Process for eliminating interfering by-products in the direct oxidative esterification of methacrolein

A process for preparing alkyl methacrylates, comprising:

• a) preparing methacrolein in a reactor I,
• b) oxidatively esterifying the methacrolein in the presence of an alcohol, oxygen, and a heterogeneous noble metal-containing catalyst in at least one reactor II,
• c) distilling a reactor output from the at least one reactor II in a distillation column I for separation of the methacrolein and portions of the methanol,
• d) optionally, pretreating a bottom output from c), comprising
• i) adding an acid to change a pH of the bottom output,
• ii) adding water to obtain a biphasic mixture, and
• iii) reactively treating at least a portion of the biphasic mixture from ii), and
• e) extracting the bottom output from distillation column I from c) or an organic phase of the bottom output from distillation column I from d), in an extraction I,
• wherein an amount of the methacrolein in the organic phase from extraction I is greater than that in the bottom output from distillation column I, and
• wherein there is produced an alkyl methacrylate composition comprising methacrolein dimethyl acetal (DMIB), and which has a DMIB content of less than 90 ppm.