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A New Application Area for Ag‐NHCs: CO 2 Fixation Catalyst
Author(s) -
Taşcı Zeynep,
Kunduracıoğlu Ahmet,
Kani İbrahim,
Çetinkaya Bekir
Publication year - 2012
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201100430
Subject(s) - catalysis , chemistry , nucleophile , yield (engineering) , cycloaddition , selectivity , styrene oxide , medicinal chemistry , styrene , halide , solvent , propylene oxide , propylene carbonate , ionic liquid , polymer chemistry , organic chemistry , materials science , copolymer , polymer , electrolyte , ethylene oxide , metallurgy , electrode
The first example of the silver‐NHC catalyzed cycloaddition of CO 2 to terminal epoxides is reported. The choice of NHC substituents, halides and the nature of additives were determined to be important. Ionic [(C n mim) 2 Ag] 2 [Ag 2 Br 4 ] (C n mim=1‐(C n H 2 n +1 )‐3‐methylimidazol‐2‐ylidene; n =4–18) catalysts exhibited a high yield of styrene carbonate (77–92 %) in the presence of 4‐dimethylaminopyridine (DMAP) as a cocatalyst without needing any solvent. The catalytic activity improved as the length of the alkyl groups ( n ) increased, although substituents longer than C 14 did not produce any further beneficial effect. For the protocol performed at 1.5 M Pa pressure and 100 °C the TOF was calculated to be 440 h −1 . A prolonged reaction time and increased pressure of CO 2 increased the yield. Used without any additive, compound C 14 was able to fix CO 2 with PO (propylene oxide) quantitatively at 120 °C, 2.0 M Pa and could be used at least seven times without loss of activity and selectivity. The nucleophilic nature of the anion is decisive for the formation of the product.