@phdthesis{oai:sucra.repo.nii.ac.jp:00010430,
 author = {王, 林},
 month = {},
 note = {56 p., The synthesis of cyclic carbonates through coupling of carbon dioxide with epoxides is 100% atom economical and is already performed on an industrial scale. Its impact regarding the use of carbon dioxide as a renewable carbon source is expected to grow significantly in the near future, so that the development of efficient catalysts is of high interest in academia and industry. To improve the carbon footprint and sustainability of the cycloaddition reaction, the use of organocatalytic systems is a promising approach. In this thesis, during our study on the reaction of CO2 with epoxides, we focused on developing organocatalytic systems using inexpensive and readily available compounds and employing ambient CO2 pressure.
Herein, three different types of organocatalytic systems with enhanced properties for the chemical fixation of CO2 into cyclic carbonates were developed. Firstly, using 1 mol% of benzyl halide as the nucleophilic catalyst and 3-5 equiv. of DMF as the recyclable solvent and activator. Under ambient CO2 and 120℃, the catalyst system smoothly converted diverse terminal epoxides up to 99% yields. A plausible mechanism for the coupling reaction of epoxides with CO2 catalyzed by benzyl bromide and DMF was proposed. The ring opening of epoxides can be attributed to the electrophilic activivation of epoxides by benzyl cations and the nucleophilic activation of CO2 by DMF. Moreover, the activation of benzyl bromide by DMF was observed by 1HNMR study.
Secondly, a simple, inexpensive and efficient binaly organocatalytic system consisting of DBU and benzyl bromide was developed. A diverse range of epoxides was transformed into the corresponding cyclic carbonates with good to excellent yields (81-95%) under very mild conditions (65℃, 1 atm CO2). Furthermore, optically pure epoxides were also investigated, and a plausible mechanism for the coupling reaction of epoxide with CO2 was proposed.
Thirdly, a new, metal- and solvent-free, binary catalyst system consisting of commercially available pyridinemethanol as the hydrogen bond donors (HBDs) containing an organonitrogen component (pyridine) and nBu4NI as the co-catalyst for the cycloaddition of epoxides to ambient CO2, affording five-membered cyclic carbonates under ambient conditions. Furthermore, optically pure epoxides were converted to the corresponding cyclic carbonates with minimal loss in the ee values. Notably, the binary catalytic system, 2, 6-pyridinedimethanol/nBu4NI, is recyclable at least six times without any significant loss of activity, making this catalytic system sustainable and economical., 1. Introduction・・・・・1
1.1 Emission of CO2・・・・・1
1.2 CO2 as a Green C1 Resource・・・・・1
1.3 CO2 as a feedstock for synthesis of cyclic carbonates・・・・・2
1.3.1 Metal-based catalytic systems for the synthesis of cyclic carbonates・・・・・3
1.3.2 Metal-free organocatalytic systems for the synthesis of cyclic carbonates・・・・・5
1.4 Aim of the Thesis・・・・・6
2. Low loading of benzyl bromide/DMF as organocatalytic systemⅠ・・・・・7
2.1 Background・・・・・7
2.2 Results and discussion・・・・・8
2.3 Conclussions・・・・・15
2.4 Experimental Section and 1H and 13C NMR Spectral Charts・・・・・15
3. Metal - and solvent-free catalytic system : DBU/benzyl bromideⅡ・・・・・24
3.1 Background・・・・・25
3.2 Results and discussion・・・・・25
3.3 Conclusions・・・・・35
3.4 Experimental Section and 1H and 13C NMR Spectral Charts・・・・・35
4. An efficient and recyclable catalytic system under room temperatureⅢ・・・・・38
4.1 Background・・・・・38
4.2 Results and discussion・・・・・39
4.3 Conclusions・・・・・49
4.4 Experimental Section and 1H and 13C NMR Spectral Charts・・・・・49
5. Summary and outlook・・・・・50
6. References・・・・・51
7. Acknowledgements・・・・・56, 主指導教員 : 廣瀬卓司, text, application/pdf},
 school = {埼玉大学},
 title = {Chemical Fixation of CO2 into Cyclic Carbonates Catalyzed by Efficient Organocatalytic Systems under Metal-free and Mild Conditions},
 year = {2016},
 yomi = {ワン, リン}
}