Optimized process for synthesizing methacrylic acid (maa) and/or alkyl methacrylate by reducing unwanted byproducts

A process for preparing methacrylic acid and/or alkyl methacrylate, the process comprising:

• a. reacting acetone and hydrogen cyanide in the presence of a basic catalyst in a first reaction stage for synthesis of acetone cyanohydrin (ACH), to obtain a first reaction mixture comprising the acetone cyanohydrin (ACH);
• b. working up the first reaction mixture comprising the acetone cyanohydrin (ACH);
• c. reacting the acetone cyanohydrin (ACH) and sulfuric acid in one or more reactors I in a second reaction stage for amidation, at an amidation temperature in the range from 85° C. to 130° C., to obtain a second reaction mixture comprising sulfoxyisobutyramide and methacrylamide;
• d. converting the second reaction mixture by heating to a conversion temperature in the range from 130° C. to 200° C., in one or more reactors II in a third reaction stage for conversion to obtain a third reaction mixture comprising predominantly methacrylamide (MAA) and sulfuric acid;
• e. reacting the third reaction mixture with water and optionally alcohol, in one or more reactors III in a fourth reaction stage for hydrolysis or esterification, to obtain a fourth reaction mixture comprising the methacrylic acid and/or the alkyl methacrylate;
• and
• f. optionally, separating the alkyl methacrylate from the fourth reaction mixture obtained from the fourth reaction stage;
• wherein the sulfuric acid used in the second reaction stage has a concentration in the range from 98.0% by weight to 100.0% by weight;
• wherein a pure ACH mixture which is fed to the second reaction stage has a water content within a range from 0.1 mol % to 10 mol %, based on the ACH present in the pure ACH mixture, and
• wherein a total amount of water used in the second reaction stage is within a range from 0.1 mol % to 20 mol %, based on the ACH present in the pure ACH mixture.