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11.
Dr. Nilofar Baral Soniya Rani Pinku Saikia Dr. Pradip Maity 《European journal of organic chemistry》2023,26(4):e202201238
Organophosphites are nucleophilic in nature and can act as a good leaving group owing to the stability of the phosphite anion. This dual reactivity makes them good candidates for nucleophilic organocatalysis. However, phosphites were introduced only in 2004 as the umpolung catalyst for acylsilane substrates utilizing sequential Brook rearrangements. Very recently, phosphites have been reported to catalyze aza-rearrangements and radical reactions. In this review, we discuss the reactivity parameters to understand its lack of use, as well as the potential for catalysis. 相似文献
12.
Bharat Baral Pawan Kumar Brooke A. Anderson Michael E.
stergaard Pawan K. Sharma Patrick J. Hrdlicka 《Tetrahedron letters》2009,50(42):5850-5852
A short and high-yielding synthetic route to [3-15N]-labeled uridine phosphoramidite 1 (26% overall yield from uridine) has been developed. This will enable automated synthesis of isotopically labeled RNA strands and facilitate their use in structural studies. 相似文献
13.
The excited state intramolecular proton transfer (ESIPT) processes in 3‐methylsalicyclic acid (3‐MeSA) and 3‐methoxysalicyclic acid (3‐MeOSA) have been investigated in cyclohexane medium by emission spectroscopic techniques. The ESIPT process was characterized in 3‐MeSA from the large Stokes fluorescent band (455 nm), but it was suppressed by 3‐MeOSA in cyclohexane. The ESIPT process was found to be accelerated both in 3‐MeSA and 3‐MeOSA in the presence of a hydrogen bond accepting agent, triethylamine (TEA). Further, theoretical calculations were carried out at the ground and excited states to complement the experimental evidences. 相似文献
14.
Rita Cimino Sukhvir Kaur Bhangu Anshul Baral Muthupandian Ashokkumar Francesca Cavalieri 《Molecules (Basel, Switzerland)》2021,26(17)
Ultrasonically synthesized core-shell microcapsules can be made of synthetic polymers or natural biopolymers, such as proteins and polysaccharides, and have found applications in food, drug delivery and cosmetics. This study reports on the ultrasonic synthesis of microcapsules using unmodified (natural) and biodegradable glycogen nanoparticles derived from various sources, such as rabbit and bovine liver, oyster and sweet corn, for the encapsulation of soybean oil and vitamin D. Depending on their source, glycogen nanoparticles exhibited differences in size and ‘bound’ proteins. We optimized various synthetic parameters, such as ultrasonic power, time and concentration of glycogens and the oil phase to obtain stable core-shell microcapsules. Particularly, under ultrasound-induced emulsification conditions (sonication time 45 s and sonication power 160 W), native glycogens formed microcapsules with diameter between 0.3 μm and 8 μm. It was found that the size of glycogen as well as the protein component play an important role in stabilizing the Pickering emulsion and the microcapsules shell. This study highlights that native glycogen nanoparticles without any further tedious chemical modification steps can be successfully used for the encapsulation of nutrients. 相似文献
15.
The aqueous polymerization of methyl methacrylate initiated by the redox system K2S2O8-ascorbic acid has been studied at 35°C under the influence of oxygen. The rate of polymerization increases with increasing ascorbic acid concentration at low activator concentration, remains constant within the range 4.375 × 10?3 to 11.25 × 10?3 mole/liter, and at higher ascorbic acid concentration again decreases. The rate varies linearly with monomer concentration. The initial rate and the limiting conversion increase with increasing polymerization temperature. Organic solvents (water-miscible only) and small amounts of neutral salts like KC1 and Na2SO4 depress the initial rate and the maximum conversion. The addition of small amounts of salts like Cu2+ and Mn2+ increases the initial rate, but no appreciable increase in the limiting conversion is observed. 相似文献
16.
