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Moderate route for the utilization of CO<sub>2</sub>-microwave induced copolymerization with cyclohexene oxide using highly efficient double metal cyanide complex catalysts based on Zn<sub>3</sub>[Co(CN)<sub>6</sub>]
<P>Zn<SUB>3</SUB>[Co(CN)<SUB>6</SUB>] based double metal cyanide complexes are currently used as catalysts for both the ring-opening polymerization of epoxides and the copolymerization of epoxides and CO<SUB>2</SUB>. This paper reports an environmentally friendly route for the copolymerization of cyclohexene oxide (CHO) with CO<SUB>2</SUB> using microwave irradiation. The reaction occurred over a faster reaction time (2–30 min) and a much lower pressure (9.7 bar) than conventional methodologies giving a high molecular weight (19.3 kg mol<SUP>−1</SUP>) polycarbonate with a higher level of CO<SUB>2</SUB> incorporation (<I>f</I><SUB>CO<SUB>2</SUB></SUB> = 75%). The catalysts were prepared from an aqueous solution of ZnX<SUB>2</SUB> and K<SUB>3</SUB>[Co(CN)<SUB>6</SUB>] using <I>tert</I>-butanol and polyethers as complexing agents. All the catalysts were characterized by elemental analysis, ICP-OES, XRD, XPS and IR spectroscopy. The catalysts were found to be highly selective for the copolymer with a high TOF (TOF = 25 177 h<SUP>−1</SUP>) values. Unlike conventional synthesis, there was no induction period noticed for the catalyst to initiate copolymerization. The high reactivity and excellent properties of the copolymer might be due to the higher activation of CHO by microwaves due to its high polarizability and higher dielectric constant.</P> <P>Graphic Abstract</P><P>A double metal cyanide complex catalyzed rapid process for the effective utilization of CO<SUB>2</SUB> by the copolymerization with cyclohexene oxide is established through microwave irradiation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b801132j'> </P>
<P>A double metal cyanide complex, an efficient catalyst for the copolymerization of CO<SUB>2</SUB> with epoxide, was successfully utilized for the cycloaddition of CO<SUB>2</SUB> to various epoxides in the presence of quaternary ammonium salts without any solvents.</P> <P>Graphic Abstract</P><P>A new catalyst system comprising a double metal cyanide complex with quaternary ammonium salts is derived for the cycloaddition of CO<SUB>2</SUB> to epoxide. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b916875n'> </P>
The synthesis of cyclic carbonate from butyl glycidyl ether (BGE) and carbon dioxide was performed in the presence of quaternary ammonium salt catalysts. Quaternary ammonium salts of different alkyl group (C₃, C₄, C6 and C8) and anions (Cl-, Br-, and I-) were used for this reaction carried out in a batch autoclave reactor at 60–120℃. The catalytic activity increased with increasing alkyl chain length in the order of C₃ < C₄ < C6. But, the quaternary ammonium salt with longer alkyl chain length (C8) decreased the conversion of BGE because it is too bulky to form an intermediate with BGE. For the counter anion of the tetrabutyl ammonium salt catalysts, the BGE conversion decreased in the order Cl- > Br- > I-. The effects of carbon dioxide pressure and reaction temperature on this reaction were also studied to better understand the reaction mechanism.
with methanol was investigated by using imidazolium salt ionic liquid catalysts. 1-alkyl-3-methyl imidazolium saltsof different alkyl group (C2, C4, C6, C8) and anions (Cl, Br,BF4, PF6) were used for catalysts. The reaction was carriedout in an autoclave at 140-180oC under carbon dioxide pressure of 1.48-5.61 MPa. The imidazolium salts of shorteras CO2 pressure and reaction temperature increased. Kinetic studies were also performed to better understand the reac-tion mechanism.
The catalytic performance of pyridinium salt ionic liquids in the reaction of butyl glycidyl ether and carbon dioxide was investigated in this study. The catalytic activity was studied in a batch reactor with different 1-alkylpyridinium salt ionic liquids at 60-140 oC. The conversion of butyl glycidyl ether was affected by the structure of the ionic liquid; the one with the cation of bulkier alkyl chain length showed better reactivity. The effect of carbon dioxide pressure, reaction temperature and zinc bromide co-catalyst on this reaction was also discussed.
A silica-supported ionic liquid (Im-IL) was proven to be an effective heterogeneous catalyst for solventless synthesis of cyclic carbonate from allyl glycidyl ether (AGE) and carbon dioxide. Im-IL catalysts were prepared by sol-gel method. The synthesis of cyclic carbonate from AGE and CO2 was carried out in a batch autoclave reactor. Im-IL with shorter alkyl chain length showed the highest conversion of AGE, probably due to the steric hindrance for the formation of intermediate from the catalyst prepared by using longer alkyl chains and AGE. High temperature and high pressure were favorable for the conversion of AGE. Im-IL can be reused for the reaction up to two consecutive runs without any considerable loss of its catalytic activity.