This document summarizes hydroformylation, an industrially important reaction that uses cobalt or rhodium catalysts to produce aliphatic aldehydes from olefins and synthesis gas. It discusses the uses of aldehydes produced via hydroformylation, the homogeneous transition metal catalysts used, including cobalt tetracarbonyl hydride and tris(triphenylphosphine)rhodium carbonyl hydride, the reaction mechanism, and several industrial processes employing cobalt catalysts, such as the BASF-oxo, Exxon, and Shell processes.

1. Hydroformylation using
Co-catalysts
Nurlybek Amangeldiuly
1st year MS student
Catalytic Methods in Organic Synthesis
Spring’ 2015

2. Contents
• Introduction
• Uses
• Catalysts
• Mechanism
• Industrial processes
• References

3. Introduction
The hydroformylation (a.k.a oxo reaction, or Roelen reaction, 1938) is an
industrially important homogeneously catalyzed reaction of olefins with
synthesis gas for the production of aliphatic aldehydes and is considered one of
the most important developments in industrial chemistry of the 20th century.
As hydroformylation catalysts in the chemical industry the organometallic Co or
Rh are used.

4. Uses
• The initially formed aldehydes are usually hydrogenated to alcohols, which
are used as plasticizers for PVC, SAS for detergents and cleaning agents
and as a solvent or further processed to form polymers.
• Hydroformylation is also used in specialty chemicals, relevant to
the organic synthesis of fragrances and natural products.
• The total capacity of the hydroformylation plants in 2002 was around 10.8
million tonnes per year.

5. Catalysts – homogeneous, transition metal
Cobalt tetracarbonyl
hydride Tris (triphenylphosphine)
rhodium carbonyl hydride
• Union Carbide, 1976.
• PPh3 stabilizes the catalytically active
species and blocks the metal
coordination sphere favoring propene
insertion, which leads to the linear
isomer
• O. Roelen, 1938
• PBu3 ligand has also been used with cobalt, to
increase its reactivity and the selectivity for the
linear aldehyde product.
• With PBu3, however, the cobalt catalyst is so
reactive that it also catalyzes the complete
hydrogenation of the aldehyde to the alcohol.
• Not widely used - Catalyst recycling problems.

6. Mechanism
FYI:
• H and COH are formally added across the double bond; it is therefore referred to as
“hydroformylation”
• About 6 billion kilograms of butanal are produced annually by hydroformylation
and used to obtain plasticisers, solvents and lubricants
N-butyraldehyde: anti-Markovnikov,
major product

7. Mechanism
• By Markovnikov’s rule – Large steric effect due to the size of ligands
• By Anti-Markovnikov’s rule – Less steric effect, hence higher selectivity towards the
linear products

8. Mechanism
Disadvantages:
• Catalyst losses due its high volatility
• Loss of alkene through hydrogenation in a reaction
competing with hydroformylation
• Inherent difficulties in mechanic studies
• R.F. Heck and D.S. Breslow, 1961
1.The catalyst HCo(CO)3 is formed due to CO
dissociation
2.Olefin is added
3. Beta-addition to alkyl complex
4. CO is added
5. CO is inserted between the catalyst and olefin
sides
6. Oxidative H2 addition (irreversible, rate limiting
step)
7. Reductive elimination of the aldehyde

9. Industrial processes that use Co-catalysts
BASF-oxo process
• high pressure and low temperature 300 bar /150-170°C
• Co losses are compensated by addition of Co salts
Exxon process
• Conversion of higher alkenes (C6 – C12) and syngas under normal
hydroformylation conditions
• Co catalyst is not decomposed by oxidation
• 80% yield of butyraldehydes with the ratio of 3/4
Shell process
• Co complexes modified with phosphine ligands
• C7 – C14
• formed aldehydes directly hydrogenated to the alcohols and separated by
distillation to allow the catalyst regeneration
• 40 – 80 bar/150-190°C

10. References
• Elschenbroich C., Salzer A. Organometallics. Weinheim:VCH, 1992
• Astruc Didier. Organometallic Chemistry and Catalysis. Berlin: Springer, 2007
• Lecture notes
• http://en.wikipedia.org/wiki/Hydroformylation
• http://de.wikipedia.org/wiki/Hydroformylierung
• http://en.wikipedia.org/wiki/Butyraldehyde
• http://ethesis.inp-toulouse.fr/archive/00000780/01/sharma.pdf