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231.
M. Masteri-Farahani A. Ezabadi R. Mazarei P. Ataeinia S. Shahsavarifar F. Mousavi 《应用有机金属化学》2020,34(8):e5727
Intercalation of cetyltrimethylammonium (CTA+) cations within the nanolayers of montmorillonite (MMT) clay followed by reaction with Keggin-type phosphomolybdic acid (PMo) resulted in the synthesis of (CTA)3PMo-MMT nanocomposite catalyst. The prepared nanocomposite catalyst was characterized using different physicochemical methods such as Fourier-transform infrared and inductively coupled plasma–optical emission spectroscopies, X-ray diffraction, and nitrogen adsorption–desorption (Brunauer–Emmett–Teller method) analyses. Characterization techniques demonstrated the intercalation of (CTA)3PMo species into the nanolayers of MMT. The resulting (CTA)3PMo-MMT nanocomposite catalyst efficiently catalyzed the synthesis of 2,4,5-trisubstituted imidazoles under solvent-free conditions. The efficiency is due to the fact that the presence of CTA+ species makes the nanocomposite catalyst hydrophobic and facilitates the accessibility of hydrophobic reactants to active sites in the course of the reaction. High activity and selectivity were achieved in the presence of the prepared nanocomposite catalyst. The nanocomposite catalyst was readily isolated from the reaction mixture using simple filtration, washed with ethanol, and recycled five times without a major loss of activity. 相似文献
232.
Russian Journal of Applied Chemistry - In this work, preparation and characterization of new classes of polybutadiene-based polyols and polyurethanes investigated with consecutive reactions namely,... 相似文献
233.
Ali Mohebbi Mir Ali Farajzadeh Mahboob Nemati Negin Sarhangi Mohammad Reza Afshar Mogaddam 《Biomedical chromatography : BMC》2019,33(11)
Sodium sulfate‐induced deep eutectic solvent–based solidification of floating organic droplets–dispersive liquid phase microextraction was developed prior to gas chromatography–mass spectrometry. In this method, a mixture of Na2SO4 solution (as phase separation agent and disperser) containing menthol–decanoic acid was rapidly injected into an alkaline aqueous solution containing Na2SO4. The solution was placed in an ice bath and the menthol–decanoic acid solvent was solidified on the surface of the solution. Under the optimal conditions, the enrichment factors and extraction recoveries were 122–147 and 74–89%, respectively. Finally, an aliquot of the collected organic phase was removed and mixed with acetonitrile and injected into the separation system. The limits of detection and lower limits of quantification were obtained at the ranges of 13–25 and 24–41 ng L?1, respectively. The relative standard deviations of the proposed method were ≤11% for intra‐ and inter‐day precisions at four concentrations. 相似文献
234.
Arif Rafiq Nazir Ahmad Mir Farooq Ahmad .Mathematics Department COMSATS Institute of Information Technology Islamabad Pakistan .Centre for Advanced Studies in Pure Applied Mathematics Bahauddin Zakariya University Multan Pakistan 《应用数学和力学(英文版)》2007,(7)
In account of the famous ebyev inequality,a rich theory has appeared in the literature.We establish some new weighted ebyev type integral inequalitíes.Our proofs are of independent interest and provide new estimates on these types of inequalities. 相似文献
235.
Three macrocyclic hexaamines 1 , 2 , and 4 , and the acyclic tetraamine 5 and hexaamine 6 have been synthesized. The hexaamines 1 , 2 , and 4 are ditopic coreceptor molecules containing two triamine subunits which may bind anionic substrates when protonated. The stability constants of the complexes between the protonated forms of the macrocyclic polyamines and terminal dicarboxylates ?O2C?(CH2)m- CO2? as well as amino-acid and dipeptide dicarboxylates have been determined by pH-metric measurements. Around neutral pH, 1 and 2 give mainly complexes of the fully protonated species 1 ·6H+ and 2 ·6H+, whereas 4 yields predominantly complexes of 4 ·5H+ and 4 ·4H+. The stability sequences of the complexes formed indicate preferential binding of the dianionic substrates whose length is compatible with the separation of the triammonium binding subunits in the protonated receptor molecules 1 , 2 , and 4 . This selectivity pattern corresponds to a process of linear molecular recognition based on ditopic binding between the two ammonium subunits of the coreceptor and the terminal carboxylates of the substrate of complementary length. The complexes of the acyclic ligands 5 and 6 are much weaker and much less selective, indicating a marked macrocyclic effect on both stability and selectivity of binding, i.e. on recognition. 相似文献
236.
