be performed on a very large scale [107]. 

The Pd(II)-catalysed asymmetric carbonylation of olefins with a chiral thiourea as the hgand has been reported recently. Since these ligands are stable in the presence of oxidising agents, they prevent Pd precipitation and double-bond isomerisation (Scheme 35) [141]. 

Rhodium catalyzed carbonylations of olefins and methanol can be operated in the absence of an alkyl iodide or hydrogen iodide if the carbonylation is operated in the presence of iodide-based ionic liquids. In this chapter, we will describe the historical development of these non-alkyl halide containing processes beginning with the carbonylation of ethylene to propionic acid in which the omission of alkyl hahde led to an improvement in the selectivity. We will further describe extension of the nonalkyl halide based carbonylation to the carbonylation of MeOH (producing acetic acid) in both a batch and continuous mode of operation. In the continuous mode, the best ionic liquids for carbonylation of MeOH were based on pyridinium and polyalkylated pyridinium iodide derivatives. Removing the highly toxic alkyl halide represents safer, potentially lower cost, process with less complex product purification. 

Though important results have already been obtained in the carbonylation of olefins, the field still remains open. Development of more active, efficient and stable catalysts based also on less expensive metals will make the carbonylation processes more attractive. Carbonylation of less common olefins, including functionalised ones, has to be explored in more depth. Other important targets are the efficient living copolymerisation, the multiple olefin insertion producing non-alternating copolymers and the selective synthesis of unsaturated products like acrylates and methacrylates. 

Acknowledgements The authors are indebted to the undergraduate and graduate students we collaborated with, in particular to Federico Dall Acqua who is at the beginning of his doctoral studies on the field of carbonylation of olefins and which helped us in the preparation of the manuscript. 

Carbonylation of olefins produces aldehydes that are converted to other deriv-... 

Carbonylations of olefins, acetylenes, halides, alcohols, amines, nitro compounds, etc., promoted by transition metal complexes are very important in both industrial and laboratory organic syntheses. The mechanisms of those reactions have been studied extensively, especially for those associated with commercial processes. " The research... 

The absence of free isomerized olefins, the Constance of isomeric composition of the products throughout the whole reaction in hydro-formylation experiments of 1-pentene and 4-methyl-1-pentene under high carbon monoxide pressure, the distribution of deuterium in the hydro-formylation products of 3-methyl-l-hexene-3-di and 3-(methyl-d3)-l-butene-4-d3, and the results of carbonylation of olefins containing a quaternary carbon atom indicate initial formation of an olefin-cobaltcarbonyl complex. Isomerization of this complex, resulting in 1,2 hydrogen shifts in its organic moiety, can produce the necessary precursors of the various aldehydes that are formed. 

In the gold-catalyzed carbonylation of olefins according to Xu et al., gold(I) carbonyl complexes are considered as active catalysts this reaction proceeds already at room temperature in concentrated sulfuric acid at a CO pressure of 1 atm and leads after acid-catalyzed skeletal rearrangement to tertiary carboxylic acids such as 16,18, and 19 (Scheme 4) [11],... 

Examples of gold-catalyzed carbonylation of amines and olefins exist related to the activation of carbonyl. The first case involves the formation of carbamates from anilines and CO in the presence of alcohols or the production of acetamides from aliphatic amines. In these examples, Au(I) (usually [AuCl(PPh3)]) catalysts are preferred. For the carbonylation of olefins, gold(I) carbonyls are prepared in situ in sulfiu ic acid media to afford carboxyhc acids. ... 

K. Bittler, N. von Kutepovv, D. Neubauer, and H. Reis Angew. Chem. 80, 352 (1968) Angew. Chem. Int. Ed. Engl. 7, 329 (1968) Carbonylation of olefins under mild temperature conditions in the presence of palladium complexes 7 (21) ... 

XXXI. Carbonylation of Olefins and Decarbonylation of Acyl Halides and Aldehydes... 

Olefins are usually carbonylated in the presence of metal carbonyls, such as nickel, cobalt, and iron carbonyls under homogeneous conditions, and the mechanism of these carbonylations has been established in several cases. On the other hand, isolation or formation of true palladium carbonyl has not been reported. Since palladium is an efficient and versatile catalyst for various types of the carbonylation mentioned above, the mechanisms of the carbonylation of olefin-palladium chloride complexes and of metallic palladium catalyzed carbonylations seem to be worth investigating. 

The following mechanism was proposed for the carbonylation of olefin-palladium chloride complex (10). The first step is coordination of carbon monoxide to the complex. Insertion of the coordinated olefin into the palladium-chlorine bond then forms a -chloroalkylpalladium complex (IV). This complex undergoes carbon monoxide insertion to form an acylpalladium complex (V), as has been assumed for many metal carbonyl-catalyzed carbonylation reactions. The final step is formation of a )8-chloroacyl chloride and zero-valent palladium by combination of the acyl group with the coordinated chlorine. 

