Bond Character of β-Diketone Metal Chelates

The vibrational spectra of molecules labeled with ²H, ¹³C, and ¹⁸O show that delocalization of double and single bonds in the six-membered ring is complete in all the metal chelates investigated of 2,4-pentanedione (acetylacetone), but not in 2,4-pentanedione itself. Mercury, on the other hand, is bonded to the central C atom of the ligands. The NMR spectra of the metal chelates of 3-mesityl-2,4-pentanedione and 3-anthryl-2,4-pentanedione show that the chelate rings have no magnetic anisotropy comparable with that of benzene. A critical appraisal is made of the questions whether it is at all justifiable to attribute any “aromatic character” to such molecules and why all comparisons with the chemical reactivity of benzene have so far led to controversial conclusions concerning the character of the bonding in the metal chelates of 2,4-pentanedione.     

二茂铁基正庚基β-二酮的合成及晶体结构

在氢化钠存在下,用乙酰基二茂铁与正辛酸乙酯进行缩合反应,合成了标题化合物FeCOCH2COC7H15(Fc=C5H5FeC5H4).X射线衍射测定其晶体学数据为:C20H26FeO2,空间群P21/n,a=0.5790(1)nm,b=4.1634(4)nm,c=0.7635(1)nm,β=101.39(1)°,Z=4.最终的偏离因子R=0.050.结构分析表明,该化合物分子以烯醇式形式存在,通过分子内氢键,形成六元环,环中O…H氢键距离为0.146nm.β-二羰基中与正庚基相连接的羰基易于烯醇化。     

丙烯选择氧化制丙烯酸杂多酸催化剂的探索

丙烯选择氧化制丙烯酸是丙烯有效利用的途径之一 .目前工业上采用两步法生产 ,即丙烯先被氧化为丙烯醛 ,丙烯醛再被氧化为丙烯酸 .两步法中所使用的催化剂多为复合氧化物[1 ] .杂多酸催化剂由于富含晶格氧 ,有可能使丙烯一步被氧化为丙烯酸 [2 ] .其中具有 Keggin结构的杂多酸易于制备 ,化学稳定性及热稳定性好 ,被广泛用作多相选择氧化反应的催化剂 .我们选取 Keggin结构的杂多酸催化剂 ,调变其阴阳离子组成 ,用于丙烯一步氧化制丙烯酸 ,并对反应条件进行了考察 .1实验部分1 .1催化剂制备含铜、铬的杂多酸催化剂的制备方法见文献[3] .将三…     

ACC对羰基化合物、含苄基化合物及稠环芳烃中活泼碳氢键的选择性氧化

前文曾报道了几种以铵盐或氯化铵为配体与三氧化铬所形成的配合物(CH_3)_3NHCrO_3Cl、(CH_3)_2NH_2CrO_3Cl、CH_3NH_3CrO_3Cl和NH_4CrO_3CI。它们都是高效、温和的醇和肟类选择性氧化剂。其中,NH_4CrO_3Cl(ACC)是最廉价的,具有制备简单、性质稳定、选     

B2pin2-mediated copper-catalyzed oxidation of alkynes into 1,2-diketones using molecular oxygen

An intriguing aerobic oxidation of alkynes through copper catalysis is described, in which bis(pinacolato)diboron (B₂pin₂) played a dominant intermediary role in the formation 1,2-diketones. This novel protocol, which can be performed at room temperature, is versatile for various substituted alkynes, including diarylalkynes and arylalkylalkynes. The mechanism of this reaction was preliminarily investigated by control experiments.     

N,N-二甲基甲酰胺吸收氮氧化物对1,2-二芳基肼的氧化

报道了将NO~X废气吸收在N,N-二甲基甲酰胺(DMF)中氧化1,2-二取代芳基肼制备对称的偶氮化合物。结果表明,DMF-NO~X是一种优良的氧化体系,在温和的条件下,高产率地将8个1,2-二取代芳基肼氧化为相应的偶氮化合物。     

Oxidation reactions of 1,3-diphenylpropane-1,3-dione

The free radical scavenging properties and possible antioxidant activity of 1,3-diphenylpropane-1,3-dione (1) are reported. Pulse radiolysis technique was employed to study the one-electron oxidation of 1 with various radicals viz. CCl₃O₂ ^•, N₃ ^• and^•OH in homogeneous aqueous solution. All these radicals reacted with 1 under ambient conditions at almost diffusion controlled rates producing transient species with an absorption maximum around 420 nm that decayed at first order rates. The transient absorption peak was shifted in the case of CCl₃OO^• radical reaction with 1 due to change in the polarity of the medium. Formation of a stable product with a broad absorption band starting from 400 nm and cut off at 230 nm was observed in the oxidation of 1 with^•OH and^•N₃ radicals. In a biological system also, 1 showed significant inhibitory activity against Fe²⁺-mediatedlipidperoxidation. Based on these observations, a suitable mechanism for the oxidation of 1 has been proposed.     

