Desarrollo de nueva metodología sintética basada en procesos térmicos y fotoquímicos de complejos de metal-carbenoide

La reaccion de complejos alcoxicromocarbenoide con iluros se ha estudiado empleando como reactivos sulfiliminas (iluros de tipo n=s) e iluros de azufre (iluros de tipo c=s). Este tipo de reacciones permite obtener, de una forma sencilla, imidatos, vinil eteres, y ciclopropanos. Adicionalmente, se ha observado una aceleración fotoquímica del proceso no descrita previamente. El segundo grupo de reacciones estudiadas se basa en la generación fotoquímica de cetenas a partir de complejos cromocarbenoide. La fotoquímica de complejos sililoxicromocarbenoide para obtener alfa-hidroxiamidas demuestra que pueden emplearse complejos inestables en este tipo de reacciones. La síntesis de complejos cromocarbenoide con grupos imino en su estructura, desconocidos hasta ahora, nos ha permitido obtener nuevas gamma-lactamas "anti-bredt", con interesantes propiedades estructurales: y espectroscopicas. Por ultimo, hemos aplicado la reaccion fotoquímica de complejos cromocarbenoide con iminas para sintetizar beta-lactamas c4- no sustituidas en una reaccion en dos pasos: fotocicloadicion y desulfuracion usando nib2. La síntesis de estos compuestos, cuya tipología esta presente en un buen numero de antibióticos, representa una de las aproximaciones mas eficaces, descritas hasta la fecha, a este tipo de compuestos.Depto. de Química OrgánicaFac. de Ciencias QuímicasTRUEpu

Decontamination of Diesel particles from air by using the Counterfog (R) system

The existence of particles with diameter under 10m in air is strongly correlated with respiratory diseases. These particles are profusely produced by heating systems, traffic, and Diesel engines creating a serious problem to modern cities. Natural mechanisms removing particles from the atmosphere are too slow to deal with the huge amount of particles daily released by human activity. The objective of this work is to measure the effectiveness of a new technology called Counterfog (R) to eliminate airborne particles. The results show that Counterfog (R) is able to wash out PM10, PM5, and PM2.5 Diesel-generated airborne particles quite efficiently.This work has been funded by the FP7-SEC-2012-1 program of the EU Commission under grant number 312804

Role of imine isomerization in the stereocontrol of the Staudinger reaction between ketenes and imines

Computational–experimental analysis has allowed determining that the stereochemistry of the Staudinger reaction between ketenes and imines is strongly associated with the nature of the imine, which affects the two steps of the reaction. The first step, namely the nucleophilic attack of the sp2-hybridized nitrogen atom of the imine on the sp-hybridized carbon atom of the ketene, is affected by the energetically accessible in situ isomerization patterns of the imine. The second step consists of a conrotatory electrocyclization of the zwitterionic intermediate formed in the previous step. This latter pericyclic step depends on the inward/outward torquoelectronic effects generated by the substituents of the imine. The impact of these factors on the stereochemistry of this reaction has been analyzed kinetically by numerical methods. The results of these simulations are compatible with the experimental results and support these conclusions

El animal como protagonista en los carnavales españoles

En número dedicado a: El Carnaval. Indice

Magnetic Gearboxes for Aerospace Applications

Magnetic gearboxes are contactless mechanisms for torque-speed conversion. They present no wear, no friction and no fatigue. They need no lubricant and can be customized for other mechanical properties as stiffness or damping. Additionally, they can protect structures and mechanisms against overloads, limitting the transmitted torque. In this work, spur, planetary and "magdrive" or "harmonic drive" configurations are compared considering their use in aerospace applications. The most recent test data are summarized to provide some useful help for the design engineer