Iron-Catalyzed Cross-Electrophile Coupling of Inert C-O Bonds with Alkyl Bromides

An example of iron-catalyzed cross-electrophile couplingof inert C-O bonds with alkyl bromides via aniron/B_(2)pin_(2) catalytic system has been developed.Aryl and heteroaryl carbamates can smoothly undergothis transformation under mild conditions, deliveringthe alkylated products with good efficiency.This protocol exhibits good functional group compatibilityand enables the late-stage functionalizationof biorelevant compounds, thus providingexcellent opportunities for applications in medicinalchemistry. Control experiments and computationalstudies reveal that a high spin Fe(I/II/III) catalyticmechanism might be involved in this reactionthrough single electron transfer to activate alkylbromides, oxidative addition of aryl carbamates, andreductive elimination to form Csp^(2)-Csp^(3) bonds.

Reductive Cleavage of C-O Bond in Model Compounds of Lignin

A simple protocol for reductive cleavage of C--O bond in diaryl and aryl methyl ethers was reported, in which Nail served as a reducing agent and KO Bu as a base and a radical initiator. The combination of Nail and KOBu displayed high efficiency for reductive cleavage of C-O bond in diaryl and awl ethers （e.g., dibenzofuran, diphe- nyl ether, anisole） without the hydrogenation of the aryl rings, in the absence of any other catalysts or ligands at 140 ℃, producing corresponding arenes and phenols. It was indicated that the reaction was under a radical mecha- nism.

Nickel-catalysed C-O bond reduction of 2,4,6-triaryloxy-1,3,5-triazines in 2-methyltetrahydrofuran

A nickel-catalysed reduction of phenol derivatives activated by 2,4,6-trichloro-1,3,5-triazine (TCT) in ecofriendly 2-methyltetrahydrofuran (2-MeTHF) is described. The phenol-TCT derivatives were readily prepared using grinding method in short time without further purification. This catalytic system allowed the facile C-O cleavage of phenol-TCT derivatives under mild reaction conditions with high efficiency and good functional group tolerance. Gram-scale reaction was also achieved. Particularly, sequential functionalization of phenol-TCT derivatives followed by C-O bond reduction could also be realized,affording the high value-added products in moderate to good yields.

Structural and electronic effects boosting Ni-doped Mo_(2)C catalyst toward high-efficiency C-O/C-C bonds cleavage

The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.

Ni/HZSM-5催化剂的孔道调控及其对C-O键的催化裂解

C-O桥键是褐煤有机质中重要的含氧官能团之一,通过切断C-O桥键可以实现褐煤的温和解聚,得到含有芳环和杂环的小分子化合物。本文通过碱刻蚀的手段制备了高分散Ni基多级孔HZSM-5催化剂,并对催化剂进行氮气脱吸附、扫描电镜和X-射线衍射仪等表征。HZSM-5在0.01 mol/L和0.1 mol/L的NaOH溶液处理下能够提高分子筛的比表面积和孔径,并且能保持分子筛的晶型结构。采用苯基苄基醚作为探针分子探究了催化剂的催化活性以及产物选择性,结果表明在反应温度为300℃时,Ni/Z0.01催化苯基苄基醚裂解的转化率接近100%,对甲苯和苯酚的选择性分别为34.9%和33.7%。因此,Ni/Z的孔道结构调控对C-O键的裂解及产物的选择性有重要作用。

Copper-Catalyzed C-C(O)C Bond Cleavage of Monoalkylated β-Diketone: Synthesis of α,β-Unsaturated Ketones

A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K3PO4) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .

