Liquid-phase hydrodechlorination of polychloroaromatic compounds in the presence of Pd-promoted nickel catalysts

Liquid phase hydrodechlorination of chlorobenzene, 1,2,4-trichlorobenzene, hexachlorobenzene, polychlorinated biphenyls in the ethanol-containing solution, on Me⁰/C (where Me⁰-Pd, Ni or bimetallic Ni−Pd; C-carbon material “Sibunit”) with H₂ have been studied at 20–70°C and P_{H 2}=1–50 atm. Pd and Pd-promoted Ni catalysts exhibit the highest activity. Kinetic studies show hydrodechlorination of these compounds to be a consecutive reaction, which under the conditions described may produce less chlorinated compounds.     

Pd‐Pt/modified GO as an efficient and selective heterogeneous catalyst for the reduction of nitroaromatic compounds to amino aromatic compounds by the hydrogen source

In this work, different nitroaromatic compounds were successfully reduced to their corresponding aromatic amines with excellent conversion and selectivity in methanol at 50 °C by using Pd‐Pt nanoparticles immobilized on the modified grapheme oxide (m‐GO) and hydrogen as the reducing source. The catalytic efficiency of Pd and Pd‐Pt loading on the modified GO was investigated for the reduction of various nitroaromatic compounds, and the Pd‐Pt/m‐GO system demonstrated the highest conversion and selectivity. The catalyst was characterized by different techniques including FT‐IR, Raman, UV–Vis, XRD, BET, XPS, FESEM, EDS, and TEM. The metal nanoparticles with the size of less than 10 nm were uniformly distributed on the m‐GO. The catalyst could be reused at least five times without losing activity, showing the stability of the catalyst structure. Finally, the efficiency of the prepared catalyst was compared with Pd‐Pt/AC, and Pd‐Pt/GO catalysts.     

Enantioselective hydrogenation of isophorone over Pd catalysts in the presence of(−)-dihydroapovincaminic acid ethyl ester: The effect of reduction method of Pd blacks on the enantiomeric excess

The enantioselective heterogeneous catalytic hydrogenation of isophorone in the presence of apovincaminic acid ethyl ester was investigated. Various Pd black catalysts differing in their preparation method were studied. The catalysts were characterized by different methods such as physical adsorption and chemisorption, SEM and XPS. An explanation was created for the different enantioselectivity of the catalysts being precipitated by different reducing agents.     

Adsorption of methane and ethane, 1. Studies of work function changes of Pt foil. Effect of pressure

Liquid-phase hydrogenation of 3-thiolene-1,1-dioxide to thiolane-1,1-dioxide on Pd catalysts has been studied. According to the kinetic and adsorption data, at 20°C and P_{H 2}=0.1–1.0 MPa the reaction proceedsvia the interaction of adsorbed 3-thiolene-1,1-dioxide with dissolved H₂. At P_{H 2}=2–7 MPa, the reaction between the adsorbed H₂ and dissolved 3-thiolene-1,1-dioxide is the limiting step of the process.     

Pd/C和Raney Ni催化剂的制备及其催化活性比较

制备了Pd/C和Raney Ni催化剂,其结构和性能经XRD,BET和SEM表征。并以呋喃加氢制备四氢呋喃为探针反应,对两种催化剂的催化活性进行了比较,探讨了反应温度、反应压力和催化剂用量对转化率和选择性的影响,结果表明:Raney Ni的催化活性优于Pd/C。     

Catalytic hydrogenation of aromatic nitro compounds by non-noble metal complexes of chitosan

Silica-supported mono-metal (such as Ni, Cu) complexes and mixed metal (such as Cu/Zn, Cu/Cr) complexes of chitosan have been prepared. It is found that these non-noble metal complexes could be used as efficient catalysts for the hydrogenation of aromatic nitro compounds. The effects of type of metal, reaction temperature and pressure, solvent, nitrogen/metal molar ratio in the complex catalysts on the yields from nitrobenzene to aniline have been examined. It was also found that catalysts are active for the catalytic hydrogenation of other aromatic nitro compounds such as 2-nitroanisole, 2-nitroaniline, 2-nitrotoluene and 1-chloro-4-nitrobenzene.     

Reaction of CO2 and H2 in the presence of Co and Ni catalysts

The activity and selectivity of 10 % Co/support and 10 % Ni/support catalysts (where the support is A1₂O₃, SiO₂, C) in the synthesis of hydrocarbons from CO₂ and H₂ were studied. The extent of conversion of the starting mixture and the yield of methane were shown to depend on the composition of the catalytic system. Cobalt catalysts with various types of carbons as supports are the most active. They permit the synthesis of methane in yields up to 70 % of the theoretical value.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 482–484, March, 1993.     

