Vol. 106 No. 2 (2010)

Resumen: El presente artículo versa sobre un tipo especial de reacciones pericíclicas conocidas como reacciones o reordenamientos diotrópicos. Mostraremos los diferentes tipos de reacciones diotrópicas prestando especial interés a sus mecanismos de reacción más comunes. Además, para demostrar la gran utilidad que este tipo de transformaciones posee en síntesis orgánica y organometálica, presentaremos algunos ejemplos representativos orientados a la síntesis total de productos naturales.
Palabras clave: Reacciones pericíclicas, reordenamiento diotrópico, síntesis total, mecanismos de reacción, cálculos DFT.
Abstract: This article is focused on a special class of pericyclic reactions defined as dyotropic reactions or dyotropic rearrangements. The different types of these chemical transformations and their main reaction mechanisms shall be discussed. Furthermore, the great usefulness of dyotropic rearrangements in organic and organometallic synthesis will be proved by showing some representative applications of these processes in the total synthesis of natural products.
Keywords: Pericyclic reactions, dyotropic rearrangement, total synthesis, reaction mechanisms, DFT calculations.

Resumen: Hace aproximadamente 50 años Christian B. Anfinsen llevaba a cabo una serie de experimentos que resultaron ser contribuciones esenciales para la comprensión del fenómeno del plegamiento de proteínas. Los resultados obtenidos le permitieron proponer lo que ha terminado por conocerse como la Hipótesis de Anfinsen. Durante este tiempo la Biología se ha transformado radicalmente por la revolución que ha supuesto el desarrollo de la Biología Molecular. En el presente artículo se reflexiona sobre la propuesta de Anfinsen y se cuestiona su actual validez.
Palabras clave: Anfinsen, plegamiento de proteínas, biosíntesis de proteínas, ribosoma.
Abstract: Approximately 50 years ago Christian B. Anfinsen performed a series of experiments which represented seminal contributions to the understanding of the protein folding phenomenon. The results obtained allowed a proposal which has become to be known as the Anfinsen's Hypothesis. After all this time, Biology has been dramatically transformed by the development of the Molecular Biology revolution. This article is a reflection about Anfinsen's proposal as well as a challenge about its present validity.
Keywords: Anfinsen, protein folding, protein biosynthesis, ribosome.

Formamidines and ureas are of great interest as components of biologically active molecules, synthetic reagents and components of functional materials. The development of new compounds containing these functions is therefore of practical interest. In this sense, isonitriles and ureas have been found to undergo a condensation reaction in the presence of acid chlorides to give formamidine ureas, for which no other general synthetic routes currently exist. These compounds have emerged as powerful tunable electrophiles displaying a rich manifold of reactivity, which is governed primarily by the electron-donating power of the imine nitrogen substituents.

Keywords: Amidine, formamidine, urea, electrophile

Using a Lewis Carroll diagram the relationship between quantity and quality of publications is discussed.

Keywords: h index, Nobel prize, mathematical models

Resumen: La biosorción describe la eliminación, mediante materiales no vivos, de metales pesados en agua. Este proceso es barato ya que utiliza como biosorbentes materiales naturales como por ejemplo desechos de la agricultura (cáscara de naranja, cáscara de limón, salvado de soja, etc). Las partículas de biosorbente son empaquetadas en columnas de biosorción, que constituyen uno de los sistemas más efectivos para remoción continua de metales pesados. Se necesita más información sobre la biosorción para determinar la mejor combinación entre metal, tipo de biomasa y condiciones ambientales.
Palabras clave: Biosorción, metales pesados, biomasa no viva.
Abstract: Biosorption describes the elimination of heavy metals by a non living biomaterial from water solutions. This process is cheap because it uses natural materials as agricultural wastes (rice husk, orange peel, lemon peel, soya bran, etc) as bioadsorbent. Bioadsorbent particles can be packed into biosorption columns, which constitute one of the most effective artifact used for continuous heavy metal removal. More information is required about biosorption processes in order to determine best metal combinations, kind of biomass and environmental conditions.
Keywords: Biosorption, heavy metal, non living biomass.

This paper is an adaptation of the original one, which gained the "Salvador Senent” award, dealing with "Chemistry and Energy", announced by the Specialized Group in Didactic and History of Chemistry and sponsored by Forum of the Nuclear Spanish Industry. Its aim is to describe magnitudes, processes and devices of interest in order to understand some important contributions of Chemistry in electrical energy storage and production. The main −thermodynamic, kinetic, structural, reactivity and, definitely, chemical− principles implied in these processes are revised.

Keywords: energy, electrochemical devices, materials

Resumen: El presente artículo estudia un libro que ha formado a generaciones de químicos, particularmente en España donde estuvo vigente más de cincuenta años. "El Babor" apareció en 1935 y pasó por ocho ediciones. A lo largo de su dilatada historia experimentó una evolución profunda, a la que el profesor Ibarz contribuyó decisivamente. La obra pasó de ser un libro de texto típico a un libro de consulta, no menos valioso. En su etapa final se mantuvo sin perder sustancialmente las altas cotas de difusión alcanzadas.
Palabras clave: Historia de la química, enseñanza de la química, análisis de libros de texto, Joseph Babor, José Ibarz.
Abstract: This article analyzes a book studied by generations of chemistry students and chemists, particularly in Spain, where it was used for more than fifty years. "El Babor" appeared in 1935 and went through eight editions. Throughout its long history, the book underwent significant changes to which Professor Ibarz contributed decisively. During this time the book evolved from a conventional textbook to a valuable reference book. Even in its final phase, it was still very popular, and was widely used throughout the Spanish- speaking world.
Keywords: History of chemistry, chemistry education, textbook analysis, Joseph Babor, José Ibarz.

Resumen: El 10 de mayo de 1910 fallecía en Roma uno de los químicos europeos más geniales. Había nacido 83 años antes en Palermo, cuando formaba parte del Reino de las Dos Sicilias. Comenzó los estudios de medicina para continuar con los de química. Cambió la bata de laboratorio por el fusil y se enroló en el ejército revolucionario que liberó a su patria del yugo de los Borbones. Con escasos medios y grandes dificultades nos legó la reacción que lleva su nombre y fue el precursor de la tabla periódica al determinar con gran precisión los pesos atómicos de los elementos químicos conocidos. Fue el gran triunfador del Congreso de Karlsruhe en 1860.
Palabras clave: Cannizzaro, químico, revolucionario, tabla periódica, Congreso de Karlsruhe.
Abstract: On May 10, 1910, died in Rome one of the most brilliant European chemist. He was born 83 years earlier in Palermo, when it was part of the Kingdom of the Two Sicilies. He began his medical studies to continue with chemistry. He changed the laboratory coat by a gun and joined the revolutionary army that liberated their country from the Bourbons' yoke. With limited resources and great difficulties bequeathed the reaction that bears his name and was the forerunner of the periodic table to determine very accurately the atomic weights of the known chemical elements. He was the big winner of the Karlsruhe Congress in 1860.
Keywords: Cannizzaro, chemist, revolutionary, periodic table, Karlsruhe Congress.