基于氢化断裂木质素及其模型化合物C-O键的研究进展

基于不同氢化断键模式,从催化剂类型综述了目前木质素及其模型化合物的氢化断裂C-O键研究的进展。为木质素及其模型化合物的研究提供相关的理论和实践基础。

铜催化的C-H键活化生成C-O键的最新进展

芳烃酰氧类化合物一直是有机合成中一个重要的合成中间体,有许多的经典方法可以合成它,其中Cu催化的由C-H键直接转化为酰氧类化合物的方法提供了一种方便,简单,有效,廉价的途径,这篇综述仅对铜催化的C-H键活化生成C-O键,特别是生成芳烃酰氧类化合物的最新进展进行了小结。

C-H…O Hydrogen Bonds and π…π Interaction and the Crystal and Molecular Structures of 3-Nitro-benzylideneaniline-methyl-2’

The title compound (C14H12N2O2, Mr = 240.26) crystallizes in the monoclinic system, space group P21/a with a = 7.394(1), b = 21.334(3), c = 7.423(1) ? b = 89.82(1)? V = 1170.8(3) ?, Z = 4, Dc = 1.363 g/cm3, m(MoKa) = 0.93 cm-1 and F(000) = 504.00. The final R and wR are 0.0440 and 0.1370 for 2153 observed reflections (I > 2s(I)), respectively. The dihedral angle between the two phenyl rings is 52.9 and that between the NO2 group and its attached ring is 3.0. In the crystal, molecules are stacked along [100] through p…p interactions. The CH…O hydrogen bond (3.403 ? 120.4? laterally connects the stacks along [010] to form networks (001) which are further anti- parallelly connected by CH…O (3.382 ? 142.9) and p…p interactions extending along [001]. Also presented here is a brief study on the CH…O hydrogen bonds in nitro-substituted benzyl-ideneanilines which can be classified into five types, namely, )5(12R, )4(21R, )8(22R, )6(12R and )7(22R, with the first three occurring more often.

Cooperative C–H…O H-bonds in ‘Bay Area’and Crystal Structure of 1-(4-Methylphenyl)-3-(4-methoxyphenyl)-2-propene-1-one

The title compound (C17H16O2, Mr = 252.30) crystallizes in the monoclinic system, space group P21/c with a = 11.5763(14), b = 11.0321(11), c = 11.5094(13) ?, β = 114.581(3)o, V = 1336.7(3) ?3 , Z = 4, Dc = 1.254 g/cm3, μ(MoKa) = 0.081 cm-1 and F(000) = 536.00. The final R and wR are 0.0527 and 0.1285, respectively for 3058 observed reflections (I > 2σ(I)). In the title molecule, two phenyl rings are rotated oppositely with respect to the central part C(1)–C(2)=C(3)– C(4) (plane 3) and the dihedral angle between them is 14.8o. The phenone O(1) atom deviates from plane 3 by 0.291 ?. In the crystal the molecules form H-bond chains of R2 (6) and R2 (5) types 1 1 along [001]. The molecule chains interacted through three cooperative C–H…O H-bonds (R3 (11)) 1 in the ‘bay area’ (Fig. 3), extending along [010] and forming layer (100). Between the layers, there exist C–H/π interactions along [101]. Studies on the cooperative C–H…O H-bonds R3 (11) in the 1 similar crystals are also presented.

Cooperative catalysis of Co single atoms and nanoparticles enables selective CAr-OCH_(3) cleavage for sustainable production of lignin-based cyclohexanols

In this work,a dual-size MOF-derived Co catalyst(0.2Co_(1-NPs)@NC)composed of single atoms(Co_(1))and highly dispersed nanoparticles(Co NPs)was prepared by in-situ Zn evaporation for the highperformance conversion of lignin-derived o-methoxyphenols(lignin oil)to cyclohexanols(up to 97%yield)via cascade demethoxylation and dearomatization.Theoretical calculations elaborated that the dual-size Co catalyst exhibited a cooperative effect in the selective demethoxylation process,in which the Co NPs could initially dissociate hydrogen at lower energies while Co1remarkably facilitated the cleavage of the C_(Ar)-OCH_(3)bond.Moreover,the intramolecular hydrogen bonds formed in the omethoxy-containing phenols were found to result in a decrease in the bond energy of the C_(Ar)-OCH_(3)bond,which was more prone to be activated by the dual-size Co sites.Notably,the pre-hydrogenated intermediate(e.g.,2-methoxycyclohexanol from guaiacol)is difficult to undergo demethoxylation,indicating that the selective C_(Ar)-OCH_(3)bond cleavage is a prerequisite for the synthesis of cyclohexanols.The 0.2Co_(1-NPs)@NC catalyst was highly recyclable with a neglect decline in activity during five consecutive cycles.This cooperative catalytic strategy based on the metal size effect opens new avenues for biomass upgrading via enhanced C-O bond cleavage of high selectivity.

