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排序方式: 共有346条查询结果,搜索用时 15 毫秒
51.
52.
A series of CuO/Al(2)O(3)-ZrO(2) catalysts with Cu loadings varying from 1.0 to 20 wt % were prepared and characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD) of CO(2) and NH(3), electron spin resonance (ESR), and Brunauer-Emmett-Teller surface area measurements. The dispersion and metal area of copper were determined by the N(2)O decomposition method. XRD results suggest that the copper oxide is present in a highly dispersed amorphous state at copper loadings < 10 wt % and as a crystalline CuO phase at higher Cu loadings. ESR results suggest the presence of two types of copper species on the Al(2)O(3)-ZrO(2) support. TPR results suggest well-dispersed copper oxide species at low Cu loadings and crystalline copper oxide species at high Cu loadings. Well-dispersed copper oxide species were reduced more easily than large copper oxide species by H(2). The results of CO(2) TPD suggest that the basicity of the catalysts was found to increase with an increase of copper loading up to 5.0 wt % and decreases with a further increase of copper loading. The results of NH(3) TPD suggest that the acidity of the catalysts was found to decrease with an increase of copper loading up to 5.0 wt % and increases with a further increase of copper loading. The catalytic properties were evaluated for the vapor-phase dehydrogenation of cyclohexanol to cyclohexanone and correlated with the results of CO(2) TPD measurements and the dispersion of Cu on the Al(2)O(3)-ZrO(2) support. 相似文献
53.
D.G.S. Sudhakar Ch. Venkata Ramana Reddy Srinivasa Rao Alapati 《Tetrahedron letters》2019,60(37):151027
An efficient stereoselective total synthesis of balticolid has been accomplished starting from known aldehyde. The key steps involved in this synthesis are Sharpless asymmetric epoxidation, Wittig olefination, alkylation of 1,3-dithiane and Yamaguchi macrolactonization. 相似文献
54.
Mydhili S. P. Sireesha B. Reddy Ch. Venkata Ramana 《Russian Journal of General Chemistry》2019,89(5):1015-1022
Russian Journal of General Chemistry - Evaluation of stability constants of the complexes formed in solution by the biologically important ligands and metal ions can aid in understanding the... 相似文献
55.
56.
We have developed methodology for the synthesis of aryl/alkyl cyanamides from amines in one-pot four steps reaction using cheap, readily available and air stable copper source as catalyst under mild reaction conditions. We have also studied the application of cyanamides. In this connection, we could construct aryl tetrazolamine from cyanamides using click reaction 相似文献
57.
Prasad Mishra G Venkata Ramana G Venkateswara Rao B 《Chemical communications (Cambridge, England)》2008,(29):3423-3425
A new, efficient and highly diastereoselective approach for the synthesis of 1,2,3,5-tetraacetylcarba-alpha-D-lyxofuranose from D-ribose is reported via one-pot conversion of to using Tebbe reagent which involves a cascade reaction sequence of methylenation, cleavage of isopropyl group, carbocyclization and again methylenation. 相似文献
58.
Ramana CV Khaladkar TP Chatterjee S Gurjar MK 《The Journal of organic chemistry》2008,73(10):3817-3822
A flexible approach for total syntheses of possible multiplolide A diastereomers establishing the relative and absolute configuration is documented. The adopted strategy features ring-closing metathesis (RCM) as the key reaction and screening of a set of substrates for the feasibility of RCM in general and for the requisite E-configuration of ring olefin in particular. Selective protecting groups manipulation prior to the assembly of the central macrocyclic core was instrumental in installing the epoxide functionality on a fully deprotected nonenolide at the end of the synthesis. 相似文献
59.
Synthesis of α‐Benzylthiobenzimidazoleacetonitriles and Their Chemoselective Reduction of the Double Bond with NaBH4
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Srinivas Rao Sadhu Chittireddy Venkata Ramana Reddy Pramod Kumar Dubey 《Journal of heterocyclic chemistry》2016,53(1):74-79
Condensation of 2‐((1H‐benzimidazol‐2‐yl)thio)acetonitre 1 with aromatic aldehydes in methanol containing piperidine gave the corresponding 2‐((1H‐benzimidazol‐2‐yl)thio)‐3‐arylacrylonitrile 2 , which on treatment with NaBH4 in ethanol unexpectedly and chemoselectively gave 2‐((1H‐benzimidazol‐2‐yl)thio)‐3‐arylpropanenitrile 3 by the reduction of the double bond of 2 . 3 on methylation with dimethyl sulfate containing K2CO3 as a base and tetrabutylammonium bromide as PTC gave 2‐((1‐methylbenzimidazol‐2‐yl)thio)‐3‐arylpropanenitrile 6 . The latter could also be prepared in an alternative way by reaction of 1 with dimethyl sulfate giving the intermediary 2‐((1‐methylbenzimidazol‐2‐yl)thio)acetonitrile 4 , followed by condensation with aromatic aldehydes yielding 5 and subsequent reduction of 5 with NaBH4 in methanol. 6 could be directly synthesized by treatment of 4 with benzyl chloride in DMF and triethylamine as a base at 60°C for 5 h. 相似文献
60.
Qayyum M Venkatram Reddy B Ramana Rao G 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(1-2):279-290
The Raman and Fourier transform infrared (FTIR) spectra of p-, m- and o-nitrobenzamides, p-, m- and o-nitrobenzaldehydes and p-, m- and o-nitrotoluenes were recorded. Raman polarisation measurements were made for the liquid samples. A normal coordinate analysis was carried out for both in-plane and out-of-plane vibrations of these molecules using 111-parameter modified valence force field. The force constants were refined using 316 frequencies of nine molecules in an overlay least-square technique. The reliability of the force constants was tested by making a zero-order calculation for nine related molecules. Unambiguous vibrational assignments of all the fundamentals were made by using the potential energy distributions and eigen vectors. 相似文献