591-22-0Relevant academic research and scientific papers
Catalyst-Free N-Deoxygenation by Photoexcitation of Hantzsch Ester
Cardinale, Luana,Jacobi Von Wangelin, Axel,Konev, Mikhail O.
supporting information, (2020/02/15)
A mild and operationally simple protocol for the deoxygenation of a variety of heteroaryl N-oxides and nitroarenes has been developed. A mixture of substrate and Hantzsch ester is proposed to result in an electron donor-acceptor complex, which upon blue-light irradiation undergoes photoinduced electron transfer between the two reactants to afford the products. N-oxide deoxygenation is demonstrated with 22 examples of functionally diverse substrates, and the chemoselective reduction of nitroarenes to the corresponding hydroxylamines is also shown.
Photorelease of Pyridines Using a Metal-Free Photoremovable Protecting Group
Dong, Zaizai,Fang, Xiaohong,Kou, Xiaolong,Tan, Weihong,Tang, Xiao-Jun,Wu, Yayun,Zhang, Zhen,Zhao, Rong,Zhou, Wei
supporting information, p. 18386 - 18389 (2020/08/24)
The photorelease of bioactive molecules has emerged as a valuable tool in biochemistry. Nevertheless, many important bioactive molecules, such as pyridine derivatives, cannot benefit from currently available organic photoremovable protecting groups (PPGs). We found that the inefficient photorelease of pyridines is attributed to intramolecular photoinduced electron transfer (PET) from PPGs to pyridinium ions. To alleviate PET, we rationally designed a strategy to drive the excited state of PPG from S1 to T1 with a heavy atom, and synthesized a new PPG by substitution of the H atom at the 3-position of 7-dietheylamino-coumarin-4-methyl (DEACM) with Br or I. This resulted in an improved photolytic efficiency of the pyridinium ion by hundreds-fold in aqueous solution. The PPG can be applied to various pyridine derivatives. The successful photorelease of a microtubule inhibitor, indibulin, in living cells was demonstrated for the potential application of this strategy in biochemical research.
Identification of intermediate compounds and photodegradation mechanisms of omeprazole under the system UV/O2
Leyva, Elisa,Moctezuma, Edgar,Baines, Kim M.,Noriega, Saúl,Pérez Flores, Francisco,Lara-Pérez, Carmen
, (2019/12/03)
The photodegradation of the proton pump inhibitor omeprazole (OME) in aqueous media with the system UV/O2 is presented. The photodegradation rate was assessed by HPLC and UV-vis spectroscopy, while the mineralization rate was obtained by TOC measurements. Degradation products were investigated by IR spectroscopy and GC-MS analysis. UV-vis absorbance and HPLC results indicated that OME is completely degraded within 3?minutes of irradiation. TOC analysis indicated that intermediates compounds are relatively easy to mineralize since 80% mineralization is achieved within 2?hours. IR studies demonstrated a rapid oxidation of OME leading to the formation of amines and both sulfonic and carboxylic acids. GC-MS data indicated that the initial photoproducts are derivatives of both benzimidazole and pyridine produced after the photochemical cleavage of the C–S bond. Plausible mechanisms for the direct and indirect degradation of OME are given. In the photochemical degradation of OME, many intermediate compounds are actually generated. Several of them were generated from hydroxyl radical reactions, but some of them resulted from rearrangements, reductive reactions, and through the formation of highly reactive intermediates such as pseudo carbene, thiooxirane, and sulfenamide.