In the metallic palladium-catalyzed carbonylation of olefins, some hydrogen sources are essential hydrogen halide and molecular hydrogen were found to be the most eflFective. The following sequence of reactions was proposed for the reaction mechanism of the ester and aldehyde formation catalyzed by palladium (23). The first step of the metallic palladium-catalyzed carbonylation seems to be the formation of a palladium-hydrogen bond by the oxidative addition of hydrogen chloride... 

Thus, it was established that metallic palladium catalyzes both carbonylation of olefins to acyl halides or aldehydes in the presence of... 

In early patents by Halcon, molybdenum carbonyls are claimed to be active catalysts in the presence of nickel and iodide [23]. Iridium complexes are also reported to be active in the carbonylation of olefins, in the presence of other halogen [24] or other promoting co-catalysts such as phosphines, arsines, and stibines [25]. The formation of diethyl ketone and polyketones is frequently observed. Iridium catalysts are in general less active than comparable rhodium systems. Since the water-gas shift reaction becomes dominant at higher temperatures, attempts to compensate for the lack of activity by increasing the reaction temperature have been unsuccessful. 

The use of palladium and ruthenium as halogen-free carbonylation catalysts has been studied intensively by Shell. The catalysts were principally designed for the carbonylation of olefins in the presence of alcohols in order to yield carboxylic esters [26], but work also well for the synthesis of carboxylic acids or anhydrides. The latter are formed when the reaction is conducted in an acid as a solvent [27]. The palladium systems typically consist of palladium acetate, tertiary phosphines, and strong acids such as mineral acids or acids with weak or noncoordinating anions such as p-toluenesulfonic acid. Remarkable activities are achieved when aromatic phosphines that carry pyridines as substituents are... 

In the cobalt-catalyzed photochemical carbonylation of olefins, hydroformyla-tion can be performed easily at ambient temperature (and high pressure) with high primary aldehyde selectivities (cf. Section 2.1.1) [59]. Under comparable conditions allylic amines are carbonylated to 2-pyrrolidinone, Al,/V -diallylurea, and A -allyl-3-butenamide [60]. Photochemical methoxycarbonylation of olefins is possible at ambient conditions, i.e., at room temperature and atmospheric pressure [61]. 

Tsuji, J., Ohno, K. Organic syntheses by means of noble metal compounds. XXXI. Carbonylation of olefins and decarbonylation of acyl halides and aldehydes. Advances in Chemistry Series 1968, No. 70, 155-167. 

Garwood (153) has reported the use of a number of crystalline aluminosilicates as catalysts for the carbonylation of olefins to form aldehydes. In a typical run, H-mordenite (50 gm), propylene (1.5 mole), CO (1.1 mole), and Ha (1.1 mole) were charged (in the order stated) to a glass-lined stainless steel autoclave and shaken for 21-24 hours at the conditions shown ... 

Carbonylation of olefins and aryl halides to the corresponding esters or amides find in ILs an ideal media for the palladium-catalysed process. 

Carbonylation of olefins in the presence of alcohols to give esters is called hydroesterification. Similarly, olefin carbonylation in the presence of carboxylic acids yields acid anhydrides. Both hydroesterification and acid anhydride formation by olefin carbonylation are covered in section 14.6.4. Other carbonylation variations, including the use of acetylenic substrates, thiols and amines as hydrogen sources and the carbonylation of allylic halides are not discussed. Several excellent reviews of hydrocarboxyiation and carbonylation of olefinshave appeared. 

Anhydrides are produced by the carbonylation of olefins when carried out in the presence of carboxylic acids. For example, Pd acetate, 2-pyridyldiphenylphosphine and p-toluenesulfonic acid in the ratio 0.1 3 5 in a propionic anhydride solvent containing propionic acid (50 mL and 10 mL, respectively), when treated with ethylene (2 MPa) and CO (3 MPa) at 105°C for 1 hr produces 1340 moles of propionic anhydride per mole of Pd per hr with 76% propionic acid conversion . ... 

Bis(9-borabicyclo [3.3.1]nonane) is a useful reagent for synthesis of aldehydes by carbonylation of olefins.17... 

Several mechanisms for homogeneous catalytic reactions by transition metal complexes could be even more complicated and consist of more than four steps. Carbonylation of olefins (Figure 5.16) and olefins methathesis over a complex catalysts WC16 + EtAICk, Mo(CO)e/Si02 where n is the oxidation state of Mol,+ Wn+ and n=2-4 (Figure 5.17), can be described by catalytic cycles with 6 intermediates. 

Reppe reactions are the formation of carboxylic acids from olefins by reaction with carbon monoxide and water utilizing a metal carbonyl catalyst. The same reactants combine to form carboxylic acids in the presence of an acid catalyst. These acid catalyzed reactions are known as Koch Carbonyla-tion reactions. Commercial processes utilizing this route are the DuPont process for glycolic acid from carbon monoxide and formaldehyde and the carbonylation of olefins to neo acids practiced by Exxon and Shell. 

---