Copolymerization of CHO/CO₂ catalyzed by a series of aluminum amino-phenolate complexes and insights into structure–activity relationships

Abstract

Five aluminum catalysts demonstrated different selectivity and activity during reactions of carbon dioxide and epoxides.

Indium-Catalyzed CO2/Epoxide Copolymerization: Enhancing Reactivity with a Hemilabile Phosphine Donor

“…We tested the effect of temperature on the reaction: At 60 °C the conversion dropped to 32% (Table , entry 11), and at 25 °C no conversion was observed. These results are in alignment with the phenolate aluminum complexes reported by the Kerton group (Chart , B and C ) . Lowering CO 2 pressure to 10 bar resulted in slightly higher conversion at 64% but lower selectivity for polycarbonate (62%) (Table , entry 12).…”

“…These results are in alignment with the phenolate aluminum complexes reported by the Kerton group (Chart 1, B and C). 41 Lowering CO 2 pressure to 10 bar resulted in slightly higher conversion at 64% but lower selectivity for polycarbonate (62%) (Table 1, entry 12). No conversions were obtained when testing the reaction at 1 bar, which is in contrast to the indium complexes reported by Williams and coworkers (Chart 1, F) which are active at 1 bar.…”

“… For example, in 2005, Darensbourg and co-workers reported aluminum complex A supported by a salen ligand that is active for CO 2 /cyclohexene oxide copolymerization at 80 °C and 35 bar . More recently, Kerton and co-workers reported aluminum complexes B and C that are active at 80 °C and 40 bar when used with [PPN]Cl cocatalyst. − They illustrated that the morpholine donors in B and C promote the dissociation of chloride from the metal center to initiate the ring-opening of the epoxide. Hasegawa, Nozaki, Ema, and co-workers reported active aluminum porphyrin complexes D that can reach 10000 h –1 turnover frequency and produce polymers with M n values up to 281000 g mol –1 at 120 °C and 20 bar .…”

Catalytic Formation of Cyclic Carbonates using Gallium Aminotrisphenolate Compounds and Comparison to their Aluminium Congeners: A Combined Experimental and Computational Study

“…It should be noted that the AlLCl catalyst gives the lowest overall energy span (TDI→TDTS, see Figure 2), contrary to the experimental evidence, both GaL Me and GaL Cl have overall lower energy requirements starting from their respective initial catalyst structure. This brings to light the question if static energetics, and energy spans, are enough to fully understand complex catalytic reactions; a point recently raised in a related catalytic system by Kerton [38] …”

Progress in the catalytic reactions of CO2 and epoxides to selectively provide cyclic or polymeric carbonates

“…6f ). 14 Moreover, in the presence of PPNCl, all reported complexes except 5 acts as well-controlled catalyst systems that produce selectively alternating copolymers from CHO/CO 2 . Among these the best selectivity for poly (cyclohexenecarbonate) vs. the cyclic product (cyclohexene carbonate) was obtained with the morpholinyl complex (ca.…”