METHODS OF USING N-OXYL POLYMERIZATION INHIBITOR IN A WASH SETTLER FOR PREPARING METHYL METHACRYLATE

The present invention provides methods comprising washing or, preferably, washing and neutralizing a sulfur acid containing crude MMA stream to generate a two phase stream containing at least methacrylic acid, methacrylamide (MAM), water and methanol, and an organic component containing methyl methacrylate and thereby form an aqueous component; including in any of the organic component, the aqueous component of a neutralized sulfur acid containing crude methyl methacrylate (MMA) stream or the organic component of a neutralized sulfur acid containing crude methyl methacrylate (MMA) stream one or more N-oxyl compound polymerization inhibitor; followed by separating the aqueous component from the organic component, thereby forming a treated crude MMA stream and an aqueous stream to remove residual (meth) acrylic acid.