Pd/C气体扩散电极电化学降解4-氯酚的比较研究

分别采用氢气还原法和甲醛还原法制备了Pd/C催化剂, 利用XRD、TEM及XPS对催化剂进行了表征, 并由催化剂制备成Pd/C气体扩散阴极, 采用先通氢气后通空气的方式在隔膜电解体系中对4-氯酚进行降解, 比较了不同电极体系下4-氯酚的去除效果. 结果表明, 制备的Pd/C气体扩散阴极既对4-氯酚具有还原脱氯作用(通入H₂时), 又能够促进O₂还原生成H₂O₂(通入O₂时), 它们对4-氯酚的去除效果要好于不掺杂Pd的气体扩散阴极. 使用氢气还原法制备出的Pd/C催化剂中Pd表面的活性点比甲醛还原法制备出的要多, 电极稳定性好, 反应60 min后 4-氯酚转化率和脱氯率接近100%, 120 min后阴极室COD去除率为87.4%.     

氨基修饰Pd/TiO_2/C复合催化剂的制备及在碱性溶液中对乙醇的催化氧化性能

以钛酸四丁酯为前驱体,采用水热法合成二氧化钛纳米片(TiO2),通过3-氨基丙基-三甲氧基硅烷(APTMS)分子对TiO2表面进行氨基修饰后,将其与Vulcan XC-72活性炭复合作为载体,吸附钯前驱体后,再进行液相还原制得Pd/TiO2/C-APTMS复合催化剂.用透射电子显微镜(TEM)、X射线能量色散谱(EDS)、电感耦合等离子体原子发射光谱(ICP-AES)、X射线衍射谱(XRD)和X射线光电子能谱(XPS)表征了催化剂的形貌、组成和结构.电化学测试结果表明,与传统液相混合还原制备的Pd/TiO2/C复合催化剂和Pd/C相比,经氨基修饰后的Pd/TiO2/C-APTMS复合催化剂在碱性溶液中对乙醇氧化具有更高的电催化活性和稳定性.     

5(6)-氨基-1-(4-氨基苯基)-1,3,3-三甲基茚满合成及工艺优化

以5(6)-硝基-1-(4-硝基苯基)-1,3,3-三甲基茚满为原料,Pd/C为催化剂,用氢气还原合成5(6)-氨基-1-(4-氨基苯基)-1,3,3-三甲基茚满。红外、核磁表征了产物结构;考察了反应温度、反应时间、充入氢气压力及催化剂用量四个因素,设计正交试验对还原工艺条件进行优化分析。结果表明,对粗产率的影响显著程度依次为充入H2压力、反应时间、反应温度和催化剂用量,获得了优化工艺条件,即反应温度70℃、反应时间为2 h、充入H2压力为1.5 MPa,催化剂用量为5(6)-硝基-1-(4-硝基苯基)-1,3,3-三甲基茚满的10%。     

2-硝基-10-羟基-5,10-二氢磷杂吖嗪-10-氧化物的还原研究

10-羟基-5,10-二氢磷杂吖嗪-10-氧化物硝基衍生物的还原反应研究报道始见于1978年.尹志刚等进一步对2-硝基-10-羟基-5,10-二氢磷杂吖嗪-10-氧化物进行了催化加氢研究,结果发现,催化剂用量达到底物质量的7.5%以上,反应介质为中性或弱碱性,该化合物能够被顺利还原[1].该还原方法缺点是Pd/C催化剂不能够回收利用,还原成本高,需要较高氢气压力,危险性大,从而不利于该染料中间体工业化生产.     

Pd/C催化下汉斯酯1,4-二氢吡啶还原芳香叠氮化合物、芳香硝基 化合物以及碳碳双键的反应研究

汉斯酯1,4-二氢吡啶(HEH)在Pd/C催化下可以将取代的芳香叠氮化合物还原为相应的取代苯胺, 反应具有很好的选择性. 该方法也可以用于芳香硝基化合物的还原. 对于Pd/C催化下汉斯酯1,4-二氢吡啶还原碳碳双键的可行性, 论文中也进行了初步的探讨.     

