ROELEN Carbonylation

ROBINSON - FOULDS Quinoline synthesis 322 ROBINSON - GABRIEL Oxazole synthesis 323 ROELEN Carbonylation 323 ROSENMUND - von BRAUN Aromatic cyanation 324... 

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). 

It was discovered by Roelen in 1938 and is the oldest and largest volume catalytic reaction of alkenes, with the conversion of propylene to butyraldehyde being the mosi important. About 5 million tons of aldehydes and aldehyde derivatives (mostly alcohols) are produced annually making the process the most important industrial synthesis using a metal carbonyl complex as a catalyst. The name hydroformylation arises from the fact that in a formal sense a hydrogen atom and. formyl group are added across a double bond. The net result of the process is extension of (he carbon chain by one and introduction of oxygen into the molecule. 

Metal-catalyzed reactions of CO with organic molecules have been under investigation since the late 1930s and early 1940s, when Roelen (/) discovered the hydroformylation reaction and Reppe (2) the acrylic acid synthesis and other related carbonylation reactions. These early studies of the carbonyla-tions of unsaturated hydrocarbons led to extremely useful syntheses of a variety of oxygenated products. Some of the reactions, however, suffered from the serious problem that they produced isomeric mixtures of products. For example, the cobalt-catalyzed hydroformylation of propylene gave mixtures of n-butyraldehyde and isobutyraldehyde. 

Since its discovery some 50 years ago by Roelen, a great deal of research has been carried out on the reaction and its industrial importance is great. The initial work used as catalyst precursor [Co2(CO)8] or simple cobalt salts which were carbonylated under the reaction conditions. Subsequently, phosphine-modified cobalt catalysts were introduced and, more recently, rhodium and platinum catalysts. Only the cobalt and rhodium catalysts have found industrial use to date. 

Otto Roelen and Walter Reppe Industrial Applications of Metal Carbonyls... 

The hydroformylation reaction was discovered in 1938 by Otto Roelen in the Ruhrchemie laboratories at Oberhausen (Germany) [1, 2], Since that day, hydroformylation has become a widely studied and interesting reaction for both academic and industrial researchers. This reaction consists formally in the transformation of olefins under carbon monoxide and hydrogen pressure leading to linear and branched aldehydes as primary products (see Section 2.4.1.1). The interest of such a reaction resides in the formation from an olefin of a new carbon-carbon bond with the introduction of a carbonyl function which can be easily transformed into different products of industrial interest like detergents, plasticizers, and pharmaceutical products. The overall production capacity of oxo products was estimated to be aroimd 10 million tons per year in 2001 and this production is still increasing. 

Reppe was told about Otto Roelen s 0X0 process by Ruhrchemie in the spring of 1940, which gave him the idea that the carbonylation reaction could be extended to ethylene. 

As early as 1938, Otto Roelen discovered hydroformylation when observing the formation of aldehydes in the presence of cobalt carbonyls. Cobalt carbonyls are extremely effective catalysts for a variety of carbonylation reactions, but have been largely overlooked in recent years due to the overwhelming research efforts into rhodium and iridium chemistry. However, cobalt affords a much cheaper catalyst and is still attractive from an industrial perspective. HP-NMR and HP-IR studies of such catalysts have recently been reviewed. 

Hydroformylation (Oxo-process, O. Roelen, Ruhrchemie, 1938 worldwide there are three variants of the Oxo-process 1. the classical synthesis using HCo(CO)4 as catalyst 2. Shell s SHOP-process, based on a cobalt carbonyl - phosphine complex 3. UCC s process, using a rhodium catalyst). ... 

It is generally agreed that Roelen s discovery of the hydroformylation reactiont was the birth of the transition metal-catalyzed carbonylation. Initially, Co catalysts were most extensively used, but the Rh-based processes have since been developed as a superior methods. Although Pd may have been tested along with several other metals, such as Fe, Ru, and Ni, it has never been shown to be very useful in the hydroformylation reaction, sometimes called the oxo process. A publication in 1963 by Tsuji et al. on a related but clearly different reaction of alkenes with CO and alcohols in the presence of a Pd catalyst producing esters was one of the earliesL if not the earliesL reports describing a successful and potentially useful Pd-catalyzed carbonylation reaction. This was soon followed by the discovery of another Pd-catalyzed carbonylation reaction of allylic electrophiles with CO and alcohols ° (Scheme 7). 

The hydroformylation reaction which was found by O. Roelen and the carbonylation found by W. Reppe fall into the class of three-component reactions. 

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