INVESTIGADORES
MOYANO Elizabeth Laura
congresos y reuniones científicas
Título:
Dictado de Conferencia: Flash Vacuum Pyrolysis: homogeneous and heterogeneous reactions. Applications and recent developments
Autor/es:
ELIZABETH L. MOYANO
Lugar:
Morgantown
Reunión:
Seminario; Seminarios del Department of Chemistry, Eberly College of Arts and Sciences; 2012
Institución organizadora:
Eberly College of Arts and Sciences, West Virginia University
Resumen:
Gas-phase thermal reactions have proven to be interesting methodologies
to study reaction mechanisms and for synthesis. Flash vacuum pyrolysis (FVP) is
one of these reactions and consists in submitting a molecule to the application
of high temperature (350-900ºC)
during a short period of time (~10-2 s). This important feature
allows getting kinetic as well as unstable products. FVP reactions are normally
clean, without solvent, so they normally involve carbenes, nitrenes, radicals
and concerted process. Thus, FVP can be used as a single step synthetic
procedure as well as a complement of a multistep route.
Applications of FVP as well as other gas phase thermal procedures to the
study of different heterocycles (pyrazoles, thiadiazoles, selenazoles,
triazines, azepines) have been explored. The most common reactions that afford
heterocycles are cyclizations of unsaturated compounds, ring fragmentations
including retro Diels-Alder reactions, isomerizations and extrusion of small
neutral molecules (N2, SO2, CO2).
An improvement of FVP reactions with the use of solid catalysts
(zeolites, MCM-41, scheelites) was also studied. These catalysts have two
effects, in some cases they lower the reaction temperature and in some others
there is a change of the reaction with formation of different products. These
results extend the possibilities of flash vacuum pyrolysis of a single
substrate.In a recent approach to combine the features of the gas phase thermal
reactions and the benefits of microwave irradiation, a new system denominated
Microwave Flash Pyrolysis was developed. This alternative methodology was used
to study the synthesis of seleno-compounds which are not conveniently prepared
by conventional reactions.