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41.
Herein we report the synthetic strategy towards the pyran core of macrolactin 3 via Sharpless epoxidation, titanium(IV) mediated regioselective ring-opening reaction of epoxyallyl alcohol/epoxy alcohol and oxa-Michael addition as the key steps. 相似文献
42.
T. SuhasiniB.C. Jamalaiah T. ChengaiahJ. Suresh Kumar L. Rama Moorthy 《Physica B: Condensed Matter》2012,407(3):523-527
Different concentrations of Ho3+-doped lead borate titanate aluminum fluoride (LBTAFHo) glasses with chemical composition of PbO-H3BO3-TiO2-AlF3-Ho2O3 were prepared by the melt quenching method. The spectral properties were investigated using the absorption, emission and decay measurements. The experimental oscillator strengths were calculated from the area under the absorption bands. Applying Judd-Ofelt theory, the intensity parameters (Ωλ=2, 4, 6) were calculated, by the least square fit approach from which the radiative transition rates, luminescence branching ratios and radiative decay times were determined. The photoluminescence spectra revealed the quenching of luminescence intensity beyond 1.0 mol% of Ho3+ ion concentration. To investigate the luminescence potentiality of 5F4→5I8 emission level, the effective bandwidth and the stimulated emission cross-section were determined. The quenching in experimental decay time is attributed to the resonance energy transfer among the excited Ho3+ ions. 相似文献
43.
Abstract On radiolysis tris(acetylacetonato) cobalt(III) in aqueous solutions is found to get reduced by reaction with (1) hydrated electrons, (2) H atoms, (3) OH radicals and (4) C2H2OH radicals. The bimolecular rate constants for the first three reactions, determined by competition kinetics are: 4 × 1010, 2.3 × 109 and 4.7 × 109 M?1sec?1 respectively. Absorption spectra of the irradiated solutions indicate the formation of bis(acetylacetonato) cobalt(II) from reaction (1), but not from (3). The total cobaltous yield in air-free solutions is given byG(Co++) = 5.6 and 6.5 at pH 6.5 and 1 respectively. It appears that Geaq- ∽ H + GoH ∽ 2.8 in neutral solutions. Considerations of material balance for the primary yields of radiolysis of water suggest the possibility that the so-called independent H-atoms in neutral solutions are probably excited water molecules or ion-pairs. 相似文献
44.
Nahar Singh Rama Devi Ramachandran Ajit Kumar Sarkar 《International journal of environmental analytical chemistry》2013,93(10):891-896
Silica is removed from fly ash sample by hydroflourination for its effective determination gravimetrically and the remaining residue is subjected to lithium tetraborate (Li2B4O7) fusion followed by dissolution in dilute nitric acid to obtain a clear solution in which elements including aluminum (Al), iron (Fe), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu) and zinc (Zn), have been determined by Flame Atomic Absorption Spectrometry (FAAS). Two fly ash samples analyzed by the proposed method have been received from the National Council of Cement and Building Materials (NCCBM), India (proposed CRM in future) and fly ash CRM 1633 (b) from NIST, USA. The validity of the method has been established by analyzing fly ash CRM 1633 (b) as reference standard. The standard deviation has been calculated for each measurement. 相似文献
45.
The discovery of synthetic pyrethroids with increased insecticidal activity and low mammalian toxicity led to abundance of new synthetic results in the chemistry of pyrethroids1 . Many of these methods adopted on an industrial scale make use of sigmatropic rearrangement, radical addition and nucleophilic ring closer with carbanions. Herein we report a simple and stereospecific route for the synthesis of ethyl trans-chrysanthernate (1) by utilizing carbonyl stabilized sulphuranes. Although the use of Sulphurane was demonstrated at a much earlier stage for the synthesis of methyl trans-chrysanthe-mate2, the present approach makes use of simple reagents and offers some operational advantages. 相似文献
46.
Abstract Acrylamide has been polymerized electrochemically in aqueous medium in the presence of tartaric acid, and the effects of such reaction variables as monomer concentration, electrolyte concentration, and current on the rates of polymerization have been studied. The mechanisms of initiation and termination have been discussed in the light of the observed kinetic data. Initiation is believed to occur through the generation of radical ions during electrolysis, and electrolytic termination is found to be negligible during the polymerization process. 相似文献
47.
48.
Rama Raju Baadhe Naveen Kumar Mekala Satwik Reddy Palagiri Sreenivasa Rao Parcha 《Applied biochemistry and biotechnology》2012,167(5):1172-1182
In this case study, we designed a farnesyl pyrophosphate (FPP) biosynthetic network using hybrid functional Petri net with extension (HFPNe) which is derived from traditional Petri net theory and allows easy modeling with graphical approach of various types of entities in the networks together. Our main objective is to improve the production of FPP in yeast, which is further converted to amorphadiene (AD), a precursor of artemisinin (antimalarial drug). Natively, mevalonate (MEV) pathway is present in yeast. Methyl erythritol phosphate pathways (MEP) are present only in higher plant plastids and eubacteria, but not present in yeast. IPP and DAMP are common isomeric intermediate in these two pathways, which immediately yields FPP. By integrating these two pathways in yeast, we augmented the FPP synthesis approximately two folds higher (431.16 U/pt) than in MEV pathway alone (259.91 U/pt) by using HFPNe technique. Further enhanced FPP levels converted to AD by amorphadiene synthase gene yielding 436.5 U/pt of AD which approximately two folds higher compared to the AD (258.5 U/pt) synthesized by MEV pathway exclusively. Simulation and validation processes performed using these models are reliable with identified biological information and data. 相似文献
49.
Aqueous solution of potassium persulfate converts water-insoluble carboxylic acids in ether (or dichloromethane), to peracids in a yield of 80–90% under the catalytic influence of benzyltriethylammonium chloride (BTEAC) or polyethyleneglycol (PEG-400). The reaction is further catalyzed kinetically in presence of a sulfonated polymer. 相似文献
50.
Mallikarjun Reddy Sura Vasu Govardhana Reddy Peddiahgari Rajendra Prasad Reddy Bhoomireddy Rama Krishna Vadde 《Journal of heterocyclic chemistry》2013,50(6):1395-1399
A new series of 2,4‐diaryl‐6‐methyl‐5‐nitropyrimidines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i ) were synthesized in good yields by Suzuki–Miyaura coupling of 2,4‐dichloro‐6‐methyl‐5‐nitropyrimidine ( 3 ) with various aryl boronic esters ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i ) in the presence of 1,1′‐ bis(diphenylphosphino)ferrocene dichloropalladium(II) (Pd(dppf)2Cl2). Further, antibacterial and antioxidant properties were screened for the title compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i . Most of the compounds possessed significant activity against Gram‐positive bacteria Staphylococcus aureus and Bacillus subtilis and Gram‐negative bacteria Escherichia coli and Klebsiella pneumoniae. The antioxidant activity of the title compounds showed significant antioxidant activity when compared with vitamin C. 相似文献