María Virginia Mirífico José Alberto Caram Oscar Enrique Piro Enrique Julio Vasini 《Journal of Physical Organic Chemistry》2007,20(12):1081-1087
The first nucleophilic addition of an inorganic nucleophile (cyanide) to the activated, rigid, α‐diazomethine groups of a 1,2,5‐thiadiazole 1,1‐dioxide is reported here. An α‐amino nitrile and a bis α‐amino nitrile derivatives were obtained in good yields (62 and 98%, respectively) and characterized by spectroscopic, analytical, and single crystal X‐ray diffraction techniques. The course of the reaction, followed by cyclic voltammetry (CV), showed that cyanide adds to only one of the two C?N double bonds of the thiadiazole, forming an anion from which an N‐methyl derivative was obtained. Adequate concentrations of cyanide and methyl iodide (MeI) produced directly the bis α‐amino nitrile derivative. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
237.
Adler J Becker JJ Blaylock GT Bolton T Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Dorfan DE Dubois GP Duncan AL Eigen G Einsweiler KF Eisenstein BI Freese T Gladding G Grab C Grancagnolo F Hamilton RP Hauser J Heusch CA Hitlin DG Izen JM Köpke L Li A Lockman WS Mallik U Matthews CG Mir R Mockett PM Mozley RF Nemati B Odian A Parrish L Partridge R Perrier J Pitman D Plaetzer SA Richman JD Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Simopoulos C 《Physical review letters》1988,60(2):89-92
238.
Bolton T Brown JS Bunnell KO Burchell M Burnett TH Cassell RE Coffman D Coward DH Coyle P DeJongh F Drinkard J Dubois GP Eigen G Eisenstein BI Freese T Gatto C Gladding G Heusch CA Hitlin DG Izen JM Kim PC Labs J Li A Lockman WS Mallik U Matthews CG Mir R Mockett PM Odian A Parrish L Pitman D Richman JD Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Stockdale IE Toki W Tripsas B Wang MZ Weinstein AJ Weseler S Willutzki HJ Wisniewski WJ Xu R Zhu Y 《Physical review letters》1992,69(9):1328-1331
239.
Coffman D DeJongh F Dubois GP Eigen G Hitlin DG Matthews CG Richman J Weinstein AJ Wisniewski WJ Zhu Y Bolton T Bunnell KO Cassell RE Coward DH Kim PC Labs J Odian A Pitman D Schindler RH Toki W Wasserbaech S Drinkard JJ Gatto C Heusch CA Lockman WS Sadrozinski HF Scarlatella M Schalk TL Seiden A Xu R Eisenstein BI Freese T Gladding G Izen JM Stockdale IE Tripsas B Mallik U Wang MZ Brown JS Burnett TH Li AD Mir R Mockett PM Nemati B Parrish L Willutzki H 《Physical review letters》1992,68(3):282-285
240.
Mohammad Amin Mir 《Journal of Dispersion Science and Technology》2018,39(8):1121-1125
Spectrophotometry is employed to study the effect cetyltrimethylammonium bromide (CTAB) and bis(cetyldimethylammonium)butane dibromide (C16C4C16Br2) on the activity of xanthine oxidase (XO), a key enzyme in purine metabolism, at pH 7.4 and 25°C. The spectrophotometric results revealed that the Gemini surfactant interact strongly with the XO than its conventional single chain counterpart and unfold it to a greater extent as compared to CTAB. The effectiveness of the Gemini in interacting/unfolding the XO are justified owing to peculiar structural features of C16C4C16Br2 owing to the presence of two charged headgroups and two hydrophobic tails and hence enhanced competence for electrostatic and hydrophobic interactions. 相似文献