N,N-bis-2,2,6,6-tetra:methyl-4- piperidyl-alkane-di:amine(s) - prepd. by dissolving crude amine in ketone solvent and crystallising soln., for pure polymer light stabilisers

摘要

Prodn. comprises dissolving crude (I) in a 3-9C ketone solvent (II) and crystallising the soln. n = 2-10. Also pure (I), with purity of at least 98 wt.%, contains not above 150 ppm 2,2,6,6-tetra methyl-4-piperidone (III) and with initial APHA value not above 30. Pref. (II) is acetone, MEK, diethylketone, MIBK or di-isobutyl ketone, pref. acetone; crude (I) is obtd. by hydrogenation of (III) and an alkane-diamine (IV); crude (I) is dissolved in 50-200 wt.% (II) (w.r.t. wt. of I) at 40-60 deg. C, and the soln. is crystallised by cooling to 0-10 deg. C; pref. pure (I) contains not above 120 ppm (III) and has APHA values = not above 20 (as made) and not above (100 (after 3 months at 60 deg. C); pure (I) with n = 6 is pref. USE/ADVANTAGE - Simple, mild process gives a pure prod. with low susceptibility to discolouration (due to the low content of (III)). (6pp Dwg.No 0/0)