Atomically Dispersed Pt and NiO Clusters Synergistically Enhanced C–O Bond Hydrogenolysis

C–Obond activation is a highly efficient,fundamental strategy in the depolymerization and hydrodeoxygenation of chemicals with oxygen-containing functional groups such as oil,coal,and biomass.Developing efficient catalysts for C–Oactivation with ultralow-loading noble and non-noble metals is highly desirable for the improvement of metal atomic utilization.Herein,bimetallic catalysts with atomically dispersed Pt and NiO clusters on different supports were fabricated,and the prepared Pt^(δ+)-NiO/Nb_(2)O_(5)and Pt^(δ+)-NiO/TiO_(2)showed outstanding activity for the hydrogenolysis of benzyl phenyl ether with>99%yield of phenol and toluene due to the excellent cooperation of atomically dispersed Pt and NiO clusters.The synergy mechanism between Pt and Ni and their respective roles in the bimetallic catalyst for C–O hydrogenolysis were clearly clarified.These findings deepen our understanding of the synergy of the two active components and are expected to provide new design concepts for the development of multicomponents catalysts.

基于水溶性煤沥青的MnO@C复合材料的制备及储锂性能研究

目的制备出具有高容量、良好的倍率性能和循环稳定性的MnO@C复合电极材料。方法使用水溶性煤沥青及KMnO4为原料,通过水热法制备出Mn3O4@C前驱体。然后经过高温碳热还原制备MnO@C复合电极材料。通过SEM、XPS、XRD和Raman等分析技术对MnO@C复合材料的形貌、表面、结构等进行表征,并使用循环伏安、恒流充放电和电化学阻抗等电化学分析技术对其电化学性能进行了评价。结果TEM和SEM结果表明,制备的水溶性煤沥青表面丰富的含氧官能团与MnSO4溶液中的Mn2+之间有较强的相互作用,提供成核位点,进而促进了后续MnO@C材料中纳米颗粒的形成和均匀生长。这些纳米粒子的形成又起到了提升MnO@C电化学性能的作用。XRD、Raman和XPS结果表明,Mn3O4@C前驱体经过高温碳热还原反应生成MnO@C后,在MnO表面和包覆的碳材料之间生成了大量的Mn—O—C键。电化学结果表明,MnO@C电极在0.1 A/g电流密度下循环100圈后具有606.47 mAh/g较高的储锂容量,即使是在0.5 A/g大电流密度下循环400圈后仍具有293.83 m Ah/g的储锂容量。同时,电化学测试也表明,MnO@C复合材料具有非常好的倍率性能。结论使用鞍钢产的煤沥青根据混酸法制备了水溶性煤沥青。通过使用水溶性煤沥青和KMnO4成功地制备了Mn3O4@C前驱体。以Mn3O4@C前驱为原料,通过高温碳热还原法制备了MnO@C复合材料。在MnO表面包覆碳层不仅提供活性位点而且起到限制在充放电过程中MnO体积膨胀的作用。特别值得注意的是,Mn—O—C键构筑了MnO和碳层之间的快速导电通道,提升了电极反应动力学。

可见光诱导无金属催化合成邻四氢呋喃基苯乙酮肟醚

自由基反应作为有机化学的三大基本机理之一在实验教学中被长期忽略,造成理论与实践的脱节。本课题以苯乙酮肟和四氢呋喃为起始原料,在3 W蓝色LED光照下,由四溴化碳介导的经自由基历程构建C―O键合成邻四氢呋喃基苯乙酮肟醚,并利用核磁、红外、紫外手段对产物进行表征。本合成实验所需的设备简单、廉价,反应条件温和,且实验开设的普适性高。通过本实验的学习不仅可以让学生学习到溴自由基在有机合成中的应用,使学生能更好地理解和掌握自由基反应的过程,而且还能通过产物分子结构的分析,提高学生综合解谱的能力。

第5/6副族高价过渡金属氯化物的有机反应

从制备化学的角度,对包括作者本人的研究工作在内的由第5/6副族高价过渡金属氯化物参加的有机反应进行了综述.内容包括以下几个方面:(1)烷烃、烯烃和炔烃与第5/6副族高价过渡金属氯化物的卤化反应;(2)作为Lewis酸催化的反应;(3)烯烃歧化反应及炔烃的聚合反应;(4)MoCl5参与的芳烃氧化偶合反应;(5)硫醚化及扩环反应.

