ABSTRACT
In recent years, biofuels have been receiving significant attention because of their potential for decreasing carbon emissions and providing a long-term renewable solution to unsustainable fossil fuels. Currently, lactones are some of the alternatives being produced. Many lactones occur in a range of natural substances and have many advantages over bioethanol. In this study, the oxidation of alpha-angelica lactone initiated by ground-state atomic oxygen, O(3P), was studied at 298, 550, and 700 K using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at the Lawrence Berkeley National Lab (LBNL). Photoionization spectra and kinetic time traces were measured to identify the primary products. Ketene, acetaldehyde, methyl vinyl ketone, methylglyoxal, dimethyl glyoxal, and 5-methyl-2,4-furandione were characterized as major reaction products, with ketene being the most abundant at all three temperatures. Possible reaction pathways for the formation of the observed primary products were computed using the CBS-QB3 composite method.
Subject(s)
4-Butyrolactone/analogs & derivatives , Oxygen/pharmacology , Synchrotrons/instrumentation , 4-Butyrolactone/chemistry , Kinetics , Oxidation-Reduction , Oxygen/classification , TemperatureABSTRACT
The intramolecular Rauhut-Currier reaction creates a carbon-carbon bond between two tethered Michael acceptors. Previous asymmetric versions have relied on 1,4-additions of chiral nucleophilic catalysts. Herein, we investigate a novel strategy that involves the formation of electron rich dienamines as key intermediates. Our methodology provides an efficient entry to the iridoid framework.
Subject(s)
Carbon/chemistry , Oxygen/chemistry , Catalysis , Combinatorial Chemistry Techniques , Cross Reactions , Crystallography, X-Ray/methods , Cyclization , Hydrogen Peroxide/chemistry , Molecular Structure , Oxygen/classification , StereoisomerismABSTRACT
En este trabajo se hace una revisión del oxígeno hiperbárico como terapia metódica y racional que tiene muchas aplicaciones médicas . Los efectos beneficiosos, indicaciones y contraindicaciones son importantes ya que es una terapia bondadosa porque brinda oxígeno a los tejidos donde el mismo es escaso o nulo. La aceptación de la oxigenación hiperbárica (OBH) en el marco general de la medicina hospitalaria ha crecido progresivamente en cuanto a sus principales indicaciones. En la actualidad, la acumulación de experiencias clínicas y eperimentales permiten conocer con claridad su mecanismo de acción y sus limitaciones. la oxigenación hiperbárica ha estado mostrando mejoras en el tratamiento de traumatismos graves de los miembros, facilita la reparación de fracturas, reimplantación de partes corporales, lesiones por irradiación y leiones con procesos infecciosos de dificil resolución