啶酰菌胺的合成研究

本文报道一种啶酰菌胺的新方法,即用Pd(OH)2/C催化的对氯苯硼酸与2-硝基溴苯的Suzuki反应、其产物2-(4-氯苯基)硝基苯经水合肼-三氯化铁体系还原后与2-氯烟酰氯或2-氯烟酸缩合得目标产物。在Suzuki反应中,考察了反应温度、无机碱、季铵盐和溶剂对反应的影响后。再考虑到生产效率与生产成本的因素,发现以K3PO4·7H2O为无机碱,四丁基溴化铵(TBAB)为助剂,在DMF中,120℃下反应13h,Pd(OH)2/C能很好地催化对氯苯硼酸与2-硝基溴苯的Suzuki反应,并在这一的条件下考察Pd(OH)2/C循环利用的情况。     

Pd/C催化剂用于CO2电化学还原生成CO:Pd载量的影响

CO₂电化学还原反应可以将CO₂转化为燃料并同时实现再生能源的有效存储. 目前纳米结构的多相催化剂已经广泛应用于此反应,其中碳负载钯纳米粒子（Pd/C）表现出优异的CO₂电化学还原性能. 本工作研究了钯载量对于Pd/C催化剂结构以及其催化CO₂还原生成CO反应活性和选择性的影响. 不同载量的Pd/C催化剂通过液相还原方法制备,钯纳米粒子均匀地分散在碳载体上,载量并没有明显改变对纳米粒子的粒径. 在优选的电解质（0.1 mol·L^-1 KHCO₃）中,CO法拉第效率与载量呈现火山型曲线关系,-0.89 V时载量为20wt%的Pd/C催化剂达到最高的CO法拉第效率(91.2%). 生成CO的几何电流密度随着钯载量的增加而增加,但CO转换频率具有相反的趋势,载量为2.5wt%的Pd/C催化剂具有最高的转换频率. 这种载量对CO₂电化学还原反应活性和选择性的影响主要由活性位的数量、反应动力学、中间物种的稳定性以及反应物、中间物种和产物的传质过程等共同决定.     

3-氨基-1,3,4,5-四氢-2H-1-苯并氮杂革-2-酮的合成

以3-溴-1,3,4,5-四氢-2H-1-苯并氮杂--2-酮为起始原料,与苄胺反应制得3-苄氨基-1,3,4,5-四氢-2H-1-苯并氮杂(堇)-2-酮(2);2经5％ Pd/C催化加氢合成了3-氨基-1,3,4,5-四氢-2H-1-苯并氮杂——革)-2-酮(3),总收率90％.最佳氢化反应条件为:以无水乙醇为溶剂,5％ Pd/C用量为总用量的10％,于100℃/2.5 MPa条件下反应10 h,3的收率95.5％,纯度99.7％.5％ Pd/C可套用7次,收率稳定在95％左右.     

1-甲基-3-丙基-4-氨基吡唑-5-甲腈的研究

以1-甲基-3-丙基吡唑-5-甲酸为原料,经酰化、脱水、硝化、还原反应合成了1-甲基-3-丙基-4-氨基吡唑-5-甲腈,然后与醛类缩合得到吡唑并嘧啶酮衍生物.在Pd/C催化氢化1-甲基-3-丙基-4-硝基吡唑-5-甲腈的过程中,利用HPLC和HPLC-HRMS分离检测到硝基还原为氨基过程的3个中间体:羟胺、氧化偶氮、偶氮化合物,提出了可能的还原机理.产物结构经~1H NMR,~(13)C NMR,IR和MS分析表征.     

