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Efficient Aluminum Catalysts for the Chemical Conversion of CO 2 into Cyclic Carbonates at Room Temperature and Atmospheric CO 2 Pressure
Author(s) -
Kim Yoseph,
Hyun Kyunglim,
Ahn Duseong,
Kim Ran,
Park Myung Hwan,
Kim Youngjo
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201901661
Subject(s) - furan , catalysis , epoxide , chemistry , heteroatom , medicinal chemistry , nitrogen , stereochemistry , organic chemistry , ring (chemistry)
A series of dimeric aluminum compounds [Al(OCMe 2 CH 2 N(R)CH 2 X)] 2 [X=pyridin‐2‐yl, R=H ( Pyr H ); X= pyridin‐2‐yl, R=Me ( Pyr Me ); X=furan‐2‐yl, R=H ( Fur H ); X= furan‐2‐yl, R=Me ( Fur Me ); X=thiophen‐2‐yl, R=H ( Thio H ); X= thiophen‐2‐yl, R=Me ( Thio Me )] containing heterocyclic pendant group attached to the nitrogen catalyze the coupling of CO 2 with epoxides under ambient conditions. In a comparison of their catalytic activities with those of aluminum complexes without pendant groups at N [X=H, R=H ( H H ); X=H, R=Me ( H Me )] or with non‐heterocyclic pendant groups [X=CH 2 CH 2 OMe, R=H ( OMe H ); X=CH 2 CH 2 NMe 2 , R=H ( NMe2 H ); X=CH 2 CH 2 NMe 2 , R=Me ( NMe2 Me )], complexes containing heterocycles, in conjunction with ( n Bu) 4 NBr as a cocatalyst, show higher catalytic activities for the synthesis of cyclic carbonates under the same ambient conditions. The best catalyst system for this reaction is Pyr H / ( n Bu) 4 NBr system, which gives a turnover number of 99 and a turnover frequency of 4.1 h −1 , making it 14‐ and 20‐times more effective than H H / ( n Bu) 4 NBr and H Me / ( n Bu) 4 NBr, respectively. Although there are no direct interactions between the aluminum and the heteroatoms in the heterocyclic pendants, electronic effects combined with the increased local concentration of CO 2 around the active centers influences the catalytic activity in the coupling of CO 2 with epoxides. In addition, Pyr H / ( n Bu) 4 NBr shows broad epoxide substrate scope and seven terminal epoxides and two internal epoxides undergo the designed reaction.