tBu3P/ZnR2 (R=Et,I) Frustrated Lewis Pair Catalysts for Functionalization and Reduction of CO2

The functionalization and reduction of CO₂ are important targets not only because of concerns about its accumulation or the impact of this greenhouse gas on Earth’s climate, but also because of its potential as a C-1 feedstock. In this work, both functionalization and reduction of CO₂ were performed using tBu₃P/ZnR₂ (R=Et, I) “frustrated Lewis pairs” (FLPs). Phosphine-catalyzed carboxylation of alkyl-Zn bonds and catalytic reduction of CO₂ using silanes as hydride sources and tBu₃P/ ZnR₂ (R=Et, I) FLPs as catalysts are reported. This is also the first time Zn-based FLP chemistry in functionalization of CO₂ is reported.     

二氧化碳羧基化利用探讨

二氧化碳是一种低毒、不易燃、储量丰富且廉价易得的碳一资源,如何有效利用二氧化碳,将二氧化碳转化为高附加值化工品已成为当今研究热点。从能量利用及经济性角度考虑,将二氧化碳作为羧化试剂与具有高能量的起始原料反应,合成具有较高应用价值的羧酸（酯）或碳酸酯类衍生物是二氧化碳规模化利用的重要途径,目前受到了广泛关注。本文综述了近年来二氧化碳羧基化反应的研究进展,从反应的热力学、反应机理以及催化剂和反应工艺的改进等多个方面探讨了通过二氧化碳羧基化反应制备精细化工品的可行性及应用前景。并对该领域研究所存在的问题和局限性进行了总结。最后对今后的发展方向作了展望,指出二氧化碳化学工业的建立还需依赖基础研究的突破,需要开发高性能、廉价、适用范围广的过渡金属催化剂,实现二氧化碳的有效活化和利用。     

3,6-二氯水杨酸的合成研究

在二甲苯溶剂中，2，5—二氯苯酚与氢氧化钾共沸脱水后成盐，酚盐与C02进行高压羧基化反应制得3，6—二氯水杨酸，最高收率达78．7％，HPIC含量≥99．4％。     

Intramolecular Palladium‐Catalyzed Aminocarboxylation of Olefins as a Direct Route to Bicyclic Oxazolidinones

An efficient, direct synthesis of oxazolidinones fused to six‐membered heterocyclic rings starting from carbamate‐protected aminoalkenes has been developed. This procedure is based on an oxidative palladium(II)‐catalyzed reaction performed in the presence of stoichiometric copper chloride, which is determinant to promote the formation of the bicyclic product and prevent the isolation of the monocyclic amination product. Oxazolidinone compounds arise from a domino aminocarboxylation process through the direct intervention of the carbamate oxygen after the initial palladium‐promoted transfer of the nitrogen atom on the CC double bond.     

壳聚糖羧基化的研究进展

壳聚糖是一种生物来源丰富的天然高分子多糖,广泛应用于众多领域。概述了N,O-羧基化、N-羧基化、O-羧基化改性壳聚糖的制备方法。     

Evaluation of the Substrate Scope of Benzoic Acid (De)carboxylases According to Chemical and Biochemical Parameters

The enzymatic carboxylation of phenolic compounds has been attracting increasing interest in recent years, owing to its regioselectivity and technical potential as a biocatalytic equivalent for the Kolbe–Schmitt reaction. Mechanistically the reaction was demonstrated to occur through electrophilic aromatic substitution/water elimination with bicarbonate as a cosubstrate. The effects of the substituents on the phenolic ring have not yet been elucidated in detail, but this would give detailed insight into the substrate–activity relationship and would provide predictability for the acceptance of future substrates. In this report we show how the kinetic and (apparent) thermodynamic behavior can be explained through the evaluation of linear free energy relationships based on electronic, steric, and geometric parameters and through the consideration of enzyme–ligand interactions. Moreover, the similarity between the benzoic acid decarboxylases and the amidohydrolases superfamily is investigated, and promiscuous hydrolytic activity of the decarboxylase in the context of the hydrolysis of an activated ester bond has been established.     

异噁酰草胺的合成研究

对异噁酰草胺的合成方法进行了研究。采用3-甲基-3-戊醇为起始原料,经过Koch-Haaf羧基化反应和酯化反应合成2-乙基-2-甲基丁酸甲酯;2-乙基-2-甲基丁酸甲酯与乙腈反应转化为4-乙基-4-甲基-3-氧代己腈,进一步与羟胺进行环合反应得到氨基异噁唑衍生物,最后与2,6-二甲氧基苯甲酰氯缩合得到目标产物异噁酰草胺。产品质量分数为95.8%,产品外观为灰白色固体,以3-甲基-3-戊醇计,合成总收率为58.8%。     

二氧化碳与不饱和烃制备丙烯酸及其衍生物研究进展

CO₂高值转化是“双碳”目标大背景下碳利用的有效方式。过渡金属络合物催化的CO₂与不饱和烃羧化反应是合成丙烯酸及其衍生物的新路线,也是CO₂高值利用的新途径。本文总结了多种金属络合物（Ni、Pd、Cu等）在催化CO₂与烯烃偶联羧化、CO₂与炔烃或联烯还原羧化制丙烯酸及其衍生物中的应用,着重概述了不同催化体系中的金属-配体优化和反应条件调控,系统对比了不同催化剂的催化特点和作用机制,并论述了其催化反应循环中的控速步骤以及催化剂再生等关键问题。最后,对过渡金属络合物催化CO₂与乙烯偶联羧化制备丙烯酸及CO₂与炔烃或联烯还原羧化合成高区域选择性不饱和羧酸衍生物的后续研究方向和应用前景进行了展望。     

氢键作用对沥青质超分子聚集的影响

对沥青质进行羧基化、磺化和甲基化反应,从加强与钝化氢键作用两个方面对比研究了不同化学处理对沥青质结构、热稳定性以及沥青质聚集的影响.研究发现:羧基、磺酸基等基团引入沥青质分子后,提高了沥青质分子的极性,增强了分子间的氢键作用,显著促进了沥青质的聚集,并且引入的基团极性越强,促进聚集效果越明显;相反,沥青质中含活泼氢官能...     

Highly Efficient Direct Carboxylation of Propane into Butyric Acids Catalyzed by Vanadium Complexes

A direct and highly efficient carboxylation of propane by carbon monoxide into butyric acids (mainly isobutyric and, in a smaller amount, n‐butyric), in the presence of potassium peroxodisulphate (K₂S₂O₈) and in trifluoroacetic acid solution, has been achieved by using a vanadium catalytic system based on Ca[V{ON(CH(CH₃)COO)₂}₂] (synthetic amavadine), its model compounds Ca[V{ON(CH₂COO)₂}₂] or [VO{N(CH₂CH₂O)₃}] – other simpler vanadium compounds, such as [VO(acac)₂] or VOSO₄, are less active. Overall yields (based on propane) of carboxylic acids up to 70 % and TON values up to 18.4×10³ have been reached. The effects of various factors such as the propane and carbon monoxide pressures, temperature, time, catalyst amount and radical traps have been investigated, the reactions are shown to proceed via both C‐ and O‐centred radicals, with K₂S₂O₈ playing the role of an oxidant via a free radical mechanism.