Bimetallic catalyst for synthetizing vertical structure regular makrolon

Abstract

The invention relates to a bimetallic catalyst for synthetizing vertical structure regular makrolon through catalyzing and activating carbon dioxide to be copolymerized with internal compensation alkyleneoxide. The catalyst is a dual four-tooth or dual three-tooth Schiff alkali complex, of which two metal centers are connected through a biphenyl skeleton. Under the action of single or nucleophilicity co-catalyst, the catalyst can be used for catalyzing the carbon dioxide efficiently to be copolymerized with the internal compensation alkyleneoxide under mild condition and lower concentration of the catalyst to prepare the makrolon, the makrolon can be regulated when the catalyst efficiency is 104-106g polymer/mole catalyst and the polymer molecular weight is between 103 and 105, the makrolon can be regulated when the molecular weight distribution is less than 2 and the vertical structure regularity is between 60-100%, an alternate structure exceeds 98% and the makrolon can be degraded into a small molecular compound. The product selectivity and structure selectivity of the polymer compounds of the catalyst system using a chiral ligand are all above 98%, the enantiomer excess value of the mellow obtained by degradation reaches as high as 99%, so that the bimetallic catalyst provides a broad prospect for industrial application.

Description

technical field [0001] The invention relates to a catalyst for synthesizing polycarbonate, in particular to a bimetallic catalyst for synthesizing stereoregularity polycarbonate by catalytically activating carbon dioxide and internal racemic alkylene oxide. Background technique [0002] CO in human daily life and industrial production 2 of excess emissions, making CO 2 become the main gas that causes the greenhouse effect. However, on the other hand, carbon dioxide is still one of the most important carbon sources on the earth, and is the most important part of the carbon cycle in nature. The chemical fixation of carbon dioxide is an important research field of green chemistry. Among them, the asymmetric alternating copolymerization of carbon dioxide and alkylene oxide to form polycarbonate is one of its most important applications. Under the action of catalyst, carbon dioxide can be copolymerized with alkylene oxide to prepare biodegradable polycarbonate. The high poly...

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Problems solved by technology

Japan has disclosed patents JP02142824 and JP02575199 using porphyrin complexes to catalyze carbon dioxide and alkylene oxide to synthesize polycarbonate, and the catalytic efficiency is as high as 10 3 ~10 4 gram of polymer / mole of catalyst, but the molecular weight of the polymer is only about 5000, and the reaction time needs more than 10 days

Japan's Nozaki (J.Am.Chem.Soc., 1999, 121, 11008-11009) and Coates (Chem.Commum, 2000, 2007-2008) respectively applied chiral bimetallic zinc complexes to catalyze epoxycyclohexane or Cyclopentene oxide and carbon dioxide are alternately copolymerized to prepare isotropic polycarbonate, but this method has low catalytic activity and the obtained polycarbonate is in an amorphous state, which makes it difficult to process polymer injection molding

The patent reported by our research group (CN102229745A, J.Am.Chem.Soc., 2012, 134, 5682-5688) uses an asymmetric Salen complex to catalyze the alternating copolymerization of epoxycyclohexane and carbon dioxide, and prepares a crystallized Polycarbonate, but requires a lower reaction temperature, especially the catalyst has very low activity for the copolymerization of cyclopentene oxide and carbon dioxide

[0004] Most of the above-mentioned methods for preparing polycarbonate have low catalyst activity, long reaction time, and high pressure, which requires an organic solvent; accompanied by the production of cyclic carbonate by-products or low carbonate units in the polymerization product; the catalyst and reaction in the reaction system The molar ratio of the substrate is high; the separation of the product and the catalyst is difficult, etc.

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