Mesoporous Aluminosilicates in the Synthesis of N-Heterocyclic Compounds
Agliullin, M. R.,Bikbaeva, V. R.,Bubennov, S. V.,Filippova, N. A.,Gataulin, A. R.,Grigor’eva, N. G.,Kostyleva, S. A.,Kutepov, B. I.,Narender, Nama
, p. 733 - 743 (2020/02/25)
Abstract: The catalytic properties of samples of amorphous mesoporous aluminosilicate ASM with different Si/Al molar ratios (40, 80, 160) were studied in the synthesis of practically important pyridines (by the interaction of С2–С5 alcohols with formaldehyde and ammonia, cyclocondensation of acetaldehyde and propionic aldehyde with ammonia), dialkylquinolines and alkyltetrahydroquinolines (by reaction of aniline with C3, C4 aldehydes) and alkyldihydroquinolines (by interaction of aniline with ketones, acetone and acetophenone). It is found that mesoporous aluminosilicate ASM sample with a molar ratio of Si/Al = 40, which has the highest acidity among the studied samples, exhibits the highest activity and selectivity in these reactions.
Template-free synthesis of high degree crystallinity zeolite y with micro-meso-macroporous structure
Travkina,Agliullin,Filippova,Khazipova,Danilova,Grigor'Eva,Narender, Nama,Pavlov,Kutepov
, p. 32581 - 32590 (2017/07/07)
In this paper a new approach to the creation of a micro-meso-macroporous structure of Y zeolite was proposed. It was based on the selective crystallization into the integral cluster crystals of the preliminarily molded granules containing crystals of the zeolite in question and a porous binder matrix. The synthesized material was characterized by the high crystallinity degree of 95% and the volume of micro-, meso-, and macro-pores of 0.30, 0.15 and 0.15 cm3 g-1, respectively. It was shown that the Y zeolite with the hierarchical structure in H-form had the total acidity of about 830 μmol g-1 and revealed the high activity and selectivity in the synthesis of pyridines.
Crystalline and amorphous aluminosilicates with different pore structures for the synthesis of pyridines
Grigor'eva, Nellya G.,Filippova, Nadezhda A.,Agliullin, Marat R.,Kutepov, Boris I.,Narender, Nama
, p. 253 - 261 (2017/06/19)
The heterogeneous catalytic synthesis of pyridine and methylpyridines (picolines) was carried out by the reaction of ethanol with formaldehyde and ammonia over aluminosilicates with different acidic properties and textural characteristics: zeolite framework-type FAU in H-form with microporous (H-Y) and micro-meso-macroporous structure (H-Y-mmm) and mesoporous aluminosilicates, obtained by sol-gel synthesis in an alkaline medium (ASM-1) and under variable pH (ASM-2). It is shown that the highest catalytic activity is characteristic of ASM-2 (Si/Al = 40) with a narrow pore size distribution within the range 2 to 5 nm and containing strongly acidic bridging Si-OH-Al groups on the surface. The products of the reaction of ethanol with formaldehyde and ammonia on the catalysts studied are dominated by picolines; the maximum amount of picolines (60%) is formed on the H-Y-mmm and aluminosilicate ASM-2 samples.
Unsaturated aldehydes: a novel route for the synthesis of pyridine and 3-picoline
Luo, Cai-Wu,Chao, Zi-Sheng
, p. 54090 - 54101 (2015/06/30)
A novel reaction pathway was developed for the synthesis of pyridine and 3-picoline from the condensation of gas-phase acrolein dimethyl acetal or acrolein diethyl acetal and ammonia over various catalysts in a fixed-bed reactor. ZnO loaded on alkaline-acid sequentially-treated HZSM-5, namely ZnO/HZSM-5-At-acid, was prepared and employed in these reactions for the first time. 3-Picoline, without the generation of 4-picoline, was obtained from the condensation of acrolein dimethyl acetal and ammonia. The ZnO/HZSM-5-At-acid catalyst was proven to be the most promising catalyst relative to other catalysts in this study. The stability of the ZnO/HZSM-5-At-acid catalyst was remarkably higher than that of the ZnO/HZSM-5 catalyst. The catalysts were characterized using XRD, 27Al MAS NMR, XPS, UV-vis DRS, N2-physisorption, NH3-TPD and TG technologies and the results revealed that the pore structure, acidity and location of ZnO had great influence on the total yield of pyridine and 3-picoline, and the catalyst stability.
