Feng Xiantao, Wang Guan, Zheng Tingting, Zuo Chunshan, Zhang Xihong, Fyffe Phoebe, Chen Xiaobo
Department of Chemistry, University of Missouri, Kansas City, MO, 64110, USA.
School of Chemistry and Pharmaceutical Engineering, Huanghuai University, NO. 76, Kaiyuan Road, Yicheng Dsitrict, Zhumadian, China.
Phys Chem Chem Phys. 2021 Sep 29;23(37):21130-21138. doi: 10.1039/d1cp03747a.
As global warming due to CO emissions has become a widely recognized concern, CO capture, sequestration, neutralization, and conversion have become possible solutions to address this concern. Among these approaches, the conversion of CO into fuels or value-added products has attracted considerable attention. In this work, we report the high-efficiency conversion of CO to important industrial raw materials for pharmaceutical compounds, quinazoline-2,4(1,3)-diones, reactions with 2-aminobenzonitriles at room temperature and under ambient pressure, with high conversion yields (91.5-99.3%). 1,8-Diazabicyclo-[5.4.0]-undec-7-ene (DBU), 1,1,3,3-tetramethylguanidine (TMG), and cholinium (Ch) ammonium-based ionic liquids (ILs) are employed as catalysts during the process. Cations with a p value near 11.9 and anions with a p value range of 10 to 15 are necessary for the reaction. The experimental results indicate that the ionic liquid pair [HDBU][3-Cl-PhO] has high efficiency under very mild conditions, obtaining high product yields of 91.5% at 25 °C and 1 atm and 99.3% at 30 °C and 1 atm. More importantly, the catalysts retain high efficiency and activity after 5 consecutive cycles. To gain insightful understanding of the reaction, density functional theory (DFT) calculations were conducted to study the reaction mechanism. The computational results indicate that the catalytic process contains three stages: cyano activation, intramolecular rearrangement, and intramolecular cyclization. Of these, the rate-determining step is cyano activation, which shows an energy barrier of 24.5 kcal mol. Tuning the types of ions in ILs can effectively reduce this energy barrier and allow high efficiencies.
由于二氧化碳排放导致的全球变暖已成为一个广泛认可的问题，二氧化碳的捕获、封存、中和及转化已成为解决这一问题的可能方案。在这些方法中，将二氧化碳转化为燃料或增值产品引起了相当大的关注。在这项工作中，我们报道了在室温及常压下，二氧化碳高效转化为药物化合物喹唑啉 -2,4(1,3)-二酮的重要工业原料，与2-氨基苯甲腈反应，转化率很高（91.5 - 99.3%）。在此过程中，1,8 - 二氮杂双环-[5.4.0]-十一碳 -7 - 烯（DBU）、1,1,3,3 - 四甲基胍（TMG）和胆碱（Ch）铵基离子液体（ILs）被用作催化剂。反应需要p值接近11.9的阳离子和p值范围为10至15的阴离子。实验结果表明，离子液体对[HDBU][3 - Cl - PhO]在非常温和的条件下具有高效率，在25℃和1个大气压下产物产率高达91.5%，在30℃和1个大气压下为99.3%。更重要的是，催化剂在连续5个循环后仍保持高效率和活性。为了深入了解该反应，进行了密度泛函理论（DFT）计算以研究反应机理。计算结果表明，催化过程包含三个阶段：氰基活化、分子内重排和分子内环化。其中，速率决定步骤是氰基活化，其显示出24.5千卡/摩尔的能垒。调整离子液体中的离子类型可以有效降低这一能垒并实现高效率。
