Wu, Jing published the artcileElectronic and steric effects of substituents in series of Zn2+ asymmetrical bis-Schiff-base ligands complexes on catalytic ring-opening copolymerization of CHO and MA, SDS of cas: 4551-69-3, the publication is Journal of Organometallic Chemistry (2014), 302-311, database is CAplus.
Based on the half-unit Schiff-base ligand HL and series of asym. bis-Schiff-base ligand H2Ln (n = 1-6) in situ synthesized from the reaction of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), o-phenylenediamine, and/or different salicylaldehyde derivatives, complexes [Zn(L)2] (1) and series of [Zn(Ln)] (n = 1-6, 2-7) are obtained, resp. Complex 1 proves to be inactive, resulting from its saturated octahedral coordination environment around the central Zn2+ ion, while in complexes 2-7, the unsaturated coordination environment for the catalytic active centers (Zn2+ ions) permits the monomer insertion for the effective bulk or solution copolymerization of CHO (cyclohexene oxide) and MA (maleic anhydride). As to the electron and steric effect in complexes 2-7 on the catalytic behaviors, the copolymerization results show that the introduction of withdrawing -Br substituent para to the phenoxide group endows higher reactive activity, while the bulkiness effect of the encumbering substituent (-Br, -OMe or tert-butyl) ortho to the phenoxide groups is in favor of the chain growth of the copolymers. Moreover, all the bulk copolymerizations in 2-7/DMAP (4-(dimethylamino)pyridine) systems afford poly(ester-co-ether)s, while lower catalyst and co-catalyst concentration for 3/DMAP system is helpful for the formation of perfectly alternating polyester in solution Of the three co-catalysts, DMAP is found to be the most efficient, while an excess thereof is detrimental for the chain growth of the copolymers.
Journal of Organometallic Chemistry published new progress about 4551-69-3. 4551-69-3 belongs to pyrazoles-derivatives, auxiliary class Benzenes, name is 4-Benzoyl-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, and the molecular formula is C17H14N2O2, SDS of cas: 4551-69-3.
Referemce:
https://en.wikipedia.org/wiki/Pyrazole,
Pyrazoles – an overview | ScienceDirect Topics