(Meth)acrylamide is stabilised against polymerisation by the addn. of 0.001-1.0% of 2-mercaptoimidazoline, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, alkali metal- or ammonium salts of these or derivatives such as low alkyl-substituted derivatives. The inhibitor may be added during the prodn. of (meth)acrylamide by hydrolysis of (meth)acrylonitrile so that it inhibits polymerisation of the (meth)acrylamide during the stages of concentrating the solution, drying and storing the product. In this type of process, 0.001-1.0% nitrosobenzene may also be added to increase the inhibiting action during the solution concentration and crystal separation stages, the advantage being that most of this inhibitor escapes during drying and does not remain behind in the crystals.
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