1- Alkenes homogeneous catalysis

Khan, M. M. T. 1974, Homogeneous Catalysis by Metal Complexes, Vol. II, Activation of Alkenes and Alkynes, Academic Press New York - London... 

Regioselective reactions belong to the most important applications of homogeneous catalysis. An example is the hydroformylation of alkenes, which is a very important industrial reaction ... 

The hydroformylation of alkenes, which was originally discovered by Otto Roelen in 1938 [1], has developed into one of the most important applications of homogeneous catalysis in industry (Scheme 1) [2,3]. Today, more than 9 million tons of so-called oxo-products are produced per year, a number which is still rising continuously. The majority of these oxo-products stem... 

As with carboxylic acids obtained by palladium hydroxycarbonylation, their derivatives esters, amides, anhydrides and acyl halides are synthesized from alkenes, CO and HX (X = OR, NR2 etc.). The Pd-catalyzed methoxycarbonylation is one of the most studied reactions among this type of catalyzed carbonylations and has been reviewed and included in reports of homogeneous catalysis.625, 26 The methoxycarbonylation has been applied to many different substrates to obtain intermediates in organic syntheses as well as specific products. For instance, the reaction has been applied for methoxycarbonylation of alkynes666 Highly efficient homogeneous Pd cationic catalysts have been reported and the methoxycarbonylation of alkynes has been used to develop economically attractive and environmentally benign process for the production of methyl... 

Based on these observations and several other experimental results with cofeeding of ethene and 1-alkene,9 the selectivity of branched hydrocarbons,11 and the different promoter effects of Li-, Na-, K-, and Cs-carbonate/oxide,1213 a novel mechanism has been proposed that is consistent with these various experimental results.14 The formulation of this mechanism follows the knowledge of analogous reactions in homogeneous catalysis and gives a detailed insight in the crucial step of C-C linkage formation. The aim of this work is to discuss in detail these experiments and their relationship to the proposed mechanism. 

The reaction between alkenes and synthesis gas (syngas), an equimolar mixture of carbon monoxide and hydrogen, to form aldehydes was discovered in 1938 by Otto Roelen [1,2]. Originally called oxo-reaction , hydroformyla-tion is the term used today. This reflects the formal addition of formaldehyde to the olefinic double bond. Commercially, homogeneous metal complexes based on cobalt and rhodium are used as catalysts. With more than 10 million metric tons of oxo products per year, this reaction represents the most important use of homogeneous catalysis in the chemical industry. 

Insertion of carbon monoxide and alkenes into metal-carbon bonds is one of the most important reaction steps in homogeneous catalysis. It has been found for insertion processes of platinum [16] that the relative positions of the hydrocarbyl group and the unsaturated fragment must be cis in the reacting complex [17], The second issue concerns the stereochemical course of the reaction, insertion versus migration as discussed in Chapter 2.2. 

Scheme 7.7 Mechanism of homogenous catalysis of alkene hydrosilylation by [ Rh( i-OSiMe3)(cod) 2].

Breit, B. and Seiche. W. (2003) Hydrogen bonding as a constniction element for bidentate donor ligands in homogeneous catalysis Regioselective hydroformylation of terminal alkenes, J.Ahi. Chem. Soc.. 125. 6608-6609. 

---