| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a purification method performed under specific conditions which, when purifying N-tert-butylacrylamide (TBAM) by a sublimation method, can provide TBAM of high purity with little impurity contained in TBAM after purification and little coloration.SOLUTION: The purification method of TBAM comprises: separating from a reaction mixture 2-acrylamido-2-propanesulfonic acid obtained by reacting acrylonitrile, sulfuric acid, and isobutylene; recovering byproduct TBAM contained in the reaction mixture after the separation as crude crystals; and thereafter subliming the crude crystals from a molten liquid of 135 to 160°C under 600 Torr or less, and cooling the sublimation gas in stages in the order of 130 to 150°C at the outlet of a melting tank, 80 to 100°C at an upper part of a sublimation and collection tower, and 40 to 60°C at a lower part of the sublimation and collection tower. A content of the impurity, 3,3'-iminopropionitrile, in TBAM is 1000 ppm or less.</p> |
