2- Pyrazolin-5-ones polymeric

This section comprises a few 3-pyrazolin-5-ones which do not fit well in other sections and some polymeric 2-pyrazolin-5-ones. 

Several pyrazolinone polymers have been prepared by linking polymers and pyrazolinones by amide linkages. This has been done by treating copolymers containing maleic anhydride with l-(aminophenyl)-2-pyrazolin-5-ones162,1273 and by treating the acid chloride of l-(3-carboxyphenyl)-3-methyl-2-pyrazolin-5-one with polymeric... 

Lin and co-workers also investigated a related ligand system derived from 4-benzoyl-3-methyl-l-phenyl-2-pyrazolin-5-one (Figure 12). The related magnesium and zinc benzy-loxy-bridged complexes are all active for the controlled polymerization of lactide, with... 

Mw/M 1.07-1.46). In a [ater work, Lin and coworkers elaborated further on these results, and reported two complexes where the more encumbered ligand NNO and NNO (tailored around the use 4-benzoyl-3-methyl-2-pyrazolin-5-one) which presented substantial r-conjugation (Fig. 21) [82]. Whereas [ NNO IMg (OBn)l2 (67) was practically inactive towards LA, [ NNO Mg(OBn)]2 (68) was capable of polymerizing both l- and d,l-LA in a living fashion in THF or dichloromethane. The rate of the reaction was lower than found previously with 66 since 1.6-4 h were necessary for 68 to polymerize 200 equiv of l-LA at 30 °C. More importantly, the ROP of d,l-LA in THF at 0 °C afforded heterotactic-enriched PLA (Fj. up to 0.85). 

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