基于四氮配体的铜配合物/TEMPO催化的苄醇与烯丙基醇的氧化反应

发展了非血红素类四氮配体的铜配合物和2,2,6,6-四甲基哌啶-氮-氧自由基(TEMPO)相结合的催化体系,应用于分子氧参与的伯醇氧化反应.该体系具有条件温和、高效、高选择性、无需任何助剂和底物(包括苄醇、烯丙基醇和含杂原子伯醇)使用性强等优点.此外,利用高分辨质谱和紫外-光谱等对反应活性中间体进行了初步探讨.     

树枝状聚酰胺胺负载TEMPO的合成及其催化分子氧氧化醇的性能

以乙二胺和丙烯酸甲酯为原料,经过重复Michael和酯氨解反应,制备出二代(2.0 G)树枝状聚酰胺胺(PAMAM).PAMAM与2,2,6,6-四甲基哌啶酮氮氧自由基经缩合、还原将PAMAM与2,2,6,6-四甲基哌啶氮氧自由基(TEMPO)键连,得到PAMAM负载的TEMPO(PAMAM-TEMPO).采用1H NMR、13C NMR以及FT-IR等手段对中间体及最终产物进行了表征.将PAMAM-TEMPO与CuBr2以及2,2-联吡啶结合构成催化体系,用于分子氧为氧化剂的醇的选择性氧化反应,结果表明该体系对苄基以及烯丙基伯醇的氧化显示出良好的催化活性和选择性.结果还证明,TEMPO的负载使氧化产物醛很容易与催化体系分离,而且催化剂可以循环使用.     

可再生型高价碘试剂亚碘酰二内酯在高效醇氧化中的应用研究

利用商品化的高价碘试剂亚碘酰二内酯(Iodosodilactone)作为最终氧化剂, 配合催化量的氮氧自由基2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)和当量的4-二甲氨基吡啶(DMAP)所组成的反应体系可以将含有不同官能团的伯醇快速高效地氧化为相应的醛且不会发生过度氧化; 将反应体系中的催化剂换为空间位阻较小的氮氧自由基1-甲基-2-金刚烷氮氧自由基(1-Me-AZADO)则可以将仲醇高效地氧化为相应的酮. 值得指出的是, 反应结束后Iodosodilactone的还原态2-碘-间苯二甲酸和DMAP可以通过简单的过滤及酸碱中和处理进行回收, Iodosodilactone的再生可通过用次氯酸钠/盐酸体系氧化2-碘-间苯二甲酸来高效实现.     

β-环糊精负载四甲基哌啶氮氧化物的合成及其在分子氧氧化醇反应中的催化性能

以乙烯基二胺为连接臂将四甲基哌啶氮氧化物(TEMPO)负载于β-环糊精(β-CD)上,得到负载型催化剂β-CD-TEMPO.采用~1H NMR、~(13)C NMR以及FT-IR等手段对β-CD-TEMPO进行了表征.将β-CD-TEMPO、CuBr_2以及K_2CO_3结合构成催化体系,用于分子氧为氧化剂的醇的选择性氧化反应,结果表明该体系对苄基以及烯丙基伯醇的氧化显示出良好的催化活性和选择性.在负载催化剂中,乙烯基二胺既作为连接臂又作为配体与铜离子配位,使氧化反应顺利进行.负载型催化剂β-CD-TEMPO与产物容易分离,能够循环使用.     

偶联剂2-(4-异硫氰基苄基)-1,4,7,10-四氮杂环十二烷四乙酸的合成工艺改进

以对硝基苯丙氨酸和乙二胺为原料,经酯化、胺解、成环、烷基化、还原、取代等反应合成了目标产物2-(4-异硫氰基苄基)-1,4,7,10-四氮杂环十二烷四乙酸(p-SCN-Bz-DOTA),总产率为10.4%。反应中使用NaBH4/BF3体系代替甲硼烷作为还原剂,提高了操作过程的安全性;使用溴乙酸叔丁酯代替溴乙酸作为烷基化试剂,提高了烷基化的反应产率,而且避免了使用制备型高效液相色谱,降低了合成成本。     

