Purification process for methyl acetate
AssigneeHoechst Celanese Corporation
InventorsMark O. Scates, Russell K. Gibbs, Jr., G. Paull Torrence
Life of this patent
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Abstract
Esters such as methyl acetate which contain carbonyl impurities including aldehydes are purified by adding to the esters an amino compound which reacts with the carbonyls to form water soluble nitrogenous derivatives, separating an organic ester phase from an aqueous derivative phase, and distilling the ester phase to further remove heavier impurities. The formation of nitrile from the nitrogenous derivative is minimized by adding water to the distillation column or washing the aqueous bottoms from distillation with water to further remove the derivatives from any ester contained in the bottoms. The organic phase recovered from the bottoms can be recycled to the distillation to recover ester.
Claims10
In a process for carbonylating methyl acetate to acetic anhydride, acetic acid or to coproduce acetic acid and acetic anhydride in the presence of a Group VIII metal carbonylation catalyst, the improvement which comprises:
- using as said methyl acetate a methyl acetate stream which contains carbonyl impurities and has been purified prior to carbonylation to remove said carbonyl impurities by contacting said methyl acetate with an aqueous solution of an amino compound under conditions at which said amino compound reacts with said carbonyl impurities for conversion to water soluble nitrogenous derivatives of said carbonyls, forming two separate phases comprising an organic phase containing a major portion of said methyl acetate and an aqueous phase containing said nitrogenous derivatives, distilling said organic phase and recovering a purified methyl acetate distillate stream for use in said carbonylation.
Dependencies are inferred from the claim text.