微波辐射下蒙脱土K10固载氯化铁氧化二芳基乙醇酮

微波辐射下以蒙脱土K-10固载氯化铁为氧化剂, 氧化二芳基乙醇酮生成二芳基乙二酮化合物, 反应时间短, 产率高, 操作简便, 污染小, 是一种有效的由二芳基乙醇酮氧化制备二芳基乙二酮的方法.     

手性1,2-二苯基-1,2-乙二胺及其衍生物在不对称合成中的应用

含有C2 对称轴的1,2-二胺在不对称合成中得到了广泛的应用.综述了手性1,2-二苯基-1,2-乙二胺及其衍生物的合成,以及作为手性辅助基和手性配体在不对称合成中的应用.     

钼基复合氧化物在异丁烯选择氧化制甲基丙烯醛反应中的催化性能

研究了添加不同助剂对钼基复合氧化物催化剂对异丁烯选择性氧化制备甲基丙烯醛反应的影响. 结合XRD, TPR 和FTIR等表征手段对催化剂的结构进行了研究. 结果表明, 加入适量的铋能够提高催化剂的性能, 铁和钴元素能明显改变催化剂结构和表面性能, 从而提高异丁烯的转化率和甲基丙烯醛的选择性. 同时发现某种特定晶相及晶相之间的协同作用是提高催化剂性能的关键.筛选出在最佳催化剂上异丁烯的转化率为99.9%, 甲基丙烯醛的选择性为88.7%.     

担载纳米金催化乙醇选择氧化制乙酸乙酯

采用溶胶-凝胶法制备了一系列担载纳米金催化剂，用以催化乙醇选择氧化反应，模板剂的引入改变了催化剂载体的结构，从而提高了其催化活性和对乙酸乙酯的选择性，同时考察了反应温度、时间、以及催化剂制备方法对乙醇选择氧化反应的影响，实验结果表明使用以焙烧处理除去模板剂十八胺的Au／SiO2-O(C)为催化剂时，乙醇选择氧化一步制取乙酸乙酯的效果最佳，其选择性最高可达88．1％。     

Oxidation of Long Chain Primary Alcohols to Acids over the Quaternary Ammonium Peroxotungstophosphate Catalyst System

Factors influencing the catalytic properties for long chain primary alcohol oxidation to acid over quaternary ammonium peroxotungstophosphate catalyst were investigated. The catalysts were characterized by means of IR and NMR techniques. Based on the experimental results, the catalyst active centers for the title reaction were elucidated and optimal reaction conditions given.     

Ti-ZSM-11的合成、表征及苯乙烯选择氧化反应的研究

通过3种不同的水热晶化法合成了Ti-ZSM-11型分子筛,并利用XRD、SEM、IR、TG-DTA、XPS、DRS等手段对其进行了表征。结果表明,Ti进入了分子筛骨架,且Ti含量增加,晶胞参数增大,IR谱中～970cm^-1的谱带逐渐增强。热分析表明,Ti-ZSM-11有较好的热稳定性,苯乙烯选择氧化结果表明,沸石中Ti含量增加,反应活性提高,活性中心Ti是孤立的连接,而不是彼此邻近相连。     

金属卟啉催化烷烃选择性氧化反应的研究进展

金属卟啉作为一种仿生催化剂,能够实现在温和条件下对分子氧的催化活化,在催化烷烃氧化反应中显现出巨大的潜力.本文总结了金属卟啉结构对烷烃选择性氧化结果的影响,并介绍了近期金属卟啉催化剂应用于烷烃氧化反应的研究进展,最后探讨了金属卟啉催化剂在催化烷烃选择性氧化反应中存在的问题及发展前景.     

