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991.
Shyam Babu Singh Pankaj Kumar Verma Kamleshwar Tiwari Mandavi Singh Preyas Ankit Shahin Fatma 《合成通讯》2014,44(12):1795-1802
An efficient triphenylphosphine-catalyzed synthesis of β-acetamido carbonyls via multicomponent reaction of aromatic aldehydes, enolizable ketones or β-keto esters, acid chlorides and acetonitrile at room temperature is described. The process is remarkably simple, environmentally benign, and uses Lewis base for the first time in such type of reaction. 相似文献
992.
Vommina V. Suresh Babu Ganga-Ramu Vasanthakumar Subramanyam J. Tantry 《Tetrahedron letters》2005,46(23):4099-4102
An expedient synthetic approach to N-silylamines has been developed. The protocol, using TMS-Cl/zinc dust instead of BSA, is useful for the conversion of amines or amino acid esters to the corresponding silyl derivatives, followed by acylation with an acyl chloride or Fmoc-amino acid chloride to give the corresponding amide or peptide. This procedure, affording products in good to excellent yields, is also efficient for the coupling of sterically hindered amino acids like α,α-dialkylamino acids and NMe-amino acids. Further, the use of an equimolar quantity of organic base, such as Et3N/pyridine, is circumvented. 相似文献
993.
The synthesis of (3S,4R,5R)-3-(2-hydroxyethyl)piperidine-3,4,5-triol 10 has been described from d-glucose. The base promoted cyclization for the construction of the piperdine framework is the key step of the synthesis. 相似文献
994.
A series of 1-oxo-2,4-diphenyl-3-thioxobenzo[g]pyrimido[6,5-b]-1,8-naphthyridines has been synthesized by Knoevenagel condensation from 3-formyl-2-oxoquinolines and N,N-diphenyl-2-thiobarbituric acid on refluxing with liquid ammonia in absolute ethanol.Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1723–1725, November, 2004. 相似文献
995.
The electronic effects of sulfur in gamma-sulfenyl enones are not transmitted to the carbonyl carbon through the pi bond as reported previously. The diastereoselectivity is rather controlled by a combination of several other factors. The steric effects arising from the substituents on the sulfur atom and the gamma-carbon and the bulk of the nucleophile constitute the major control elements. 相似文献
996.
Hrdlicka PJ Babu BR Sørensen MD Wengel J 《Chemical communications (Cambridge, England)》2004,(13):1478-1479
Very efficient interstrand communication systems in nucleic acid duplexes, based on pyrene excimer formation between 2'-N-(pyren-1-yl)methyl-2'-amino-LNA monomers, demonstrate the versatility of functionalized 2'-amino-LNA monomers for Angstrom-scale chemical engineering. 相似文献
997.
In the present study, adsorbent is prepared from neem leaves and used for Cr(VI) removal from aqueous solutions. Neem leaves
are activated by giving heat treatment and with the use of concentrated hydrochloric acid (36.5 wt%). The activated neem leaves
are further treated with 100 mmol of copper solution. Batch adsorption studies demonstrate that the adsorbent prepared from
neem leaves has a significant capacity for adsorption of Cr(VI) from aqueous solution. The parameters investigated in this
study include pH, contact time, initial Cr(VI) concentration and adsorbent dosage. The adsorption of Cr(VI) is found to be
maximum (99%) at low values of pH in the range of 1-3. A small amount of the neem leaves adsorbent (10 g/l) could remove as
much as 99% of Cr(VI) from a solution of initial concentration 50 mg/l. The adsorption process of Cr(VI) is tested with Langmuir
isotherm model. Application of the Langmuir isotherm to the system yielded maximum adsorption capacity of 62.97 mg/g. The
dimensionless equilibrium parameter, R
L, signifies a favorable adsorption of Cr(VI) on neem leaves adsorbent and is found to be between 0.0155 and 0.888 (0<R
L<1). The adsorption process follows second order kinetics and the corresponding rate constant is found to be 0.00137 g/(mg)
(min). 相似文献
998.
999.
V. Srinivasa Rao M. Srinivasa Reddy K. Thomas S. S. Raju B. L. Rani B. Hari Babu 《Journal of solution chemistry》2018,47(3):430-448
The density (ρ), speed of sound (u) and refractive index (nD) of [Bmim][PF6], 2-pyrrolidone and their binary mixtures were measured over the whole composition range as a function of temperature between (303.15 and 323.15)?K at atmospheric pressure. Experimental values were used to calculate the excess molar volumes \( \left( {V_{m}^{\text{E}} } \right) \), excess partial molar volumes \( \left( {\overline{V}_{m}^{\text{E}} } \right) \), partial molar volumes at infinite dilution \( \left( {\overline{V}_{m}^{{{\text{E}},\infty }} } \right) \), excess values of isentropic compressibility \( \left( {\kappa_{S}^{\text{E}} } \right) \), free length \( \left( {L_{\text{f}}^{\text{E}} } \right) \) and speeds of sound \( \left( {u^{\text{E}} } \right) \) for the binary mixtures. The calculated properties are discussed in terms of molecular interactions between the components of the mixtures. The results reveal that interactions between unlike molecules take place, particularly through intermolecular hydrogen bond formation between the C2–H of [Bmim][PF6] and the carbonyl group of pyrrolidin-2-one. An excellent correlation between thermodynamic and IR spectroscopic measurements was observed. The observations were further supported by the Prigogine–Flory–Patterson (PFP) theory of excess molar volume. 相似文献
1000.
Ti-loaded ZnO and Ti-loaded ZnO/ZnO nanoparticles have been synthesized by sol–gel method and analyzed for photocatalyst application. The phase confirmation was analyzed by powder XRD and surface morphology with HR-SEM and EDAX spectrum. The particle size measured using HR-TEM and SAED pattern confirms the crystalline nature of Ti-loaded ZnO and Ti-loaded ZnO/ZnO nanoparticles. The optical properties were studied with UV–visible diffuse reflectance spectra. The DRS of Ti-loaded ZnO/ZnO nanoparticles are similar to those of pristine ZnO nanoparticles. The KM plots show both the synthesized Ti-loaded ZnO/ZnO and Ti-loaded ZnO exhibit in UV-A region. The electric properties are studied with impedance analyzer, and the results show the charge-transfer resistance of Ti-loaded ZnO/ZnO is larger than that of Ti-loaded ZnO nanoparticles. The photocatalytic activity was studied with methylene blue dye and phenol degradation by Ti-loaded ZnO/ZnO, Ti-loaded ZnO, TiO2 and ZnO nanoparticles. The photocatalytic activity of Ti-loaded ZnO/ZnO nanospheres is slightly higher than that of other nanoparticles, which shows that they have excellent application as photocatalyst. 相似文献