Catalyzed Carbon Dioxide Synthesis Of Quinazoline-2,4-(1H, 3H)-Diones With Green Method

In recent years, conversion of CO₂ to value-added chemicals has been being one of the hot topics. In this thesis, a green route of the transformation of CO₂ and 2-aminobenzonitriles to quinazoline-2,4（1 H,3 H）-diones was studied. Various organic polymers with multiple CO₂ adsorption and catalytic conversion functions were designed and prepared. The adsorption and catalytic conversion of CO₂ and the effect of the presence of azo bonds on the selective adsorption of CO₂/N2 were investgated. Furthermore, a green and economic catalytic CO₂ conversion route was also developed. The primary work was follows:1. In order to get the organic nitrogen containing materials with large free volume, specific surface area, porosity and high CO₂ adsorption amount, four kinds of organic polymers were designed and synthesized: p-phenylenediamine polyamidine（PDPA）, melamine polyamidine（MAPA） and 2,4,6-priaminopyrimidine polyamidine（TAPPA）, tetrakis（4-aminophenyl）methane polyamidine（FABPA）. The resultant polymers were characterized with various techniques and their adsorbabilities for CO₂ were investigsted.（1） Firstly, tetrakis（4-aminophenyl）methane was prepared after four steps of organic synthesis, whose structure was characterized by infrared（IR） and nuclear magnetic（13C NMR）.（2） Secondly, triethyl orthoformate（TEOF） was used to synthesis polyamidine with p-phenylenediamine, melamine, 2,4,6-triaminopyrimidine, and tetrakis（4-aminophenyl）methane under the specified reaction conditions, respectively. The resultant polyamidine materials were characterized with IR, 13 C NMR, X-ray photoelectron spectroscopy（XPS）, scanning electron microscopy（SEM）, and N2 adsorption-desorption. Their adsorbabilities for CO₂ were investigsted with an intelligent weight analyzer（IGA）.2. In order to realize the value-added conversion of CO₂, MAPA was used as catalyst for the catalytic transformation of CO₂ and 2-aminobenzontriles to quinazoline-2,4（1H, 3H）-diones. The influences of various reaction parameters, such as the dosage of the catalysts and cocatalysts（Na2CO3）, reaction time, pressure and temperature, on the yield of quinazoline-2,4（1 H,3 H）-diones were estimated. The results showed that the yield may reach up to 96% under the present conditions.3. The effect of reaction temperature on the yield were also studied for the the catalytic transformation of CO₂ and 2-aminobenzontriles to quinazoline-2,4（1H, 3H）-diones over melamine in organic solvent DMSO. Furthermore, in order to avoiding the harm of DMSO and realizing the highly efficient transformation of CO₂ to value-added chemicals in green solvent, the synthesis of quinazoline-2,4（1H, 3H）-diones over melamine with water as solvent. It is known that the solubility of melamine in water has the temperature sensitive characteristic, which could be dissolved completely at higher temperature and separated out at lower temperature. Therefore, as a catalyst, melamine could be recycled via a simple recrystallization method through decreasing the tempertute. The influences of the reaction temperature, time and pressure on the yield were investigated. The thermostability and reusability of melamine were also studied. In addition, the reaction mechanism was explored via the theoretical simulation. The results reveal that melamine has outstanding advantages including excellent catalytic performance, low-cost, and eco-friendly characteristic when used used as catalysts for the conversion of CO₂ to quinazoline-2,4（1H, 3H）-diones in water. Therefore, is expected to be used in industry.