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1.
Molecules ; 29(14)2024 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-39064853

RESUMEN

Tetroxane derivatives are interesting drugs for antileishmaniasis and antimalaric treatments. The gas-phase thermal decomposition of 3,6,-dimethyl-1,2,4,5-tetroxane (DMT) and 3,3,6,6,-tetramethyl-1,2,4,5-tetroxane (acetone diperoxide (ACDP)) was studied at 493-543 K by direct gas chromatography by means of a flow reactor. The reaction is produced in the injector chamber at different temperatures. The resulting kinetics Arrhenius equations were calculated for both tetroxanes. Including the parent compound of the series 1,2,4,5-tetroxane (formaldehyde diperoxide (FDP)), the activation energy and frequency factors decrease linearly with the number of methyl groups. The reaction mechanisms of ACDP and 3,6,6-trimethyl-1,2,4,5-tetroxane (TMT) decomposition have been studied by means of the DFT method with the BHANDHLYP functional. Our calculations confirm that the concerted mechanism should be discarded and that only the stepwise mechanism occurs. The critical points of the singlet and triplet state potential energy surfaces (S- and T-PES) of the thermolysis reaction of both compounds have been determined. The calculated activation energies of the different steps vary linearly with the number of methyl groups of the methyl-tetroxanes series. The mechanism for the S-PES leads to a diradical O···O open structure, which leads to a C···O dissociation in the second step and the production of the first acetaldehyde/acetone molecule. This last one yields a second C···O dissociation, producing O2 and another acetone/acetaldehyde molecule. The O2 molecule is in the singlet state. A quasi-parallel mechanism for the T-PES from the open diradical to products is also found. Most of the critical points of both PES are linear with the number of methyl groups. Reaction in the triplet state is much more exothermic than the singlet state mechanism. Transitions from the singlet ground state, S0 and low-lying singlet states S1-3, to the low-lying triplet excited states, T1-4, (chemical excitation) in the family of methyl tetroxanes are also studied at the CASSCF/CASPT2 level. Two possible mechanisms are possible here: (i) from S0 to T3 by strong spin orbit coupling (SOC) and subsequent fast internal conversion to the excited T1 state and (ii) from S0 to S2 from internal conversion and subsequent S2 to T1 by SOC. From these experimental and theoretical results, the additivity effect of the methyl groups in the thermolysis reaction of the methyl tetroxane derivatives is clearly highlighted. This information will have a great impact for controlling these processes in the laboratory and chemical industries.

2.
Molecules ; 29(8)2024 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-38675580

RESUMEN

The presence of antibiotics in soils is increasing drastically in last decades due to the intensive farming industry and excessive human consumption. Clay minerals are one of the soil components with great adsorption capacity for organic pollutants. The study of interactions between antibiotics and mineral surfaces will give us scientific knowledge of these pollutants through soils. In this work, we study the adsorption of the antibiotic ciprofloxacin in the clay mineral fraction of soils from the Argentinian zone of Santa Rosa (Corrientes), in a collaborative research of experiments and atomistic modelling calculations of the intercalation of ciprofloxacin in the interlayer space of montmorillonite. Adsorption and desorption isotherms were performed and compared with different isotherm models. Additionally, enthalpy, entropy, and free energy were determined from equilibrium constants at a function of temperature. All these experiments and calculations lead to the conclusions that two adsorption types of ciprofloxacin are found on clay minerals: one weakly sorbed that is released during the desorption experiments, and other one strongly joined that remains in the soil.

3.
Acta toxicol. argent ; 9(2): 86-91, dic. 2001. ilus, tab
Artículo en Español | LILACS | ID: lil-356503

RESUMEN

El Senecio grisebachii es una planta de amplia distribución en el nordeste argentino que causa intoxicaciones en animales. En nuestro trabajo se alimentaron ratones con flores y hojas secas (20 por ciento de la ración) El vegetal causó intoxicación que se manisfestó por cambios en el comportamiento, perdida de peso y la histopatología revelò megalocitos y degeneración hidrópìca en zona centro lobulillar y periportal con mayor tiempo de consumo del vegetal. De distintas partes del vegetal se aislaron compuestos volátiles aún no detectados en esta planta, analizados por cromatografía gaseosa e identificados por espectrometría de masas. Los componentes identificados fueron: indol, b-mirceno, o-cimeno, ylangeno, cariofileno y a-cariofileno, que podrían sumarse a los tóxicos ya conocidos, los alcaloides pirrolizidinicos.


Asunto(s)
Ratones , Cromatografía de Gases/instrumentación , Hígado/lesiones , Ratones , Senecio
4.
Acta toxicol. argent ; 9(2): 86-91, dic. 2001. ilus, tab
Artículo en Español | BINACIS | ID: bin-4903

RESUMEN

El Senecio grisebachii es una planta de amplia distribución en el nordeste argentino que causa intoxicaciones en animales. En nuestro trabajo se alimentaron ratones con flores y hojas secas (20 por ciento de la ración) El vegetal causó intoxicación que se manisfestó por cambios en el comportamiento, perdida de peso y la histopatología revelò megalocitos y degeneración hidrópýca en zona centro lobulillar y periportal con mayor tiempo de consumo del vegetal. De distintas partes del vegetal se aislaron compuestos volátiles aún no detectados en esta planta, analizados por cromatografía gaseosa e identificados por espectrometría de masas. Los componentes identificados fueron: indol, b-mirceno, o-cimeno, ylangeno, cariofileno y a-cariofileno, que podrían sumarse a los tóxicos ya conocidos, los alcaloides pirrolizidinicos. (AU)


Asunto(s)
Ratones , Senecio/efectos adversos , Senecio/toxicidad , Ratones , Hígado/lesiones , Cromatografía de Gases/instrumentación
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