Method for producing α-hydroxyisobutyric acid amide and reactor

A reaction apparatus for producing α-hydroxyisobutyric acid amide by hydration of acetone cyanohydrin in the presence of a catalyst composed mainly of manganese oxide, the reaction apparatus comprising:

• a first reaction region comprising a region (I) and a region (II);
• a second reaction region connected in series to the first reaction region;
• a third reaction region connected in series to the second reaction region;
• a piping configured to supply a reaction raw material liquid containing the acetone cyanohydrin dividedly to the first reaction region and at least the second reaction region;
• a piping configured to cyclically supply a portion of a reaction liquid withdrawn from the region (II) of the first reaction region back to the region (I) of the first reaction region, and a portion of a reaction liquid withdrawn from the region (II) of the first reaction region back to the region (II) of the first reaction region;
• a piping configured to supply an oxidizing agent to at least one of the first reaction region, the second reaction region, and the third reaction region;
• and
• an outlet;
• wherein the third reaction region:
• is closer to the outlet than the first and second reaction regions, and
• is configured to treat the reaction liquid by single pass flow without recirculation.