Monsanto process

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The Monsanto process is an industrial method for the manufacture of acetic acid by catalytic carbonylation of methanol.[1] The Monsanto process has largely been supplanted by the Cativa process, a similar iridium-based process developed by BP Chemicals Ltd, which is more economical and environmentally friendly.

This process operates at a

Monsanto Company in 1966, which introduced a new catalyst system.[2]

Catalytic cycle

The catalytic cycle of the Monsanto process
The catalytic cycle of the Monsanto process

The

methyl iodide and the hydrolysis of the acetyl iodide to acetic acid and hydrogen iodide.[4]

The reaction has been shown to be

first-order with respect to methyl iodide and [Rh(CO)2I2]−. Hence the oxidative addition of methyl iodide is proposed as the rate-determining step
.

Tennessee Eastman acetic anhydride process

Acetic anhydride is produced by carbonylation of methyl acetate in a process that is similar to the Monsanto acetic acid synthesis. Methyl acetate is used in place of methanol as a source of methyl iodide.[5]

CH3CO2CH3 + CO → (CH3CO)2O

In this process lithium iodide converts methyl acetate to lithium acetate and methyl iodide, which in turn affords, through carbonylation, acetyl iodide. Acetyl iodide reacts with acetate salts or acetic acid to give the anhydride. Rhodium iodides and lithium salts are employed as catalysts. Because acetic anhydride hydrolyzes, the conversion is conducted under anhydrous conditions in contrast to the Monsanto acetic acid synthesis.

References

  1. doi:10.1002/14356007.a01_045
    .
  2. ^ "Production method: The Monsanto process". www.greener-industry.org.uk. Archived from the original on 2014-08-11. Retrieved 2014-08-27.{{cite web}}: CS1 maint: unfit URL (link)
  3. ISBN 189138953X
  4. Platinum Metals Rev.
    44 (3): 94–105.
  5. doi:10.1016/0920-5861(92)80188-S
    .

External links
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