transition metal salts
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Author(s):  
Tatyana Rakitskaya ◽  
Tatyana Kiose ◽  
Lyudmila Raskola

The effect of the nature and concentration of d-metal salts attached to synthetic zeolites NaA and KA on the kinetic and stoichiometric parameters of the chemisorption-catalytic oxidation of sulphur dioxide with air oxygen at ambient temperature was studied. It was found that the adsorption capacity of NaA zeolite relative to SO2 is 100 times higher than that of KA zeolite; the time of protective action of NaA and KA zeolites increases upon modification with transition metal salts and with an increase of their content in the compositions. It was shown that the formation of inner and outer sphere complexes and the relationship between them is determined by the nature and concentration of metal ions and by the nature of the carrier. It was proven that the chemisorption-catalytic process ends with the oxidation of SO2 to H2SO4.


Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1811
Author(s):  
Aliya N. Mukhamed’yarova ◽  
Bulat I. Gareev ◽  
Danis K. Nurgaliev ◽  
Firdavs A. Aliev ◽  
Alexey V. Vakhin

Aluminum oxides and hydroxides are widely applied because of the great variety of their modifications. In particular, aluminum oxides and hydroxides are used in petrochemistry and oil refining. However, amorphous aluminum compounds have not been sufficiently studied due to the complexity of their synthesis and the problems encountered during their study. The study of amorphous aluminum compounds is hindered by the ambiguity of terminology. In this work, the structures of amorphous aluminum compounds prepared by different methods and the properties that determine their applications have been highlighted in detail. Amorphous aluminum compounds play both positive and negative roles in petrochemistry; however, in petroleum refining, amorphous compounds (without promoters and transition metal salts) demonstrate a promising catalytic performance in oil upgrading.


Cellulose ◽  
2021 ◽  
Author(s):  
Thomas Rosenau ◽  
Antje Potthast ◽  
Hubert Hettegger ◽  
Markus Bacher ◽  
Martina Opietnik ◽  
...  

AbstractSeveral literature reports describe the role of aqueous solutions of N-methylmorpholine-N-oxide monohydrate (NMMO) as a suitable medium for the generation of transition metal (nano)particles in or on cellulosic materials and further elaborate its role as a co-reactant of the transition metal salts that are reduced to the elemental metal. However, this would assign NMMO the role of a reductant, which is in contradiction of its obvious oxidative nature. In the present study, the exemplary cases of silver, gold, and platinum salts as the precursors of the respective metal (nano)particles in aqueous NMMO/cellulose mixtures were investigated. Naturally, NMMO did not act as a reducing agent in any case—this role was taken over by the frequently used NMMO stabilizer propyl gallate, or by cellulose itself, into which carbonyl and carboxyl groups were introduced. Also, hypochlorite—produced intermediately from chloride ions and subsequently undergoing disproportionation into chloride and chlorate—or transient N-methylene(morpholinium) ions generated from NMMO, which are in turn oxidized to formyl morpholide, can act as the corresponding reductants while the metal ions are reduced, depending on the reaction conditions. Apart from providing interesting mechanistic insights, the study points to the importance of a precise description of the composition of the chemical systems used, as well as the importance of seemingly inert auxiliaries, which turned out to be essential co-reactants in the metal (nano)particle generation. Graphic abstract


2021 ◽  
Vol 17 ◽  
pp. 2348-2376
Author(s):  
Sumana Mandal ◽  
Raju D Chaudhari ◽  
Goutam Biswas

The synthesis of complex cyclic compounds is extremely challenging for organic chemists. Many transition-metal-salt-mediated cyclizations are reported in literature. Hg(II) salts have been successfully employed in cyclizations to form complex heterocyclic and carbocyclic structures that are impossible to synthesize with other transition metal salts. In this review, we have summarized cyclization reactions that are performed with Hg(II) salts. These salts are also successfully applied in stoichiometric or catalytic amounts to form complex cyclic structures and natural products.


2021 ◽  
Vol 7 (8) ◽  
pp. 110
Author(s):  
Songjie Yang ◽  
Matteo Zecchini ◽  
Andrew Brooks ◽  
Sara Krivickas ◽  
Desiree Dalligos ◽  
...  

The syntheses of new BEDT-TTF derivatives are described. These comprise BEDT-TTF with one ethynyl group (HC≡C-), with two (n-heptyl) or four (n-butyl) alkyl side chains, with two trans acetal (-CH(OMe)2) groups, with two trans aminomethyl (-CH2NH2) groups, and with an iminodiacetate (-CH2N(CH2CO2−)2 side chain. Three transition metal salts have been prepared from the latter donor, and their magnetic properties are reported. Three tris-donor systems are reported bearing three BEDT-TTF derivatives with ester links to a core derived from benzene-1,3,5-tricarboxylic acid. The stereochemistry and molecular structure of the donors are discussed. X-ray crystal structures of two BEDT-TTF donors are reported: one with two CH(OMe)2 groups and with one a -CH2N(CH2CO2Me)2 side chain.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2314
Author(s):  
Kamil Peckh ◽  
Beata Orlińska

