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1.
A. Sri Hari Kumar V. N. Kalevaru A. Qiao A. Alshammari N. Lingaiah Ch. Sailu P. S. Sai Prasad A. Martin 《Kinetics and Catalysis》2013,54(5):615-619
Oxidative dehydrogenation of ethane (ODHE) to ethylene was investigated over a series of alumina supported molybdophosphoric acid (MPA) catalysts. The MPA was transformed into surface Mo oxides on Al2O3 when subjected to calcination at 600°C. The catalysts were characterized by N2-adsorption, XRD, FT-IR spectroscopy and TPR techniques. The results showed that MPA loading and the source of Mo precursor had a clear influence on the catalytic performance. The evaluation of the catalysts for ODHE at temperatures between 450 and 550°C revealed superior ethane conversion (X~24%) and ethylene selectivity (S = ca. 65%) over 20 wt % MPA/Al2O3 catalyst. The transformation of MPA into finely dispersed Mo oxides on Al2O3 appeared to be responsible for this improved performance. 相似文献
2.
For the first time, we have observed a combined effect of two bases NaOH/Et3N to promote the diazo transfer reaction of β-oximino esters. This unusual synergistic effect has been employed to obtain α-diazo oxime ethers directly from β-keto esters by one-pot process. This method is simple and cost-effective and the reagents are readily available. 相似文献
3.
Wildhaber-Novikov gears are becoming more and more popular for heavy load applications. They have been tried as speed-reducing gears, in spite of heavy noise generation, in aircraft jet engines, marine engines and agricultural machinery. These circular-arc gears, though stronger than involute geras, have the disadvantage of needing larger face width. Axial face width required can be minimized only at the expense of load-carrying capacity. This is not a serious disadvantage with stationary engines. But in the case of automotive applications, this fact limits the load-carrying capacity of Wildhaber-Novikov gears, since space problem is very critical in these applications and large face widths, therefore, cannot be used for such gear-reduction units. The face width is determined by the helix angle and, therefore, a thorough investigation of the dependence of the load-carrying capacity on helix angle is necessary, if these special types of gears have to make headway into the automotive field. In this experimental investigation, three-dimensional photoelastic technique has been employed to study the load-carrying capacity/face width ratio. Three-dimensional gear models made of epoxy castings (Araldite B) were loaded in a specially built gear-loading fixture and were stress frozen. Gear cutters of Wildhaber-Novikov gears developed at the laboratory were used for the preparation of these three-dimensional gear models. The stress-frozen models were analyzed using the conventional slicing technique to study the contact and bending-stress distribution along the face width. The load-carrying capacity in terms of contact stress and bending stress has been studied for different face widths and helix angles. Twenty-deg pressure angle, 14-mm module gears of alladdendum type of Wildhaber-Novikov gears with different helix angles up to 40 deg were tested. The helical-overlap ratio used was 1.0. The conventional profile parameters were employed for the manufacture of gear cutters of end-mill type. The decrease in contact and bending strength with increase in the helix angle or decrease in the face width, as obtained from this photoelastic method of stress analysis has been compared with existing theoretical results. 相似文献
4.
A stereoselective total synthesis of xyolide, a naturally occurring bioactive nonenolide, has been accomplished. The acid fragment of the molecule has been prepared from D ‐mannitol and the alcohol fragment from (2Z)‐but‐2‐ene‐1,4‐diol. The synthesis involves the coupling of these two fragments using the Yamaguchi esterification protocol, followed by intramolecular ring‐closing methathesis. The diastereoisomeric alcohol fragment has also been utilized in this synthesis by employing the Mitsunobu esterification. 相似文献
5.
Summary Complexes of platinum(II) with 2-(acetylamino)benzoic acid, 2-(benzoylamino)benzoic acid, maleanilic acid, malea-1-naphthanilic acid, 2-(phenylamino)benzoic acid, 2-[(2-aminophenylamino)carbonyl]benzoic acid, 2-(aminobenzoyl)benzoic acid, 2-[1-naphthalenylamino)-carbonyl]benzoic acid, 2-(2-aminobenzoylamino)-benzoic acid have been prepared and characterized by elemental analysis, molar conductivity measurements, thermal data and i.r., electronic and n.m.r. spectra. 相似文献
6.
Complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Pd(II) with di-N-phenyl pyromellitic diimide (PhPMDI) and di-N-pyridyl
pyromellitic diimide (PyPMDI) were prepared and characterized based on analytical, molar conductance, magnetic, IR, PMR, electronic
and ESR data. Based on analytical and molar conductance, the complexes have been formulated as [M(PhPMDA)(H2O)2]n (M = Mn, Fe, Co, Ni), [Cu(PhPMDA)]n [Pd2(PhPMDA)Cl2(H2O)2], [M(PyPMDA)]n (M = Mn, Fe, Co, Ni and Cu) and [Pd2(PyPMDA)Cl2] In all these complexes PhPMDA acts as a mononegative bidentate ligand whereas PyPMDA acts as a mononegative tridentate one
in the form of amide rather than imide. The geometries of the complexes have been proposed based on the electronic spectra.