炭载Pd-Fe合金催化剂的制备及电催化氧还原活性

研究了用NH4Cl作配位剂的配位还原法来制备的Pd-Fe/C催化剂,发现由于NH4Cl能与Pd形成配合物,使Pd Cl2的还原电位负移,与Fe Cl3的还原电位接近,从而在低温下制备得到了高合金化程度的Pd-Fe/C催化剂。XPS表征结果表明:Pd与Fe形成合金后,Pd的电荷密度的减少,增加了Pd0的含量。因此,得到的Pd-Fe/C催化剂对氧还原的电催化活性比用相同方法制得的Pd/C催化剂高,而且该催化剂对甲醇氧化没有电催化活性。     

An efficient and facile one-pot synthesis of structurally unique 2,4,6-tris(arylchalcogeno)-1,3,5-triazine and 1,3,5-tris(arylchalcogeno)-2,4,6-trimethylbenzene

An efficient one-pot synthesis of a novel class of 2,4,6-tris(arylchalcogeno)-1,3,5-triazine (sulfur, selenium and tellurium) and 1,3,5-tris(arylchalcogeno)-2,4,6-trimethylbenzene (sulfur and selenium)-containing ligands has been developed based on the reaction of 2,4,6-trichloro-1,3,5-triazine and 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene with the corresponding arylchalcogenide anions generated in aqueous tetrahydrofuran.     

Synthesis and photophysical properties of hyperbranched polyfluorenes containing 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine as the core

A series of new hyperbranched polymers containing a 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine core unit and polyfluorene chain arms have been synthesized via Suzuki coupling, and characterized by NMR, IR and GPC. All the polymers exhibit good thermal stability with a high decomposition temperature. By changing the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine/fluorene ratio the UV-vis absorption and emission spectra can be partially tuned. It has been found that the polymers containing a low ratio of 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine units (P1-P3) have an absorption maximum around 385 nm, localized in the polyfluorene chain, and a shoulder around 425 nm ascribable to a charge transfer state involving the fluorene and the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine core. Increasing the molar ratio of the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine unit enhances the charge transfer band which becomes dominant for P4. The LUMO level of these polymers is relatively low due to the electron affinity of the triazine group. The polymers show dual emission, with a structured band in the blue (410-440 nm), attributed to the polyfluorene, and a broad band in the red (470-500 nm) associated with the charge transfer state. All the polymers exhibit two-photon absorption activity in the range of 660 to 900 nm with the maximum two-photon absorption (TPA) cross-section red-shifted from the corresponding linear absorption. The values of the TPA cross-sections vary from 1000 to 5000 GM, following the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine/fluorene ratio.     

Heterogeneous photocatalytic transformations of s-triazine derivatives

Photocatalytic processes arising from irradiated semiconductor oxide suspensions containing 1,3,5-triazine (s-triazine) derivatives are described. Whereas unsubstituted 1,3,5-triazine undergoes hydrolysis, irrespective of the presence of the photocatalyst, other chloro-, amino-, mercapto-, allyloxo-, carboxy- derivatives give rise, in the presence of band-gap excited semiconductor oxide, to nearly stoichiometric formation of 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid). This last compound is stable toward photocatalytic conditions as well as to ^·OH chemically generated in homogeneous solution (H₂O₂/UV or Fenton's reagent). Only partial conversion in cyanuric acid is observed for 2,4,6-tris(2-pyridyl)-1,3,5-triazine and possible explanation is given. The formation of inorganic species (nitrate, chloride, sulfate and ammonium ions) is reported and the mechanism of their evolution presented.     