In this study, the transition metal (Co (II), Cu (II), and Mn (II)) salts of carboxylated carbon nanotubes were synthesized and characterized (the determined metal contents were in the range of 0.89–1.16%). The catalytic activity and the possibility for recovery and reuse of the obtained heterogeneous salts were then studied in the solvent-free oxidation of ethylbenzene with oxygen. The oxidation processes were carried out at 80 °C under atmospheric pressure in the presence of N-hydroxyphthalimide. The highest conversion of ethylbenzene, 27%, was obtained with a system consisting of the Cu (II) salt of the carboxylated carbon nanotubes, N-hydroxyphthalimide, and the azo initiator AIBN.


Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 554
Author(s):  
Athanasios Zarkadoulas ◽  
Ioanna Zgouleta ◽  
Nikolaos V. Tzouras ◽  
Georgios C. Vougioukalakis

Sustainable transformations towards the production of valuable chemicals constantly attract interest, both in terms of academic and applied research. C–H activation has long been scrutinized in this regard, given that it offers a straightforward pathway to prepare compounds of great significance. In this context, directing groups (DG) have paved the way for chemical transformations that had not been achievable using traditional reactions. Few steps, high yields, selectivity and activation of inert substrates are some of the invaluable assets of directed catalysis. Additionally, the employment of traceless directing groups (TDG) greatly improves and simplifies this strategy, enabling the realization of multi-step reactions in one-pot, cascade procedures. Cheap, abundant, readily available transition metal salts and complexes can catalyze a plethora of reactions employing TDGs, usually under low catalyst loadings—rarely under stoichiometric amounts, leading in greater atom economy and milder conditions with increased yields and step-economy. This review article summarizes all the work done on TDG-assisted catalysis with manganese, iron, cobalt, nickel, or copper catalysts, and discusses the structure-activity relationships observed, by presenting the catalytic pathways and range of transformations reported thus far.


2021 ◽  
Author(s):  
Venkata Swaroopa Datta Devulapalli ◽  
Mélissandre Richard ◽  
Tian-Yi Luo ◽  
Mattheus L. De Souza ◽  
Nathaniel L. Rosi ◽  
...  

The kinetics of hydrolysis of dimethyl nitrophenyl phosphate (DMNP), a simulant of the nerve agent Soman, was studied and revealed transition metal salts as catalysts.


Fire Safety ◽  
2020 ◽  
Vol 36 ◽  
pp. 101-107
Author(s):  
P. Pastuhov ◽  
V. Petrovskii ◽  
O. Lavrenyuk ◽  
B. Mykhalitchko

Introduction. In modern conditions, the combustibility of polymers plays a dominant role in the process of the appearance and spread of fires. This is because the extremely wide use of polymeric materials in all areas of the national economy. Due to the organic structure, the high content of carbon and hydrogen that make up the macromolecules of the polymers, they are extremely combustible. Combustion of polymers is accompanied by high temperature and flame propagation rate, as well as significant smoke generation and the release of a large number of toxic combustion products. Therefore, the search for new ways to reduce combustibility is one of the priority tasks in the creation and implementation of new polymer materials in various industries. Purpose. The aim of the work is the synthesis of fundamentally new complex compounds of transition metals, the study of their structure and properties, as well as predicting the possibility of their use to reduce the fire hazard of polymeric materials based on epoxy resins. Metods. Modern research methods are used in the work: X-ray diffraction, differential thermal and thermogravimetric analyzes, the method of quantum chemical calculations and IR spectroscopy. The ignition and self-ignition temperatures were determined by standard methods according to GOST 12.1.044-89 using metrologically certified equipment and calibrated measuring instruments. Results. By the direct interaction of the combustible organic amine pepa with inorganic salts of copper(II), a number of chelate complexes were obtained. By methods of x-ray phase analysis and IR spectroscopy, their structure was established. The results of quantum-chemical calculations of the complexation process showed that, as a result of the formation in the pepa–Cu(II) salt system, the chelate complexes [Cu(deta)H2O]SO4·H2O, [{Cu(deta)(H2O)(CO3)}2]·6H2O та [Cu(deta)(eda)]SiF6, the energy state of the chemically bonded pepa changes with respect to free molecules. In addition, the results of thermogravimetric studies and the measured ignition and self-ignition temperatures for pepa and complex compounds clearly showed that the process of bonding a combustible organic amine with a non-combustible inorganic salt into a solid complex ensures a decrease in the combustibility of nitrogen-containing hydrocarbon. All this is an extremely important prerequisite in the implementation of the complex mechanism of flame retardant action of transition metal salts. Conclusion. The results of the studies showed that complex compounds based on transition metal salts, and in particular copper(II), can be successfully used as flame retardants that can effectively reduce the fire hazard of nitrogen-containing synthetic polymers, including those based on epoxy resins.


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