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31.
Urja Narang Prabhakar Singh Prof. Dr. Srinivasarao Arulananda Babu 《European journal of organic chemistry》2023,26(29):e202300463
This paper describes the Pd(II)-catalyzed, picolinamide-directing-group-aided C(sp2)−H (ortho) functionalization of racemic and enantiopure β-phenylalanines and 3-amino-3-phenylpropanols (1,3-amino alcohols). The C(sp2)−H (ortho) functionalizations including arylation, bromination, iodination, and alkoxylation were attempted. The C(sp2)−H (ortho) arylation reactions gave biaryl or terphenyl-type β-phenylalanine scaffolds, halogenation and methoxylation reactions gave ortho C−H halogenated or methoxylated β-phenylalanines. Additionally, the C−H arylation of an ortho-methyl substituted β-phenylalanine containing both C(sp2)−H and remote C(sp3)−H bonds was investigated. β-Phenylalanine is an arylated β-amino acid motif present in various natural products, bioactive molecules, and β-peptides and it is a precursor to medicinally active compounds. Accordingly, this work contributes to the expansion of the library of unnatural β-phenylalanine (β-amino acid) derivatives through site-selective C−H functionalization. 相似文献
32.
Manoj K. Sahani Divya Singhal Ajay K. Jain Udai P. Singh Shikha Narang 《International journal of environmental analytical chemistry》2016,96(12):1170-1187
Novel ligand 5,5?-((3-nitrophenyl)methylene)bis(2,6-diaminopyrimidin-4(3H)-one) (L) was synthesised and characterised. Preliminary studies on L have showed that it has more affinity towards the Ni2+ ion. Thus, the L was used as the electroactive material in the fabrication of poly(vinyl chloride) (PVC)-based membrane sensors such as coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE). Several polymeric membranes were fabricated by incorporating L as ionophore, NaTPB as anion excluders and BA, 1-CN, DBP, DOP and o-NPOE as solvent mediators and their effect on potentiometric response studied. Comparative electroanalytical studies performed on the CGE and CPGE depict that the CPGE with optimised membrane composition of L:PVC:o-NPOE:NaTPB in the ratio of 7:33:58:2 (w/w, mg) exhibited the best response in terms of wide working concentration range from 2.0 × 10?8 to 1.0 × 10?1 mol L?1, (3.64 µg L?1 –18.2 g L?1) lower detection limit of 8.1 × 10–9 mol L?1 (1.47 µg L?1) with Nernstian compliance of 29.4 ± 0.2 mV decade?1 of activity of Ni2+ ion in the pH range of 3.5–9.0. The sensor can work satisfactorily in water–acetonitrile and water–methanol mixtures. It can tolerate 30% acetonitrile and 20% methanol content in the mixtures. The sensor showed fast response time of 8 s and could be used successfully for a period of 4 months. The sensor reflects its utility in the quantification of Ni2+ ion in real samples and has been successfully employed as an indicator electrode in the potentiometric titration of Ni2+ ion with EDTA. 相似文献
33.
Copolymerization of racemic propylene oxide with carbon dioxide is investigated in the presence of economically inexpensive and effective achiral salophenCo(III)X [salophen = N,N'-bis(3,5-di-tert-butylsalicylidene)-phenylenediimine, X = pentaflorobenzoate] catalyst and tetrabutyl ammonium bromide as co-catalyst. Effects of different variables like monomer to catalyst ratio, catalyst/co-catalyst ratio, temperature, pressure of CO2 on molecular weight, yield and selectivity of poly(propylene carbonate) [PPC] have been investigated. The maximum Mw of 25.8 g/mol has been obtained at 15 bar and 50°C. All the samples were found to have excellent polydispersity near to 1. 相似文献
34.
Kumar Karitkey Yadav Uma Narang Soumee Bhattacharya Shive M.S. Chauhan 《Tetrahedron letters》2017,58(31):3044-3048
Copper phthalocyanine (CuIIPc) was found to be an efficient catalyst for the catalyzed N-arylation of NH heterocycles with aryl iodides and bromides under mild reaction conditions. A variety of hindered and functionalized NH heterocycles and aryl halides were successfully used as the substrates for the given catalytic reaction and were transformed in good to excellent yields. 相似文献
35.
The application of thermodynamic perturbation theory to the computation of the properties of simple polar fluids is considered. The Helmholtz free energy of a fluid of molecules interacting via a Stockmayer potential v S is computed through fourth order in μ, where μ is the dipole moment. Numerical results are obtained on the basis of both the ‘exact’ Monte-Carlo computations for a Lennard-Jones system and the Verlet-Weis perturbation-theoretic computations for that system. The results obtained on the latter basis are then compared with results for a fluid of molecules interacting via a central-force potential v ES that is conformal with the Lennard-Jones 6–12 potential and equivalent to the Stockmayer potential through order μ4. To facilitate the comparison the v ES results are computed according to the Verlet-Weis method. The v ES results and the fourth-order (in μ) v S results constitute two different approximations to the thermodynamics of the Stockmayer potential; the compressibility factors as well as the free energies of the two approximations are compared. It is concluded that the thermodynamic contribution of the dipole term of v S is significant over the whole liquid region when μ2=εσ3, where ε and σ are the usual Lennard-Jones parameters. For this μ, the two approximations we consider give results in close agreement. 相似文献
36.
