| 摘要 |
Novel compounds have been discovered in which a bis compound of a polysubstituted 2-keto-1,4-diazacycloalkane ("2KDZC") provides a bridge between diisocyanate groups so as to form an oligomeric 2KDZC-urethane ("2K-U" oligomer) having from 2 to about 15 repeating units. The bis compound bridge itself consists essentially of two distally linked polysubstituted 2KDZC moieties, and the 2K-U oligomer formed consists essentially of two 2KDZC moieties linked through their N1 atoms, which moieties in turn are distally linked to urethane groups through the N4 atoms of the 2KDZC. Such 2K-U oligomers unexpectedly contain a self-limiting number of 2K-U repeating units which happens to provide 2K-U oligomers which are desirable and highly effective u-v light stabilizers in organic materials. More specifically, this invention provides a novel class of polymeric hindered amine-urethane derivatives, particularly piperazinone bis compounds which may be distally linked to each other in a single step reaction utilizing an appropriately substituted diamine, a haloform such as bromoform or chloroform, in one of several known syntheses for making 2-keto-diazacycloalkanones, some of which syntheses may preferably utilize a phase transfer catalyst. This bis compound may then be hydroxyalkylated and reacted with an appropriate diisocyanate.
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