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101.
An efficient alumina-supported CuO-catalyzed O-arylation of phenols and aliphatic alcohols with various aryl as well as heteroaryl halides under ligand-free conditions are reported. This protocol provides a variety of diaryl ether and bis-diaryl ether motifs by reacting different aryl/aliphatic halides with differently substituted phenols and saturated alcohols in the presence of a catalytic amount of CuO on alumina and KOH as a base at moderate temperature under nitrogen atmosphere. The described methodology is simple, straightforward and efficient to afford the cross-coupled products in high yields under ligand-free conditions. The explored catalyst is inexpensive, air-stable and recyclable up to three cycles. 相似文献
102.
Konkala Karnakar Jilla Shankar Sabbavarapu Narayana Murthy Yadavalli Venkata Durga Nageswar 《Helvetica chimica acta》2011,94(5):875-880
Various phenyl and p‐tolyl allyl sulfone derivatives were prepared stereoselectively by reacting Baylis? Hillman acetates with sodium 4‐R‐benzenesulfinate (R=H, Me) in H2O. The reaction was very efficient in providing the corresponding sulfone derivatives in good to excellent yields (Table). 相似文献
103.
Lingam Venkata Reddy Mamatha Nakka Alishetty Suman Soumen Ghosh Madeleine Helliwell Khagga Mukkanti Alok Kumar Mukherjee Sarbani Pal 《Journal of heterocyclic chemistry》2011,48(3):555-562
Reduction of nimesulide followed by treating the N‐acyl derivative of resulting arylamine with Vilsmeier‐Haack reagent provided novel 2‐chloro‐3‐formylquinoline derivatives. The construction of quinoline ring using Vilsmeier‐Haack reagent afforded an unexpected compound, N‐(2‐chloro‐3‐formyl‐7‐phenoxy quinolin‐6‐yl)formamide, in addition to the expected product. The structure of this unexpected quinoline derivative was established via single‐crystal X‐ray analysis and its formation could be explained by an unprecedented N‐S bond cleavage under Vilsmeier‐Haack reaction conditions. The 2‐chloro‐3‐formylquinoline derivatives obtained were converted to a number of corresponding Schiff bases with potential pharmacological importance. J. Heterocyclic Chem., 2011. 相似文献
104.
Kokatla HP Thomson PF Bae S Doddi VR Lakshman MK 《The Journal of organic chemistry》2011,76(19):7842-7848
Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis(pinacolato)- and in some cases bis(catecholato)diboron [(pinB)(2) and (catB)(2), respectively]. Reductions occur upon simply mixing the amine N-oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N'-dioxide of (S)-(-)-nicotine. Because it was observed that (pinB)(2) was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)(2), triethylborane reduced alkylamino-N-oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)(2) has been probed by (1)H and (11)B NMR. 相似文献
105.
106.
Rao TR Krishna ChR Reddy ChV Thampy US Reddy YP Rao PS Ravikumar RV 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1116-1122
Optical and physical properties of Ni2+ doped 20ZnO+xLi2O+(30-x)Na2O+50B2O3 (5≤x≤25) glasses are carried out at room temperature. Powder XRD pattern of all the glass samples confirms the amorphous nature. Several physical parameters are evaluated for all the glasses with respect to the composition. The optical absorption spectra confirm the site symmetry of the Ni2+ doped glasses are near octahedral. Crystal field and inter-electronic repulsion parameters are also evaluated. It is interesting to observe that the optical band gap and Urbach energies exhibit the mixed alkali effect. The FT-IR spectral investigations of Ni2+ doped glasses exhibit characteristic vibrations of BO3 and BO4 units. 相似文献
107.
Nanostructured MnO(2) exhibits a high turnover frequency for oxygen evolution under visible light and high stability in strong acidic conditions. 相似文献
108.
Hrudananda Jena R. Venkata Krishnan R. Asuvathraman K. Nagarajan K. V. Govindan Kutty 《Journal of Thermal Analysis and Calorimetry》2011,106(3):875-879
Ba10−x
Cs
x
(PO4)6Cl2, (x = 0, 0.5) chloroapatite ceramics were prepared by sonochemical method of synthesis. The measured room temperature lattice
parameters of Ba10 (PO4)6Cl2 and Ba9.5Cs0.5 (PO4)6Cl2−δ are practically the same; that is, a = 10.26 (8), c = 7.65 (7) and a = 10.27 (7), c = 7.65 (5), respectively. Heat capacity measurements were carried out on these materials by differential scanning calorimetry
(DSC) in the temperature range 298–800 K. The heat capacity values of Ba9.5Cs0.5(PO4)6Cl2−δ are found to be slightly higher at all temperatures than those of Ba10(PO4)6Cl2. From the heat capacity data, other thermodynamic functions such as enthalpy and entropy increments were computed. The heat
capacity values of Ba10(PO4)6Cl2 and Ba9.5Cs0.5(PO4)6Cl2−δ at 298 K are 0.3912 and 0.4310 J K−1 g−1, respectively. Thermal expansion property of the doped and undoped barium chloroapatites was measured by using a home built
dilatometer which uses LVDT as displacement sensor. The bulk thermal expansion of Ba10(PO4)Cl2 and Ba9.5Cs0.5(PO4)Cl2−δ is observed to be about 0.9% in the temperature range of 298–973 K. 相似文献
109.
This paper reports the method of preparation and the emission level assignments for the light emitting powder phosphors of CaS:Er3+ and CaS:Tb3+. The recorded photoluminescence spectra of these powder phosphors have shown that the light emission would be better at lower dopant concentrations. 相似文献
110.
The new enhancement in the determination of pH using optical fiber system is described here. This work uses the membrane made of cellulose acetate membrane for reagent immobilization and congo red (pKa 3.7) and neutral red (pKa 7.2) as pH indicators. An effective covalent chemical binding procedure is used to immobilize the indicators. The response time, reversibility, linear range, reproducibility, and long-term stability of fiber optic sensor with congo red as well as neutral red have been determined. The linear range measured for the sensor based on the congo red and neutral red is 4.2-6.3 and 4.1-9.0, respectively. The response time of sensor membrane is measured by varying the substance pH values between 11.0 and 2.0. 相似文献