73440-20-7Relevant academic research and scientific papers
Comparative Study of lactide polymerization with lithium, sodium, magnesium, and calcium complexes of BHT
Chen, Hsuan-Ying,Mialon, Laurent,Abboud, Khalil A.,Miller, Stephen A.
, p. 5252 - 5261,10 (2012)
A series of Li, Na, Mg, and Ca complexes with 2,6-di-tert-butyl-4- methylphenol (BHT) as the ligand has been synthesized, and their reactivity for the ring-opening polymerization of lactide has been studied. The Ca complex with 2,2′-ethylidenebis(4,6-di-tert-butylphenol) (EDBP) as the ligand also has been synthesized to compare with the BHT systems. All complexes, in the presence of benzyl alcohol as initiator, exhibit high activity for the ring-opening polymerization of lactide. Polymerization activities follow the order of Na ? Li > Ca ? Mg. Additionally, metal-BHT systems are more efficient than metal-EDBP systems, and this superiority was pronounced in THF solution. Four model metal-BHT complexes with coordinated dimethoxyethane (DME) have been characterized by single-crystal X-ray diffraction. These complexes exhibited a wide variation in the Cipso-O-metal angle (159.3° to 180.0°), and DFT calculations suggested that this flexibility allows the metal to vary its electron density and thereby expedite the catalytic cycle that requires both monomer activation and substrate lability.
