In the course of oxidation, reaction temperature should rise step by step, and in the late stage, reduced pressure distillation should follow so that the concertration of glyoxalic acid can rise and production rate of allantoin can rise up to 40%.

• 在氧化反应的过程中逐步地提高反应温度，反应后期进行减压浓缩，提高了乙醛酸的浓度，缩短了氧化时间，并使尿囊素产率达到40%25。