二联苯和氨基酸构建的大环化合物自组装研究

以二联苯作为模板,设计并合成了3个二联苯和氨基酸构建的大环化合物.晶体结构结果研究发现,在固态,这些大环化合物分别组装成了管状、三维网状和链状的超分子结构,其中,C—H…O氢键在维持这些大环的组装方面发挥了重要作用.这将有助于进一步增加对分子自组装、分子识别以及生物大分子的稳定性方面的理解.

纳米金属催化乌尔曼反应的研究进展

因纳米金属粒子具有大的表面积和高的反应活性,因此作为新型的催化剂在有机合成领域得到了越来越多的应用。主要从C—C键、C—N键、C—O键和C—S键的形成角度,概括了各种金属纳米粒子催化乌尔曼反应的研究进展。

HMX/DMF溶剂化物结构和分子间相互作用的理论研究(英文)

采用量子化学计算和分子动力学(MD)模拟,研究了溶剂化物环四亚甲基四硝胺(HMX)/N,N-二甲基甲酰胺(DMF)的结构和分子间相互作用。对浸渍在DMF溶剂中的β-HMX分子的MD模拟表明,HMX的分子构象已经从β转变为α相。在M P2/6-31G*水平上的理论计算也说明,在D M F溶剂中,α-HM X比β-HM X更稳定。这解释了在HM X/D M F溶剂化物的多晶型中,所有的HMX分子均呈α构象的原因。采用MP2/6-31G*方法,对α-HMX和DMF分子间可能的同型和异型二聚体进行结构优化。结果表明,组分间存在C—H…O氢键相互作用,并且α-HMX/DMF的稳定化能非常接近α-HMX/α-HMX,并远远大于D M F二聚体的。这意味着异型分子间力可和同型分子间力竞争。从热力学的观点来看,共结晶过程可能发生。对α-HM X在D M F中的过饱和溶液的M D模拟表明,分子间相互作用对共结晶有利。这些理论研究对理解在HM X的D M F溶液中为什么发生的是共结晶而不是重结晶提供了有价值的信息。

掺杂型锰氧化物La1-xSrxMnO3的电子结构研究

采用局域自旋密度泛函近似LSDA(local spin-density approximation)对La_(1-x)Sr_xMnO_3超晶格的电子结构进行了计算.计算结果与众多实验数据相一致.在完整的立方晶格结构中,计算发现,已经能够得到锰氧化物特有的半金属特性,这说明Jahn-Teller畸变对此类材料半金属性的形成不起主导作用.当考虑了晶格畸变后,发现晶体的电子结构对晶体c轴与a轴的长度比(c/a)的变化十分敏感,导电性发生了金属(c/a<1)—半金属(c/a=1)—绝缘体(c/a>1)的转变.

Bi系高温超导体Cu-O键伸缩振动频率的理论计算

根据分子振动理论，采用简化模型分析了Ｂｉ系高温超导体ＣｕＯ２面内Ｃｕ－Ｏ键的伸缩振动模式，计算了相应于各振动模式的振动频率，并将理论分析结果与实验结果进行了比较，分析结果表明Ｂｉ系高温超导体ＣｕＯ２面内Ｃｕ－Ｏ键的伸缩振动模式有拉曼活性模Ａ１ｇ，Ｂ１ｇ和红外活性模Ｅｕ，其中拉蔓模Ａ１ｇ，Ｂ１ｇ的振动频率分别为１２６．３ｃｍ－１和５７３．６ｃｍ－１，与实验确定的Ｂｉ系高温超导体Ｃｕ－Ｏ键伸缩振动拉曼模所处的频率范围相近，而红外模Ｅｕ的振动频率为３９９．０ｃｍ－１在实验分析所确定的Ｂｉ系高温超导体Ｃｕ－Ｏ键伸缩振动红外活性模的频率范围内．