无卤Cu配合物催化羰基化合成碳酸二甲酯

Dimethyl carbonate (DMC) is an important green product. Among the non-phosgene methods, the oxidative carbonylation of methanol to DMC as the green route is the hot spot of the study at home and abroad. The Cu catalytic system was widely reported in this reaction system. However, this catalytic system suffered from some urgent problems to be solved, such as the unconfirmed structure of the Cu catalyst, the uncertain effect of ligands, the anion only focused on the halogen ion, the corrosive effect on the reactor materials caused by the halogen ion, the low catalytic activity, and so on. In order to overcome these drawbacks, the complexes of Cu coordinated with 1,10-phenanthroline (phen) are selected as the catalysts in this project, and the influence of the substituent effect on phen, the structures and the anions on the catalytic activity of the complexes will be studied in detail. On the basis of the systematical study on the structure-activity relationship of the Cu complexes, which have different structures, different substituents and different anions, a reaction rule will be found, then the halogen-free Cu-phen catalysts will be prepared. With the introduction of the second ligand into the halogen-free Cu-phen complexes, the effect of the second ligand on the steric structures, electronic properties and catalytic performances of the complexes will be investigated, then the new type of the halogen-free Cu complexes with the high catalytic activity are developed. At last, the heterogenization of the homogeneous halogen-free Cu complex is realized with the aid of the shrinkage technology of the nano reactor. The heterogeneous Cu catalyst with the high efficience is exploited through the study on the activity of the catalyst and the reaction mechanism in the oxidative carbonylation.

碳酸二甲酯是重要的绿色化学品，其绿色合成工艺- - 甲醇氧化羰基化法是国内外研究的热点。针对国内外关于Cu系催化剂催化羰基化合成碳酸二甲酯反应中存在Cu催化剂的结构不确定、配体的效应不明确、阴离子集中于卤离子以及卤素离子腐蚀性、催化剂的活性低等问题，本项目以1,10-菲罗啉(phen)作配体的Cu配合物为催化剂，系统地研究phen上取代基效应、配合物结构、配合物阴离子对配合物催化活性的影响。通过对不同结构、不同取代基、不同阴离子的配合物构效关系的系统研究，找出活化作用规律，制备较佳的无卤Cu-phen配合物催化剂；通过对第二配体引入的研究，探讨第二配体对无卤Cu-phen配合物的空间结构、电子性能和催化性能的影响，开发高活性的混配型无卤Cu配合物催化剂；通过对纳米反应器缩孔技术的研究，实现混配型无卤Cu配合物的多相化，并通过对该催化剂的活性和反应机理的探索研究，指导高效固相无卤Cu催化剂的开发

碳酸二甲酯(DMC)是重要的绿色化学品。甲醇氧化羰基化法是绿色合成DMC的热点工艺，但该工艺存在催化剂的结构不确定、配体的效应不明确、卤离子的作用原理不清楚等问题。.针对上述问题，本课题以Cu2+-phen配合物(phen = 菲咯啉)为催化剂，从含卤Cu配合物的构效关系、催化反应机理、第二配体、无卤Cu配合物的固载等方面开展研究，得出如下结论：.①.催化反应中，phen和CuX2(X = Cl、Br)混合物仅能部分原位生成高活性的Cu(phen)X2是其活性低的原因；Cu配合物的配位数越多，热稳定性越低、阴离子占据的可交换位越少、空间位阻越大，活性越低；phen上取代基的甲基效应和位置效应显著，其中Cu(5-CH3-phen)Br2的活性最高，转化数(TON)和DMC选择性分别为53.8和98.3%。. ②.甲醇氧化羰基化反应属Cu+和Cu2+的协同催化机制，卤素离子在Cu+和Cu2+间起桥联作用，并设计模型物[Cu(phen)2Br]2[Cu4Br6]、[Cu(phen)2Br]Br、[Cu3I3(mphen)]n和[Cu3I3(phen)2]进行了验证，同时通过模型物还发现结构合适的非配位Cu中心具有比得上高活性配位Cu中心的活性。以氯离子为桥联原子时，高温反应还出现了新的歧化机制；添加三乙胺和N-乙基苄胺能调控Cu(phen)Cl2中n(Cu+)/n(Cu2+)在1:1左右，将TON从39.0分别提高到56.1和66.4。. ③.非卤Cu配合物中，[Cu(phen)(OAc)2]2(μ-H2O)和Cu(phen)NCS2具有较高的催化活性。以咪唑类/吡啶类为第二配体时，N-甲基咪唑和2-氨基吡啶对Cu(phen)NCS2有较好的促进作用。. ④.通过浸渍-交换法制备了固载Cu配合物催化剂，其中Cu(phen)(NCS)2/SBA-16的稳定性最好；采用甲基、丙基、苯基硅烷对Cu(phen)(NCS)2/SBA-16进行修饰后，以苯基硅烷修饰的Cu(phen)(NCS)2/SBA-16的孔口尺寸减小，稳定性最高，在优化条件下的 TON为32.9，可使用五次以上。. 本研究不仅开发了一批活性较高的催化剂，而且关于反应机理的研究成果为下一步非配位无卤型固相Cu催化剂的研发奠定了基础。