Monsanto process
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 product. Rhodium iodides and lithium salts are employed as catalysts. Because acetic anhydride is not stable in water, the conversion is conducted under water-free (anhydrous) conditions in contrast to the Monsanto acetic acid synthesis.