The various bonding parameters have been calculated from the ESR spectra of Cu(II) complexes. 相似文献
7.
N. Lingaiah N. Seshu Babu Rajesh Gopinath P. Siva Sankara Reddy P. S. Sai Prasad 《Catalysis Surveys from Asia》2006,10(1):29-39
The use of supported Pd catalysts, with low and high metal content, for the hydrodechlorination of chlorobenzene is presented in this article. Application of microwave irradiation during preparation of catalysts resulted in the synthesis of large Pd particles at moderate temperatures. The nature of the support played a key role in the formation of cationic Pd species. The extent of interaction of the Pd species with the support, the nature of metal precursor, particularly the residual chlorine on the surface were found to significantly affect the activity of the catalysts. In the case of bimetallic catalysts also microwave heating resulted in creation of bigger particles of Pd compared to those observed in conventionally heated catalysts. Besides, it minimized alloy formation as a result of which the activity of the catalysts in hydrodechlorination was found to be higher compared to that observed on conventionally prepared catalysts. Contrary to the general observation that low dispersed Pd catalysts are preferable for high stability, by means of the deposition-precipitation method adopted for catalyst preparation it was demonstrated that even highly dispersed (low Pd containing) catalysts can exhibit comparable activity and stability. An analysis of the nature of Pd species and its role in the stability of the catalysts is presented.IICT communication No. 051224 相似文献
8.
A number of complexes of Co(II), Ni(II), Cu(II), Ru(II), Pd(II) and Pt(II) with 2-methyl-3-(carboxy methyl) quinazolin (3H)-4-one
(MCMQ) and 2-phenyl-3-(carboxy methyl) quinazolin (3H)-4-one (PCMQ) have been synthesized and characterized by analytical,
conductivity, thermal, magnetic, infrared, electronic, proton magnetic resonance and electron spin resonance spectral data.
Based on analytical data, the stoichiometry and the association with other molecules of the complexes have been determined.
Conductivity data show that all these complexes are nonelectrolytes. Infrared and PMR spectral data indicate that both the
ligands are uninegative bidentate with all the metal ions. Based on electronic spectral data, the geometries of the complexes
have been indicated. Electronic spectral parameters for Co(II) and Ni(II) and ESR parameters for Cu(II) complexes have been
calculated and relevant conclusions have been drawn with respect to the nature of bonds present in them. 相似文献
9.
Lingaiah Nagarapu Hanmant K. Gaikwad Rajashaker Bantu Sheeba Rani Manikonda C. Ganesh Kumar Sujitha Pombala 《Tetrahedron letters》2012,53(10):1287-1291
A series of glycosidic-pyrroloquinolinone based novel building blocks of camptothecin (2a–g) were synthesized via Lewis acid-assisted olefin cross-metathesis reaction using Ti(OiPr)4 30 mol % and 10 mol % of Grubb’s second generation catalyst with good to excellent yields. Most of these compounds exhibited significant growth inhibitory effects on all the tested cancer cell lines and three compounds (2c, 2d and 2e) showed potent cytotoxic activity. 相似文献
10.
Complexes of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with 3-(2-pyridyl)-1-(2-hydroxy phenyl)-2-propen-1-one (PHPO), 3-(1-naphthyl)-1-(2-hydroxy
phenyl)-2-propen-1-one (NHPO) and 3-(3,4-dimethoxy phenyl)-1-(2-hydroxy phenyl)-2-propen-1-one (DMPHPO) have been synthesized
and characterized by analytical, conductivity, thermal, magnetic, infrared, electronic and electron spin resonance data. Based
on analytical data the stoichiometry of the complexes has been found to be 1 : 2. The conductivity data show that all these
complexes are non-electrolytes. The infrared spectral data indicate that the ligand PHPO acts as uninegative tridentately
towards Co(II) and Ni(II) and bidentately with Cu(II), Zn(II) and Cd(II). Ligands like NHPO and DMPHPO act as uninegative
bidentately with all the metal ions. The electronic spectral data suggest that all the Co(II) complexes and Ni(II) of PHPO
complex are octahedral and all the Cu(II) and Ni(II) of NHPO and DMPHPO complex are square-planar. The complex of Zn(II) and
Cd(II) are tetrahedral. ESR parameters of Cu(II) complexes have been calculated and relevant conclusions have been drawn with
respect to the nature of bonds present in them. 相似文献