Sudhansu Bhusan Dash Nilamber Baral Nrusingha C. Pati Padma L. Nayak 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7-8):1123-1134
Abstract The kinetics of the aqueous polymerization of acrylonitrile initiated by the peroxydiphosphate-thioacetamide redox system was investigated at 35, 40, and 50°C. The rates of polymerization were measured at different concentrations of oxidant, activator, and monomer. Peroxydiphosphate alone did not initiate polymerization under deaerated and undeaerated conditions. Addition of certain water-miscible organic solvents and neutral salts depress the rate and conversion. On the basis of experimental observations of the dependence of the rate of polymerization on various variables, a suitable kinetic scheme has been proposed. 相似文献
17.
Baral Pratibha Munagala Meghana Shastri Yogendra Kumar Vinod Agrawal Deepti 《Cellulose (London, England)》2021,28(10):6305-6322
Cellulose - In an enzymatically driven lignocellulosic biorefinery, pretreatment and hydrolysis modules are the two most significant cost contributors for obtaining high gravity sugar solutions.... 相似文献
18.
Mohan Giri Suman Baral Gopi Chandra Kaphle Nirmal Dangi Sudip Shiwakoti Leonardo Bardomero Paul Lashomb Walter Wilcox 《理论物理通讯》2021,73(3):35202-104
Using the Thomas-Fermi quark model,a collective,spherically symmetric density of states is created to represent a gas of interacting fermions with various degeneracies at zero temperature.Over a family of pentaquarks,uudcc,color interaction probabilities were obtained after averaging over all the possible configurations.Three different functions are developed for light,charm,and anti-charm quarks and are assumed to be linearly related by some proportionality constants.Interesting patterns of quark distributions are observed while analyzing the quark function consistency conditions for such constants. 相似文献
19.
Suban K. Sahoo Minati Baral Rati Kanta Bera B. K. Kanungo 《Journal of solution chemistry》2011,40(7):1187-1199
The aqueous coordination behavior of two novel tripodal imine-phenol ligands, cis,cis-1,3,5-tris{(2-hydroxybenzilidene)aminomethyl}cyclohexane (TMACHSAL, L1) and cis,cis-1,3,5-tris{[(2-hydroxyphenyl)ethylidene]aminomethyl}cyclohexane (Me3- TMACHSAL, L2) with Al3+ and Ga3+ has been investigated at an ionic strength of 0.1 mol⋅dm−3 KCl and 25±1 °C by potentiometric and spectrophotometric methods. Both ligands formed various monomeric metal complex species
MLH3, MLH2, MLH, ML and MLH−1 with Ga(III); and MLH3, ML and MLH−1 with Al(III). The Ga(III) complexes showed higher thermodynamic stability than the Al(III) complexes. Semi-empirical PM6
calculations along with TDDFT/B3LYP/3-21G calculations have been performed to complement the experimental measurements. The
calculated structure of the metal complexes predicted a distorted octahedral geometry where favorable ring-flipping from the
equatorial conformation in uncomplexed ligands to the axial conformation was observed upon chelation. 相似文献
20.
Photophysical properties of a multidentate tripodal ligand, 5,5′-(2-(((8-hydroxyquinolin-5-yl) methylamino)methyl)-2-methylpropane-1,3-diyl) bis (azanediyl)bis (methylene)diquinolin-8-ol, (TAME5OX), with La3+ and Er3+ ions have been examined for photonics applications. The change in behavior in electronic spectra of these complexes reveals the use of TAME5OX as a sensitive optical pH based sensor to detect Ln3+ ions whereas indication of strong green fluorescence allows simultaneous sensing within the visible region in competitive medium. The intense fluorescence intermittently gets quenched under acidic and basic conditions due to photoinduced intramolecular electron transfer from the excited 8-hydroxyquinoline (8-HQ) moiety to the metal ion. This renders these compounds the OFF-ON-OFF type of pH-dependent fluorescent sensor. The thermodynamic stability and coordination behaviour of the chelator with the said lanthanide ions have also been probed by potentiometric, UV ? visible and fluorescence spectrophotometric method. TAME5OX forms protonated complex [Ln (H4L)]4+ below pH ~4.0 which sequentially deprotonates through one proton process with increase of pH. The stability constants of neutral complexes have been determined to be in the range log β110 = 32–34 and pLn in the range of 14–20, indicating TAME5OX is a good synthetic lanthanide chelator. Theoretical spectra were also calculated by ZINDO/s methodology at single excitations (CIS) level on PM7 as sparkle energy-minimized geometries. 相似文献