1,3,5,7-四乙酰基-1,3,5,7-四氮杂环辛烷合成反应中间体的制备分离

1,3,5,7-四乙酰基-1,3,5,7-四氮杂环辛烷(TAT)是高能炸药奥克托今(HMX)重要的合成反应前体之一,1,5-二乙酰基-1,3,5,7-四氮杂环辛烷(DAPT)醋酐酰解法和乙腈甲醛小分子缩合法均能制备得到TAT.采用半制备高效液相色谱制备分离了上述两种制备方法反应原液中的六种中间体,分别是1-乙酰氧甲基-3,5,7-三乙酰基-1,3,5,7-四氮杂环辛烷、1,3,5-三乙酰基-1,3,5,7-四氮杂环辛烷、1-乙酰氧甲基-3,5,7-三乙酰基-1,3,5,7-四氮杂环辛烷、N,N’-亚甲基二乙酰胺、三乙酰胺二亚甲基三胺和四乙酰胺三亚甲基四胺,为反应机理研究提供了有力的证据.DAPT醋酐酰解法反应原液样品的最佳制备色谱条件为:正相硅胶柱(20 mm×250 mm,10～20μm),流动相:V(乙腈)∶V(甲醇)=95∶5,流速为10 mL·min-1,检测波长为215 nm,进样量为1 mL,样品浓度30 mg/mL.乙腈甲醛小分子缩合法反应原液样品的最佳制备色谱条件为:正相硅胶柱(20 mm×250 mm,10～20μm),流动相:V(乙腈)∶V(水)=90∶10,流速为10 mL·min-1,检测波长为215 nm,进样量为1 mL,样品浓度30 mg/mL.制备得到的中间体经HPLC分析知纯度均在97%以上,可直接作为结构鉴定的标准样品.     

四氮杂大环四烯镍(Ⅱ)配合物[Ni(TIM)]X催化BrO_3~-氧化双有机底物的振荡反应

本文报道了四氮杂大环四烯镍(Ⅱ)配合物[Ni(TIM)]X[TIM为2,3,9,10-四甲基-1,4,8,11-四氮杂环十四-1,3,8,10-四烯;X=(ClO_4)_2,ZnCl_4,(SCN)_2]催化BrO_3~-CH_2(CO_2H)_2-(CO_2H)_2-H_2SO_4体系的新型振荡化学反应.对该振荡反应体系进行了多方面的研究,并提出了简要的机理.     

NiL(ClO4)2催化NaBrO3-MA-H3PO4体系振荡反应的研究

报道了一种反式Curtis环的镍(Ⅱ) 的配合物NiL(ClO4)2(L为2,4,4,9,11,11-六甲基-1,5,8,12-四氮杂环十四-1,5,8,12-四烯)催化NaBrO3-CH2（COOH）2（MA）-H3PO4体系的化学振荡反应。测得该体系的振荡范围,研究、分析了各物种浓度、自由基抑制剂和还原剂、Ag+、Hg2+以及温度对振荡反应的影响。结果表明Br-起重要动力学控制作用,在反应过程中有自由基、Br2产生并参与了反应。同时发现搅拌速度对反应有很大影响。该反应的振荡轨迹与经典BZ反应及其它四氮杂大环配合物催化的体系有所不同。     

11,12,13-三甲基-1,4,7,10-四氮杂十三环-10,13-二烯-镍(Ⅱ)配合物催化的新型振荡化学反应

本文报道了一种新型振荡化学反应体系—BrO_3~--MA-H_2SO_4-[Ni(L-H)]X(X为配阴离子)体系,其中MA为丙二酸,L代表题给大环11,12,13-三甲基-1,4,7,10-四氮杂十三环-10,13-二烯.测得了该体系发生振荡的组分浓度范围;研究了各物种浓度、自由基抑制剂和还原剂对振荡反应的影响;还测得了振荡的轨迹为螺旋线而非极限环,由于催化剂消耗振荡衰减;初步提出了振荡反应发生的可能机理.     

HTEMPO和TMPD调控下MMA可控/活性光聚合研究

以HTEMPO(2,2,6,6-四甲基-4-羟基哌啶-1-氧自由基)和TMPD(2,2,6,6-四甲基哌啶酮)为调控介质, 以Irgacure 651为引发剂, 研究了甲基丙烯酸甲酯(MMA)光聚合体系的控制反应动力学, 比较了单分子(HTEMPO为调控介质)和双分子(HTEMPO和TMPD为调控介质)调控体系, 并讨论了HTEMPO和HTEMPO/TMPD在MMA光聚合体系中的调控作用、 光敏化作用和原位光氧化反应. 结果表明, 对MMA光聚合体系, 以HTEMPO/TMPD为控制介质的双分子调控体系是有效的, 获得了良好的ln(\[M0\]/\[M\])与时间, 数均分子量与转化率之间的线性动力学关系, 并且PMMA均聚物的多分散性指数(PDI)随着转化率的提高而减小. 在高转化率(>85%)下, 体系的多分散性指数(PDI)最小值可达到1.2.     

Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Simultaneous propane dehydrogenation andco2hydrogenation overCrOx/SiO2catalyst

Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO₂(DH-CO₂) reactions in the presence and absence of the CrO_x/SiO₂ catalyst have been studied between 673 and 873 K. It was found that the CrO_x/SiO₂ catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the dehydrogenation of propane to propene in the presence of CO₂on CrO_x/SiO₂can be facilitated by the RWGS reaction.</o:p>     

Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes

Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/₂, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of⁹⁹Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/₃, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material.     