肉桂醛催化选择加氢反应中双金属的协同效应

对既含有ＣＣ键又含有ＣＯ键的分子,ＣＣ键的选择加氢意义重大［１］．α,β不饱和醛选择加氢成饱和醛就属于此类．钯是已知的可在温和条件下将α,β不饱和醛选择加氢生成饱和醛最有效的催化剂之一．人们曾研究了不同钯化合物催化剂对α,β不饱和醛中ＣＣ的双键选择加...     

Intramolecular cyclization of O-(3,5-dinitrophenyl) and O-(3-amino-5-nitrophenyl) ketoximes, products of transformations of 1,3,5-trinitrobenzene. The synthesis of nitrobenzo[b]furans and 4-hydroxynitroindoles

O-(3,5-Dinitrophenyl) ketoximes obtained in the reactions of ketoximes with 1,3,5-trinitrobenzene undergo acid-catalyzed cyclization into 2-substituted or 2,3-disubstituted 4,6-dinitrobenzo[b]furans. In analogous cyclization, products of selective reduction of a nitro group in O-(3,5-dinitrophenyl) ketoximes unexpectedly yield, along with 6-amino-4-nitrobenzofurans, 4-hydroxy-6-nitroindoles. The 4-NO₂ group is displaced from 4,6-dinitrobenzo[b]furans in reactions with thiols in the presence of K₂CO₃. Conditions for nitration and sulfochlorination of 4,6-dinitrobenzo[b]furans in position 3 were found. Condensation of a 2-methyl derivative with dimethylformamide acetal was accomplished. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 984–991, May, 2007.     

Mild and efficient deprotection of allyl ethers of phenols and hydroxycoumarins using a palladium on charcoal catalyst and ammonium formate

An efficient procedure for the cleavage of allyl phenyl ethers and allyl coumarinyl ethers using a catalytic amount of 10% Pd/C in combination with ammonium formate is described. Allyl ethers of phenols are deprotected in preference to those of alcohols and this method is compatible with several reducible functional groups such as CHO, COCH₃, CO₂Et and NHCOCH₃.     

四氯化碳液相催化加氢制氯仿多元金属催化剂的制备及其催化性能

以贵金属M(=Pd,Pt)为主要活性成分,掺加过渡金属Fe和Ni作为助剂,采取浸渍和氢气还原法制备了椰壳活性炭(ACcs)负载的单元金属(M/ACcs)、二元金属(M-Ni/ACcs、M-Fe/ACcs)和三元金属(M-Ni-Fe/ACcs)系列催化剂;通过CC_l4液相催化加氢制氯仿反应考察了这些催化剂的催化活性和选择性。结果表明,Pd基催化剂的催化活性明显高于Pt基催化剂,但后者对氯仿的选择性优于前者;在前5 h加氢反应时段,两系列催化剂的活性顺序为:Pd-Ni-Fe/ACcsPd-Fe/ACcsPd/ACcsPd-Ni/ACcs和Pt/ACcs≈Pt-Fe/ACcsPt-Ni/ACcsPt-Ni-Fe/ACcs;总体上,引入Fe对于催化性能的改善效果要优于Ni,Ni的单独引入则会不同程度地降低催化活性。综合考量成本、活性和选择性等因素,优选Pd-Ni-Fe/ACcs作为催化剂,在393 K下反应5 h,可实现CC_l497.6%的转化率以及接近100%氯仿的选择性。     

Catalytic dechlorination of aromatic chloride with supported palladium catalysts in alkaline 2-propanol: influence of hydrocarbon solvents

Summary Catalytic dechlorination of p-chloroanisole (p-chloromethoxybenzene) was carried out in a solution of NaOH in 2-propanol in the presence of Pd/Al₂O₃ or Pd/C at 40°C. When aromatic hydrocarbons such as toluene or benzene were added to the solution, the dechlorination rates were strongly suppressed. However, aliphatic hydrocarbons such as n-hexane or cyclohexane hardly affected the dechlorination rates.     

Interaction of polynitro compounds with difluoroamine

Difluoroamine does not react with tetranitromethane and fluoro-, chloro-, and bromotrinitromethanes in DMF and in acidic media (CF₃COOH, ClSO₃H, FSO₃H, and oleum), but reacts with α-fluoro- and α-(difluoroamino)-α,α-dinitrotoluenes to give substitution products of the difluoroamino group for both the nitro groups,viz., PhC(NF₂)₂F and PhC(NF₂)₃, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1647–1649, August, 1998.     

