Halcon process

In chemistry, the Halcon process refers to technology for the production of propylene oxide by oxidation of propylene with tert-butyl hydroperoxide. The reaction requires metal catalysts, which typically contain molybdenum:[1]

(CH3)3COOH + CH2=CHCH3 → (CH3)3COH + CH2OCHCH3

The byproduct tert-butanol is recycled or converted to other useful compounds. The process once operated at the scale of >2 billion kg/y.

The lighter analogue of propylene oxide, ethylene oxide, is produced by silver-catalyzed reaction of ethylene with oxygen. Attempts to implement this relatively simple technology to the conversion of propylene to propylene oxide fail. Instead only combustion predominates. The problems are attributed to the sensitivity of allylic C-H bonds.

Mechanism

The oxidation is thought to proceed by formation of Mo(η2-O2-tert-Bu) complexes. The peroxy O center is rendered highly electrophilic, leading to attack on the alkene.[2]

History

The Halcon process was developed by Halcon International.[3]

References
  1. Roger A. Sheldon (1983). "Syntheses and Uses of Hydroperoxides and Dialkylperoxides". In Patai, Saul (ed.). Peroxides. PATAI'S Chemistry of Functional Groups. John Wiley & Sons. doi:10.1002/9780470771730.ch6.
  2. Mimoun, Hubert (1987). "Do metal peroxides as homolytic and heterolytic oxidative reagents. Mechanism of the Halcon Epoxidation Process". Catalysis Today. 1 (3): 281–295. doi:10.1016/0920-5861(87)80012-3.
  3. Fallwell, William (1981). "Ralph Landau wins 1981 Perkin Medal". Chemical & Engineering News Archive. 59 (7): 16. doi:10.1021/cen-v059n007.p016.


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