Wyniki wyszukiwania - BazTech

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Niskotemperaturowa katalityczna redukcja dwutlenku węgla : elektrochemiczna konwersja do prostych związków chemicznych

Rutkowska Iwona A., Kulesza Paweł J.

Wiadomości Chemiczne

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2024

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[Z] 78, 7-8

749--765

EN

Electrochemical approaches are generally suitable for the low-temperature CO2- conversion to carbon-based simple organic fuels or utility chemicals. Different concepts of utilization, including nanostructuring, hybridization, admixing, preconditioning, modification or functionalization of various catalytic systems for catalytic electroreduction of CO2 are elucidated, as well as important strategies to enhance the systems’ overall activity are discussed. Significance of experimental conditions, including temperature, pressure or concentration of CO2, a choice of electrolyte, its acidity, and presence of certain cations and anions are also addressed.

2

Computer simulations of the reactions of melamine with reactive solvents

Wianowski L., Hippe Z. S.

Polimery

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1999

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T. 44, nr 9

597-599

EN

Reactions with the reactive solvents, viz., hydroxymethyl derivatives of acetone, can help bring melamine into the solution. These solvents are synthesized by the exhaustive reaction of 1 mol acetone with 1-12 mols of formaldehyde. At the reactant ratio of 1:8 (by mols), adduct (II) is likely to form. Computer simulations using Ugi-Dugundji's matrix model [3] of constitutional chemistry, involving reaction enthalpies (calculated by Alien's algorithm [4] and correlation factors [5]), were used to decide between postulated reaction schemes A and B. The calculated reaction enthalpies -12 up to 6 kcal/mol, favor the reaction of (hydroxymethyl)mela-mine with (hydroxymethyl)acetone. The simulations confirmed that melamine could be dissolved in the reactive solvents according to scheme B which has been suggested in [2].

PL

Melaminę, której rozpuszczalność w typowych rozpuszczalnikach organicznych jest niewielka, można przeprowadzić w roztwór, stosując reakcje z tzw. rozpuszczalnikami reaktywnymi, np. z hydroksymetylowymi pochodnymi acetonu. Pochodne te można otrzymać w wyniku reakcji l mola acetonu z l-12 molami formaldehydu. W warunkach stosunku molowego reagentów 1:8 może utworzyć się addukt (II). Postulowano dwa mechanizmy reakcji melaminy z produktami przyłączenia formaldehydu do acetonu - A oraz B - i przeprowadzono symulacje komputerowe (model macierzowy Ugi-Dugundji [3], algorytm Allena [4] i współczynniki korelacji z [5]), aby rozstrzygnąć, który z nich jest bardziej prawdopodobny. Obliczono entalpie reakcji; przemawiają one na korzyść reakcji (hydroksylometylo)melaminy z (hydroksy-lometylo)acetonem (od -12 do 6 kcal/mol). Bardziej prawdopodobny jest schemat B [2]. Solubilizacja melaminy ma znaczenie w procesie sieciowania żywic melaminowych.

3

The thermal decomposition of certain metal chromates(VI)

Pisarska-Piesse B.B., Gontarz Z.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 9

2067-2078

EN

The thermal decomposition of M(I)2CrO4 (where M(I) = Li, Na, K, Rb, Cs, Ag, Tl), M(II)CrO4 (where M(II) = Mg, Ca, Sr, Ba), M(III)2(CrO4)3 (where M(III) = La, Nd) has been investigated. Mechanisms of invidual stages of the thermal decomposition have been proposed on the basis of morphological classification. The effect of cationic counterions on the decomposition of chromates (VI) is described.

4

Reaction of organic peroxides

Baj S., Chrobok A.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 7

1131-1147

EN

Reactivity of organic peroxy compounds, specially dialkyl peroxides is described. The knowlodge of chemical properties and reactivity of these substances is essential for the understanding of many practical aspects, e.g. the processes of ageing and explosion, waste management and biochemical processes. Peroxides reactions have been systematized using monomolecular and bimoleculr fragmentation. Among monomolecular reactions are homolytic and heterolytic decomposition; among bimolecular ionic and radical reactions.