Amination of allyl alcohol to propionitrile over a Zn30Cr 4.5/γ-Al2O3 bimetallic catalyst via coupled dehydrogenation-hydrogenation reactions
Zhang, Yuecheng,Wei, Tianyu,Pian, Yanjie,Zhao, Jiquan
, p. 154 - 162 (2013/09/02)
A Zn30Cr4.5/γ-Al2O3 bimetallic catalyst that can perform coupled dehydrogenation and hydrogenation reactions was prepared for the amination of allyl alcohol to propionitrile. During the catalysis, the hydrogen derived from the dehydrogenation of the alcohol and imine acted as an in situ source for the hydrogenation of the carbon-carbon double bond. The catalyst exhibited good performance for the reaction at atmospheric ammonia pressure. The parameters that affect the catalyst performance were studied thoroughly, and an optimized process for synthesizing propionitrile from allyl alcohol and ammonia over the catalyst was obtained. Under the optimized conditions, the propionitrile yield was greater than 65%. The characterization results indicated that the dehydrogenation reaction mainly occurred on the Lewis acid sites and revealed that ZnAl 2O4 is the active species for the coupled dehydrogenation-hydrogenation reactions. Chromium doping of the γ-Al 2O3-supported zinc catalyst Zn30/γ- Al2O3 resulted in a decrease in the size of the ZnAl 2O4 crystallites, which was favorable for the dehydrogenation-hydrogenation reactions. The characterization results also revealed that the catalyst deactivation was due to carbon deposition on the catalyst during the catalytic run. The catalyst could be reactivated by blowing air into the reactor at a high temperature.
Acid-base responsive switching between 3+1 and 2+2 platinum complexes
Sooksawat, Dhassida,Pike, Sarah J.,Slawin, Alexandra M.Z.,Lusby, Paul J.
supporting information, p. 11077 - 11079 (2013/11/19)
We report that the acid-base induced changes to a cyclometallated platinum complex can be used to drive the exchange of accompanying ligands with different denticities.
Dissection of complex molecular recognition interfaces
Hunter, Christopher A.,Misuraca, Maria Cristina,Turega, Simon M.
supporting information; experimental part, p. 582 - 594 (2011/04/16)
The synthesis of a family of zinc porphyrins and pyridine ligands equipped with peripheral H-bonding functionality has provided access to a wide range of closely related supramolecular complexes featuring between zero and four intramolecular H-bonds. An automated UV/vis titration system was used to characterize 120 different complexes, and these data were used to construct a large of number of different chemical double mutant cycles to quantify the intramolecular H-bonding interactions. The results probe the quantitative structure-activity relationship that governs cooperativity in the assembly of complex molecular recognition interfaces. Specifically, variations in the chemical structures of the complexes have allowed us to change the supramolecular architecture, conformational flexibility, geometric complementarity, the number and nature of the H-bond interactions, and the overall stability of the complex. The free energy contributions from individual H-bonds are additive, and there is remarkably little variation with architecture in the effective molarity for the formation of intramolecular interactions. Intramolecular H-bonds are not observed in complexes where they are geometrically impossible, but there are no cases where excellent geometric complementarity leads to very high affinities. Similarly, changes in conformational flexibility seem to have limited impact on the values of effective molarity (EM). The major variation that was found for all of the 48 intramolecular interactions that were examined using double mutant cycles is that the values of EM for intramolecular carboxylate ester-phenol H-bonds (200 mM) are an order of magnitude larger than those found for phosphonate diester-phenol H-bonds (30 mM). The corresponding intermolecular phosphonate diester-phenol H-bonds are 2 orders of magnitude more stable than carboxylate ester-phenol H-bonds, and the large differences in EM may be due to some kind of compensation effect, where the stronger H-bond is harder to make, because it imposes tighter constraints on the geometry of the complex.