Synthesis, characterization, and dynamic DSC curing kinetics of novel epoxy resin of 2,4,6-tris(4-hydroxyphenyl)-1-3-5-triazine

2,4,6-Tris(4-hydroxyphenyl)-1,3,5-triazine was synthesized by cyclotrimerization of 4-cyanophenol using trifluromethanesulphonic acid as a catalyst at room temperature. 2,4,6-Tris(4-hydroxyphenyl)-1,3,5-triazine was epoxidized using alkali as a catalyst at 60 °C for 1 h. Epoxy resin was cured by DSC at multiple heating rates under nitrogen atmosphere by using 20 % of 4,4′-diamino diphenylsulphone, 4,4′-diaminodiphenylether, and 4,4′-diaminodiphenylcyclohexane as hardeners. Cured and uncured reins were also analyzed by TG analysis. Kinetic parameters were determined and discussed in light of nature of curing agents. Thermal decomposition behavior of the samples is also discussed in detail.     

Thermodynamic stability of 2,4,6-tris(nitromethyl)-1,3,5-triazine: an experimental and theoretical study

The molecular geometries and electronic structures of 2,4,6-tris(nitromethyl)-1,3,5-triazine isomers were investigated by the density functional method DFT/B3LYP/6-311++G** to elucidate the structural factors responsible for the stability of these systems. It was shown that a characteristic feature of the nitromethyl tautomer (1) of 2,4,6-tris (nitromethyl)-1,3,5-triazine consists in nonvalence interactions between an oxygen atom of nitro group and a carbon atom of triazine ring, which are probably due to Coulomb attraction between them. The tautomer with the 2,4,6-tris (nitromethylene)-hexahyrdo-1,3,5-triazine structure (2) is stabilized trough direct polar conjugation between the amino and nitro groups at the double bond. Structural strain of the molecule with the 2,4,6-tris(aci-nitromethyl)-1,3,5-triazine structure (3) is the reason for its thermodynamic instability. X-ray data indicate that the compound under study exists in the triazine tautomeric form 1 and the distances between oxygen atoms of nitro group and carbon atom of the triazine ring are shortened. NMR data suggest the existence of triazine in the nitromethyl form 1 in acetonitrile and acetone and a tautomeric equilibrium between the nitromethyl and nitromethylene forms in a more polar solvent (DMSO). The results obtained suggest a Coulomb-type stabilization of the 2,4,6-tris(nitromethyl)-1,3,5-triazine molecule in the gas phase, in the crystal, and in nonpolar solvents.     

Chemical Graft of Cellulose with the Ion-Pair Emulsion Containing the Reactive Groups and Its Dyeing Properties

Chemical graft of cellulose with ion-pair disperse emulsion containing the reactive groups was investigated. The ion-pair disperse systems were consisted of a 1,3,5-triazine derivative containing the reactive groups, 2,4,6-tri[(2-hydroxy-3-trimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-HTAC) and 2,4,-bichloro[(6-sulfanilic acid)-1,3,5-triazine (Bi-CSAT). Compared with unmodified cellulose, the modified cotton exhibited different behavior towards dyeing. The modified cotton could be dyed with reactive dyes without the addition of salt. The color yield was higher than that on untreated cotton, despite of the addition of large amounts of salt in the latter case. Cotton fabric modified with ion-pair disperse emulsion was imparted good level dyeing properties. The dyeing rate was slower in the presence of the ion-pair compounds than that in the present of the only cationic compounds.     

Reaction of 2,4,6-triazido-1,3,5-triazine with triphenylphosphane. syntheses and characterization of the novel 2-triphenylphosphanimino-4-azidotetrazolo[5,1-a]-[1,3,5]triazine and 2,4,6,-tris(triphenylphosphanimino)-1,3,5-triazine

2-Triphenylphosphanimino-4-azidotetrazolo[5,1-a]-[1,3,5]triazine (6) was obtained by reaction of 2,4,6-triazido-1,3,5-triazine (1) with 1 equiv of triphenylphosphane. Raman and X-ray data revealed that only one azide group formed a tetrazole ring system whereas the second azide group did not undergo ring closure. To investigate the equilibrium between the tetrazole isomer and the open-chain azide structure for these and related species, (31)P NMR studies were carried out. The obtained spectra displayed an equilibrium between the tetrazole and the open-chain azide isomers. 2,4,6-Tris(triphenylphosphanimino)-1,3,5-triazine (4) was prepared by treatment of 1 with 3 equiv of triphenylphosphane, and its X-ray structure is discussed. On the basis of PM3 semiempirical and density functional calculations, the reaction of 1 with triphenylphosphane was studied. The thermodynamics of different isomerization reactions and the activation barriers to cyclization were estimated.     

