title: Synthesis and characterization of multi-alkali-metal tetraphenolates and application in ring-opening polymerization of lactide.
abstract: A series of alkali metal complexes supported by two bulky tetraphenols were synthesized and characterized. The reactions of α,α,α',α'-tetra(3,5-di-tert-butyl-2-hydroxyphenyl)-p-xylene(para-tetraphenol) with (n)BuLi, sodium, and KSi(NMe(2))(3) gave bimetallic complexes 1, 2, and 3, respectively. Treatments of the α,α,α',α'-tetra(3,5-di-tert-butyl-2-hydroxyphenyl)-m-xylene(meta-tetraphenol) with 2 or 4 equiv of (n)BuLi afforded complexes 4 or 5, while the reactions of meta-tetraphenol with sodium and KSi(NMe(2))(3) gave only trimetallic complexes 6 and 7 for the additional p-π interaction. Complexes 1-7 were all characterized by single-crystal X-ray diffraction techniques. In the presence of benzyl alcohol, all complexes are active catalysts for the ring-opening polymerization of L-lactide. Comparatively, bimetallic complexes 1, 2, and 3 are more efficient catalysts because of their symmetric structures, in which complex 3 presents as a rare highly active potassium catalyst for the ring-opening polymerization of lactide, leading to polymers with good molecular weight control and narrow molecular weight distributions.
authors.affiliation: Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China.
authors.forename: Jinjin
authors.initials: J
authors.lastname: Zhang
authors.forename: Chunli
authors.initials: C
authors.lastname: Jian
authors.forename: Yuan
authors.initials: Y
authors.lastname: Gao
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: Tang
authors.forename: Jincai
authors.initials: J
authors.lastname: Wu
mesh_terms: D019905:Benzyl Alcohol / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D004146:Dioxanes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008672:Metals, Alkali / Q000737:chemistry*; D015394:Molecular Structure; D019800:Phenol / Q000138:chemical synthesis / Q000737:chemistry*; D058105:Polymerization; D014961:X-Ray Diffraction
chemical_list: D056831:Coordination Complexes; D004146:Dioxanes; D008672:Metals, Alkali; D019800:Phenol; C091880:dilactide; D019905:Benzyl Alcohol