Contribución de las microondas en el desarrollo de la química verde, su descripción y aportación en procesos ambientalmente benignos

Abstract

The microwaves like way of energizing chemical reactions it has had a great acceptance on the part of very much scientific groups in the whole world. In our school the group led by the Dr. Eloy Vazquez Labastida has come being employed in the last 6 years at this area with excellent results. For those who in this work are summarized and they analyze many of the scientific information that have led to this technology to the levels that the environment has, the most important advances are outlined, focusing the work in the sense of knowing and analyzing the convergence between this tannic and the new technology. The oven of domestic microwave is an invention coincidencial, as many of that they have appeared along the history of the man. The one who was going to think that the fact happened to Percy Spencer who was working for a manufacturing plant of radars during 2 ª world war, would provide to him the information that would take him to the development of this type of instrumentation when he noticed of the heat build-up in an antenna of radar. In 1947 the first commercial unit appeared on the market for the food transformation. The first oven of domestic microwave of which knowledge is had was presented by the old north American company of domestic appliances Tappan-IEM in the year of 1955. Nowadays the sale of domestic economic ovens and his use they represent an annual multimillionaire market, nevertheless we must not confuse these articles with the new generation of companies dedicated to the manufacture of specific equipments for investigation where the temperature and the pressure can be perfectly controlled. Numerous applications using the microwaves as way energizante they have appeared in last two decades principally for the dried one of different types of materials (rubbers, tobacco, leather, sugar, coffee, grains, etc ...), in processes and treatment of elastomers, vulcanization, extraction, polymerization, synthesis of medicaments and raw materials, besides his wide acceptance in the food processing industry and of process. The field of the organic chemistry represented with microwave, it is therefore a technology practically young woman. The first two publications, considered pioneers of the field appeared in 1986 and they are attributed to the investigators R. Gedye and R. J. Giguere. These authors described that several reactions in the organic chemistry that they were needing of a lot of time under traditional warming (burners, baths of oil, blankets of warming, etc. …) they were concluded in very short times using microwave (MW), as way of warming in only a few minutes and even seconds, when they were placed in closed containers (glass, quartz or teflón) in domestic ovens. If the viability of the procedure was evident, some explosions caused by the rapid development of discharges pressures generated inside the systems of reaction demonstrated, for what they were the principal aim of the first experiences brought in the scientific literature for multiple authors. The first brought experiences were directed the prevention of the above mentioned disadvantages and surer technologies were looked using equipments like that of reaction more sure with opened devices, using solvents, up to coming to the new options of reactions without solvent or in inert supports taking the technology towards the area of the called " Green Chemistry ". This procedure has showed interest in free reactions of solvent, is a more economic technology of rapid acceleration in the speed of the reaction and without the generation of secondary reactions or pollutant garbage. The aim of this work is to centre on the diverse fields of the use of this new technology and on the principal fields of the organic synthesis, trying to interpret by means of the analysis of the works that have appeared, to clarify not only the thermal phenomenon of the process, but also, since there are affected the speed and the energy of the reaction.