Influence of the ZSM-5 Support Acidity on the Catalytic Performance of Pd/ZSM-5 in Lean Methane Oxidation

Although zeolites are characterized by their special acidic properties, there is still no clear consensus on the effect of zeolite support acidity on the catalytic activity of supported Pd catalyst in methane oxidation. Herein, a series of Pd/H-ZSM-5 and Pd/Silicalite-1 catalysts was prepared by the deposition-precipitation method and used in lean methane oxidation. The effect of ZSM-5 support acidity on the catalytic performance of Pd/ZSM-5 was investigated. The results indicate that with the decrease of Si/Al ratio(x), viz., the increase of acid sites in H-ZSM-5(x), the catalytic activity of Pd/H-ZSM-5(x) increases substantially; the activity of various catalysts in the lean methane oxidation decreases in the order of Pd/H-ZSM-5(28)>Pd/H-ZSM-5(48)>Pd/H-ZSM-5(88)>Pd/H-ZSM-5(204)>Pd/Silicalite-1. Furthermore, various characterization measures reveal that the catalytic activity of Pd/H-ZSM-5(x) in lean methane oxidation is mainly related to the Lewis acid sites in the H-ZSM-5 support, whereas less relevant to the Brønsted acid sites. The abundant Lewis acid sites in H-ZSM-5 are capable to enhance the interaction between the Pd species and H-ZSM-5 support, which can inhibit the agglomeration of Pd particles and improve the dispersion of Pd species, and thus boost the catalytic activity of Pd/H-ZSM-5 in methane oxidation.     

Catalytic properties of Cu-Co catalysts supported on HNO3-pretreated CNTs for higher-alcohol synthesis

HNO 3 -pretreated CNTs were employed as supports, and a special ultrasound-assisted impregnation method was designed to prepare supported Cu-Co catalysts for higher-alcohol synthesis from syngas. The catalysts used in this work were characterized by N 2 adsorption-desorption, TEM, XRD, H 2 -TPR, CO-TPD techniques. It was found that the pre-treatment procedure of CNTs remarkably promoted the catalytic properties of the Cu-Co/CNTs catalysts. For the Cu-Co catalyst supported on CNTs pre-treated by 68 wt% HNO 3 , some active components were introduced into the CNTs channels, their dispersions and the amount of strongly adsorbed CO-species were improved. The CO conversion and alcohol yield on the HNO 3 -pretreated Cu-Co/CNTs catalyst were increased by ～21% and ～69%, respectively, compared with those on the normal Cu-Co/CNTs catalyst.     

磷酸铈对磷化镍催化苯酚转移加氢的促进作用

通过氢气原位程序升温还原法制备了一系列不同Ce/Ni摩尔比的CePO₄-Ni₃P及Ni₃P催化剂,考察了其在苯酚催化转移加氢反应的催化性能.研究了Ce/Ni摩尔比、供氢溶剂、反应温度和反应时间对催化剂性能的影响,并初步考察了苯酚转移加氢的反应动力学.研究结果表明,CePO₄的加入能显著提升体相Ni₃P催化苯酚转移加氢的转化率,且Ce/Ni摩尔比为0. 2时促进作用最显著;在所考察的供氢溶剂中异丙醇展现出最好的性能;使用Ce PO₄(0. 2)-Ni3P作为反应催化剂,异丙醇作为供氢溶剂,220℃下反应6 h,苯酚转化率和环己醇选择性分别可达93. 1%和92. 0%.     

Acyl and Sulfonyl Derivatives of 3,5-Diamino-1-R-1,2,4-triazoles

3-Acylamino-5-amino-1-R-1,2,4-triazoles are formed regioselectively on acylating 3,5-diamino-1-R-1,2,4-triazoles with an equimolar amount of anhydrides, carboxylic acid chlorides, and sulfonyl chlorides. With an excess of anhydride and carboxylic acid chloride 3,5-diacylamino-1-R-1,2,4-triazoles are formed. 3-Acylamino-5-amino-1-R-1,2,4-triazoles do not interact with sulfonyl chlorides. The higher reactivity of the 3-amino group towards acylating agents is determined by electronic and not steric factors. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1342–1350, September, 2005.     

Study of structural aspects of thermochemical conversions of compounds modeling oligophenylenes containing acenaphthylenyl and acenaphthenyl groups

With the aim of elucidating the mechanism of the thermochemical conversion of oligophenylenes containing acenaphthylenyl groups, the thermolysis of model compounds: l,3,5-tris(5-acenaphthylenyl)benzene (1), 1,3,5-tris(5-acenaphthenyl)benzene (2), acenaphthylene, and acenaphthene, was studied by differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA), and mass spectrometry. Compounds1 and2 were studied by X-ray structural analysis. A scheme for the formation of secondary structures was suggested. Optimum temperature conditions were found for preparing thermostable, heat-resistant, and stable to thermooxidation polymers based on compounds containing the acenaphthylenyl groups.Deceased in 1993.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 846–854, May, 1994.We thank V. M. Laktionov for performing the differential scanning calorimetric analysis.