Summary Mono- and binuclear zinc(II) complexes, Zn(HL)Cl and Zn2 (L-2H), containing multidentate acyldihydrazone ligands (H2L) have been synthesized and characterized by elemental analysis, i.r. and electronic spectral data. The reaction medium, zinc(II) salt and ligand geometry influence the composition and stereochemistry of the complexes. 相似文献
37.
A sensitive and specific bioanalytical method for quantitation of a novel antiemetic (ADR-851) in plasma and urine has been developed and validated. The drug and internal standard (metoclopramide) are extracted from the plasma matrix by solid-phase extraction on cyanopropyl bonded-phase columns. After extraction, samples are separated by isocratic reversed-phase high-performance liquid chromatography. The parent drug, internal standard and a yet unidentified metabolite are detected by fluorescence. The method requires 1.0 ml of plasma or 0.1 ml of urine and has a lower limit of quantitation of 2 ng/ml with 10.9% relative standard deviation (R.S.D.). Method linearity has been established over a 2-800 ng/ml range when 1.0 ml of plasma is used. The intra- and inter-day imprecisions for the method are typically better than 6% and 11% R.S.D., respectively, in both plasma and urine over the entire dynamic range. The pooled estimate of bias is less than 5% and attests to the excellent accuracy. 相似文献
38.
A method is described for construction of an amperometric xanthine biosensor based on graphite rod modified through adsorption
of xanthine oxidase. Enzymatically produced H2O2 from xanthine was split into 2H+ + O2 + 2e− at 0.6 V and the current was measured, which was directly proportional to xanthine concentration ranging from 1 ° 10−7 to 6 ° 10−7 M with a detection limit of 1 ° 10−7 M. The biosensor exhibited optimum response within 35 sec at pH 7.0 and 35°C. It was employed for determination of xanthine
in tea leaves (0.9 ° 10−5−2.5 ° 10−5 mmol/g), coffee powder (3.2 μmol/g) and fish meat (90 mmol/g). The content of xanthine in fish meat increased 6.5 times with
its storage at room temperature during 15 days. The enzyme electrode could be reused 200 times during the span of 30 days,
when stored in reaction buffer at 4°C. 相似文献
39.
Randeep?Kaur Charanjeet?SinghEmail author Harpreet?Kaur Tanvi?Dhiman S.?Bindra Narang 《The European Physical Journal B - Condensed Matter and Complex Systems》2015,88(10):272
Microwave characterization of SrCo x Ti x Fe(12?2x)O19 (x = 0.0, 0.2, 0.3, 0.5, 0.6, 0.7, 1.0) ferrites has been studied as a function of frequency, substitution and thickness, and static electrical current density-electric field characteristics have been investigated as a function of substitution. Microwave characteristics have been measured using power meter in the rectangular slotted waveguide and current density is measured using electrometer. The microwave absorption is evaluated using the standard available model. The results depict ?11.57 dB reflection loss at 10.38 GHz in composition x = 0.6. The electrical current density decreases at lower substitution and increases at higher substitution. The substitution of Co2+ and Ti4+ ions causes enhancement of electromagnetic and static electrical properties. 相似文献
40.
An ascorbate oxidase (AsOx) (E.C.1.10.3.3) purified from Lagenaria siceraria fruit was immobilized covalently onto a carboxylated multiwalled carbon nanotubes and polyaniline (c-MWCNT/PANI) layer electrochemically deposited on the surface of an Au electrode. The diffusion coefficient of ascorbic acid was determined as 3.05 × 10(-4) cm(2) s(-1). The behavior of different electrolytes on electro-deposition was also studied. An ascorbate biosensor was fabricated using a AsOx/c-MWCNT/PANI/Au electrode as a working electrode, Ag/AgCl (3 M/saturated KCl) as standard and Pt wire as an auxiliary electrode connected through a potentiostat. Linear range, response time and detection limit were 2-206 μM, 2 s and 0.9 μM respectively. The biosensor showed optimum response at pH 5.8 and in a broader temperature range (30-45 °C), when polarized at +0.6 V. The biosensor was employed for determination of ascorbic acid level in sera, fruit juices and vitamin C tablets. The sensor was evaluated with 91% recovery of added ascorbic acid in sera and 6.5% and 11.4% within and between batch coefficients of variation respectively for five serum samples. There was a good correlation (r = 0.98) between fruit juice ascorbic acid values by the standard 2,6-dichlorophenolindophenol (DCPIP) method and the present method. The enzyme electrode was used 200 times over a period of two months, when stored at 4 °C. The biosensor has advantages over earlier enzyme sensors in that it has no leakage of enzyme, due to the covalent coupling of enzyme with the support, lower response time, wider working range, higher storage stability and no interference by serum substances. 相似文献