Direct synthesis of dimethyl carbonate ?from CH3OH AND CO2 by H3PW12O40/CexTi1-xO2 catalyst

Summary Ce_xTi_1-xO₂ and H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ showed a better catalytic performance than the corresponding Ce_xTi_1-xO₂, due to the bifunctional catalysis of Br?nsted acid sites (provided by H₃PW₁₂O₄₀) and base sites (provided by Ce_xTi_1-xO₂). H₃PW₁₂O₄₀/Ce_0.1Ti_0.9O₂ showed the highest catalytic performance among the H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts.     

An investigation of the promotional effect of propylene or propane traces on the activity of sulfatedPt/g-Al2O3andPt-Sn/g-Al2O3inCH4combustion

Summary A strong promoting effect of the presence of C₃H₈or C₃H₆was determined for the combustion of CH₄in excess oxygen, over pre-sulfated 1%Pt/g-Al₂O₃and pre-sulfated 1%Pt-2%Sn/g-Al₂O₃catalysts.</o:p>     

Crystal structure of Na3PO4 · 12H2O

The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is $\text{C2}\text{c}$ and a unit cell contains eight formula units. The unit cell dimensions of $\text{Na}{}_3\text{PO}{}_4\text{·}\text{1}\text{2}\text{H}{}_2\text{O}$ are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO₆ octahedra. The hydrogen bonding scheme is given.     

LixNi0.8-yCo0.2ZnyOp的合成及电化学性能研究

A series of single-phase Li_xNi_0.8-yCo_0.2Zn_yO_p(0.96 ≤x≤ 1.10， 0 ≤y≤ 0.05， 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method， in which LiOH·H₂O， Zn-doped spherical Ni(OH)₂ and Co₂O₃ were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD， SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine， narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity， but also a better cycling stability characterization than the un-doped one. The Li_1.06Ni_0.75Co_0.22Zn_0.03O_2.03 material has an initial reversible capacity as high as 160.5mAh·g^-1; and a first discharge efficiency 89.2%， and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles.     

Visible light-sensitive yellow TiO2−xNx and Fe-N co-doped Ti1−yFeyO2−xNx anatase photocatalysts

Nitrogen substituted yellow colored anatase TiO_2−xN_x and Fe-N co-doped Ti_1−yFe_yO_2−xN_x have been easily synthesized by novel hydrazine method. White anatase TiO_2−δ and N/Fe-N-doped samples are semiconducting and the presence of ESR signals at g ∼1.994-2.0025 supports the oxygen vacancy and g∼4.3 indicates Fe³⁺ in the lattice. TiO_2−xN_x has higher conductivity than TiO_2−x and Fe/Fe-N-doped anatase and the UV absorption edge of white TiO_2−x extends in the visible region in N, Fe and Fe-N co-doped TiO₂, which show, respectively, two band gaps at ∼3.25/2.63, ∼3.31/2.44 and 2.8/2.44 eV. An activation energy of ∼1.8 eV is observed in Arrhenius log resistivity vs. 1/T plots for all samples. All TiO₂ and Fe-doped TiO₂ show low 2-propanol photodegradation activity but have significant NO photodestruction capability, both in UV and visible regions, while standard Degussa P-25 is incapable in destroying NO in the visible region The mid-gap levels that these N and Fe-N-doped TiO₂ consist may cause this discrepancy in their photocatalytic activities.     

Synthesis and characterization of Ti1−2xNbxNixO2−x/2 solid solutions

Doped-rutile has been traditionally used in ceramic pigments for its intense optical properties. In this paper, we compare the classical ceramic synthesis of Ti_1−2xNb_xNi_xO_2−x/2 system with the sol-gel methodology, which allows a reduction of the anatase-rutile transformation temperature. The composition was optimised in order to obtain a unique rutile phase with the minimum amount of pollutant Ni(II) and enhanced chromatic coordinates. Incorporation of the doping ions in the rutile structure was corroborated by XRD and Rietveld refinements. The species responsible for the colour mechanism were studied by different techniques. UV-VIS spectroscopy showed the characteristic features of Ni²⁺ ions, whose existence was corroborated by EPR and magnetic measurements. From these results, (Ni,Nb)doped-TiO₂ powder samples can be now shaped as thin films, monoliths, etc. by using sol-gel methodology without modifying their properties. This study introduces new possibilities of coloured TiO₂-based solid solutions in new combined advanced applications (colouring agent and photocatalyst, etc.).     

Carbon black and propylene oxidation over Ru/CoxMgyAl2Oz catalysts

The effects of Co_xMg_yAl₂O_z mixed oxides composition and ruthenium addition on the oxidation of propylene and carbon black (CB) were investigated. Different reactive cobalt and ruthenium oxide species were formed following calcination at 600 °C. The addition of ruthenium was beneficial for the CB oxidation under “loose contact” conditions and for propylene oxidation when the cobalt content was intermediate to low. The calculated activation energy for CB oxidation was decreased from 151 kJ mol⁻¹ for the uncatalyzed reaction to 111 kJ mol⁻¹ over the best catalyst.