Synthesis of Mesoporous Cu-Mn-Al_2O_3 Materials and Their Applications to Preferential Catalytic Oxidation of CO in a Hydrogen-rich Stream

A series of mesoporous Cu-Mn-Al2O3(CMA) materials was synthesized at moderate temperature and their structures were characterized by XRD, N2 physical adsorption and TPR techniques. It was found that using metal complex ion[Cu(NH3) 42+-Mn(NH3)62+] as raw materials is easier to form good-structure mesoporous Cu-Mn-Al2O3 materials than using its nitrate salt [Cu(NO3)2-Mn(NO3)2]. The TPR tests results indicate that CuO and MnOx were homogeneously dispersed in the mesoporous materials. Their catalytic application to preferential catalytic oxidation of CO in a hydrogen-rich stream was studied. The activity varies in the order of CMA(1:1, molar ratio) CMA(1:2)CMA(2:1)CMA(CP)CMA(1:0)≈CMA(0:1). The CMA(1:0) and CMA(0:1) have lower activity compared to other samples, implying that there existed coordination effect between Cu-Mn in the samples. The selectivity varied in the order of CMA(0:1)≥CMA(1:2)CMA(1:1)CMA(2:1)CMA(1:0) at higher temperature (≥120 °C), indicating that increasing the Cu content enhanced the conversion of H2. The sample CMA(CP) made by coprecipitation method has a lower CO oxidation activity and selectivity than its counter-parts of mesoporous Cu-Mn-Al2O3 materials[CMA(1:2)], this attributed to the lower surface area of the former and poor interaction of CuO with MnOx.     

Pd-Y合金膜的MOCVD研制

采用金属有机化合物的化学气相淀积法,以β-二酮螯合物为源物质,在多孔Al₂O₃衬底上成功制备了超薄钯钇合金膜.用Pd(AcAc)₂+Y(AcAc)₃混合源制备的钯钇合金膜的晶粒尺寸(21nm×10nm)比单独用Pd(AcAc)₂制备的钯膜的尺寸(30nm×10nm)小.XPS研究发现,制备的Pd-Y合金膜中Y/Pd比小于源物质的.氢的透气性实验表明,合金膜的氢渗透率高于Pd膜,且在200～350℃范围内渗透率稳定.     

丙烷选择氧化催化剂Mo-V-Zr-O的研究

研究了Zr添加量对Mo-V-O基催化剂丙烷选择氧化制丙烯醛催化性能的影响.对催化剂的BET、X射线衍射、H2-程序升温还原、NH3-程序升温脱附和异丙醇分解表征结果表明,Zr的添加改变了催化剂的物相结构、氧化还原性和酸碱性质,从而影响催化剂的催化性能,其中Mo2VZr0.5Ox催化剂表现出较好的催化活性和丙烯醛选择性.     

相转移催化下肟类的选择性间接电氧化研究

以Ｃｅ＾４＋／Ｃｅ＾３＋为间接电氧化还原体系，在相转移催化剂ＰｈＣＨ２Ｎ（Ｃ２Ｈ５）３Ｃｌ存在下，对肟类化合物进行选择性间接电氧化。结果表明，在室温条件下，电解２ｈ，肟类能被选择性地氧化为相应的羰基化合物，收率７５－９５．６％。     

A Convenient Synthesis of 2-Arylnaphtho[1,2-d]oxazole Derivatives Promoted by Triethylamine

A variety of 2-arylnaphtho[ 1,2-d]oxazole derivatives were efficiently synthesized in moderate to high yields by the reaction of aromatic aldehydes with 1-amino-2-naphthol derivatives in the presence of triethylamine in refluxing ethanol in air. Seven new 2-arylnaphtho[1,2-d]oxazole derivatives were obtained and characterized by the spectral data and elemental analysis. In addition, the X-ray crystal structures of 2-[4-（N,N-dimethylamino）phenyl]naphtho[ 1,2-d] oxzole （3d） and 1, 1＇-bis（naphtho[ 1,2-d]oxazol-2-yl）ferrocene （3n） have been determined.     

电催化醇选择性氧化为醛酮的研究进展

醇选择性氧化为相应的羰基化合物是有机化学中最常用的生成羰基化合物的反应,电催化氧化具有反应条件温和、环境友好等优点,是一种非常有前途的醇催化氧化绿色生产工艺.我们综述了直接和间接电催化氧化反应的方法,并对各类体系的催化效果进行了简要介绍.