High-pressure bulk synthesis of crystalline C(6)N(9)H(3).HCl: a novel c(3)n(4) graphitic derivative

A novel carbon nitride compound, structurally related to the proposed graphitic phase of C(3)N(4), has been synthesized in a bulk well-crystallized form. The new material, with stoichiometry C(6)N(9)H(4)Cl, was prepared through a solid-state reaction of 2,4,6-triamino-1,3,5-triazine with 2,4,6-trichloro-1,3,5-triazine at 1.0-1.5 GPa and 500-550 degrees C and also through a self-reaction of 2-amino-4,6-dichloro-1,3,5-triazine at similar conditions. X-ray and electron diffraction measurements on the yellowish compound indicate a hexagonal space group (P6(3)/m) with cell parameters of a = 8.4379(10) A and c = 6.4296(2) A. This new compound possesses a two-dimensional C(6)N(9)H(3) framework that is structurally related to the hypothetical P6m2 graphitic phase of C(3)N(4), but with an ordered arrangement of C(3)N(3) voids. The large voids in the graphene sheets are occupied by chloride ions with an equivalent number of nitrogen atoms on the framework protonated for charge balance. The composition of the sample was determined by bulk chemical analysis and confirmed by electron energy loss (EELS) spectroscopy. The chemical and structural model is consistent with bulk density measurements and with the infrared and (13)C NMR spectra. This work represents the first bulk synthesis of a well-characterized and highly crystalline material containing a continuous network of alternating carbon and nitrogen atoms.     

Multicomponent Molecular Systems Based on Porphyrins, 1,3,5-Triazine and Carboranes: Synthesis and Characterization

2,4,6-Trichloro-1,3,5-triazine (cyanuric chloride) is an excellent coupling reagent for the preparation of highly structured multifunctional molecules. Three component systems based on porphyrin, cyanuric chloride and carborane clusters were prepared by a one-pot stepwise amination of cyanuric chloride with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin, followed by replacement of the remaining chlorine atoms with carborane S- or N-nucleophiles. Some variants of 1,3,5-triazine derivatives containing porphyrin, carborane and residues of biologically active compounds such as maleimide, glycine methyl ester as well as thioglycolic acid, mercaptoethanol and hexafluoroisopropanol were also prepared. A careful control of the reaction temperature during the substitution reactions will allow the synthesis of desired compounds in a good to high yields. The structures of synthesized compounds were determined with UV-vis, IR, ¹H NMR, ¹¹B NMR, MALDI-TOF or LC-MS spectroscopic data. The dark and photocytotoxicity as well as intracellular localization and photoinduced cell death for compounds 8, 9, 17, 18 and 24 were evaluated.     

Trisubstituted 1,3,5-triazines. 2. Synthesis of 1,3,5-triazines from 2,4,6-tris[di(tert-butoxycarbonyl)methylene]hexahydro-1,3,5-triazine

A study was carried out on electrophilic addition and hydrolytic dissociation of 2,4,6-tris[di(tert-butoxycarbonyl)methylene]hexahydro-1,3,5-triazine. Chloro, bromo, and methyl derivatives of tris[di(tert-butoxycarbonyl)methyl]-1,3,5-triazine were synthesized for the first time as well as 2,4,6-tris-(tert-butoxycarbonylmethyl)-1,3,5-triazine. For Communication 1, see ref. [1]. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow and Institute of Chemical Physics, Russian Academy of Sciences at Chernogolovka, 142432 Chernogolovka, Moscow Oblast. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1404–1407, October, 1998.