Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)...Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)[Co(CO)_(4)]^(-)catalysts.However,the decomposition of[Co(CO)_(4)]^(-)species at temperatures exceeding 80℃presents a hurdle for the development of commercially viable processes under high-temperature reaction conditions to reduce reaction time.Drawing insights from stable{(acyl)Co(CO)n}intermediates involved in historical HCo(CO)_(4)-catalyzed hydroformylation processes,we sought to the high-temperature catalytic activity of epoxide ring-expansion carbonylation.The developed catalyst system,[(acetyl)Co(CO)_(2)dppp]and[(TPP)CrCl],exhibited exceptional catalytic performance with an unprecedented initial turnover frequency of 4700 h^(-1)at 100℃and a turnover numbers of 93000.Notably,the catalyst displayed outstanding stability,operating at 80℃for 168 h while selectively generatingβ-lactones.展开更多
Poly(3-hydroxyalkanoates) (PHAs) are a promising class of biodegradable polymers,exhibiting properties comparable to traditional petroleum-based counterparts.Nonetheless,the widespread commercialization of PHAs is hin...Poly(3-hydroxyalkanoates) (PHAs) are a promising class of biodegradable polymers,exhibiting properties comparable to traditional petroleum-based counterparts.Nonetheless,the widespread commercialization of PHAs is hindered by the absence of an efficient and economically viable catalytic system,impeding their competitiveness against non-biodegradable polymers.In an effort to address this challenge,we present a study on a newly developed chloro-bridged dimeric salphen zirconium cobaltate complex for the direct synthesis of PHAs via carbonylative polymerization of epoxides.The catalytic system demonstrates favorable activity under mild reaction conditions,enabling complete monomer conversion and an impressive 92% selectivity towards PHA formation.Through meticulous control experiments and mechanistic studies,we have gained crucial insights into the polymerization process.Remarkably,our findings challenge the prevailing notion of sequential ring-opening polymerization of in-situ generated β-lactones as the primary pathway.Instead,we demonstrate that the polymerization predominantly proceeds through direct co-polymerization of epoxide and carbon monoxide,unveiling a unique and efficient mechanism for PHA synthesis.展开更多
文摘Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)[Co(CO)_(4)]^(-)catalysts.However,the decomposition of[Co(CO)_(4)]^(-)species at temperatures exceeding 80℃presents a hurdle for the development of commercially viable processes under high-temperature reaction conditions to reduce reaction time.Drawing insights from stable{(acyl)Co(CO)n}intermediates involved in historical HCo(CO)_(4)-catalyzed hydroformylation processes,we sought to the high-temperature catalytic activity of epoxide ring-expansion carbonylation.The developed catalyst system,[(acetyl)Co(CO)_(2)dppp]and[(TPP)CrCl],exhibited exceptional catalytic performance with an unprecedented initial turnover frequency of 4700 h^(-1)at 100℃and a turnover numbers of 93000.Notably,the catalyst displayed outstanding stability,operating at 80℃for 168 h while selectively generatingβ-lactones.
基金supported by C1 Gas Refinery Program(2018M3D3A1A01018006)Direct Air Capture and Utilization(DACU)grant(RS-2023-00259920)through the National Research Foundation of Korea funded by the Ministry of Science,ICTFuture Planning,Republic of Korea.
文摘Poly(3-hydroxyalkanoates) (PHAs) are a promising class of biodegradable polymers,exhibiting properties comparable to traditional petroleum-based counterparts.Nonetheless,the widespread commercialization of PHAs is hindered by the absence of an efficient and economically viable catalytic system,impeding their competitiveness against non-biodegradable polymers.In an effort to address this challenge,we present a study on a newly developed chloro-bridged dimeric salphen zirconium cobaltate complex for the direct synthesis of PHAs via carbonylative polymerization of epoxides.The catalytic system demonstrates favorable activity under mild reaction conditions,enabling complete monomer conversion and an impressive 92% selectivity towards PHA formation.Through meticulous control experiments and mechanistic studies,we have gained crucial insights into the polymerization process.Remarkably,our findings challenge the prevailing notion of sequential ring-opening polymerization of in-situ generated β-lactones as the primary pathway.Instead,we demonstrate that the polymerization predominantly proceeds through direct co-polymerization of epoxide and carbon monoxide,unveiling a unique and efficient mechanism for PHA synthesis.
