The first century of isocyanide chemistry, which was then still a rather empty part of Organic Chemistry, began in 1859. In 1958 isocyanides became generally available by dehydration the formylamines. One year later the four component reaction of isocyanides (U-4CR) was introduced. This one-pot reaction is accomplished just by mixing amines, carbonyl compounds, suitable acids and isocyanides. Most chemical reactions have their own ”scope and limitation”, whereas the U-4CR can convert almost all combinations of educts into their products. Until 1995 this chemistry was moderately used, but since then a new era of the U-4CR and its unions with further reactions have become increasingly popular, particularly as libraries. In industry this chemistry became one of its most often used methods of finding new desirable products. In contrast to most other areas of chemistry, isocyanide chemistry is not yet exhausted and still much progress can be expected there.

A growing number of products, including many heterocycles, can be prepared by the one‐pot MultiComponent Reactions (MCRs) just by mixing three or more educts, and in many cases practically quantitative yields of pure products can be obtained. The 3CR by α‐aminoalkylations of nucleophiles began in the middle of the last century, and the syntheses of heterocycles by MCRs of three and four components were introduced by Hantzsch in the 1880s. The MCRs of the isocyanides with four and more educts began in 1959, and their compound libraries were mentioned since 1961. However, only since 1995 the often automated one‐pot chemistry of the MCR of the isocyanides is used extensively. If a chemical compound can be prepared by a sequence of two component reactions or a suitable MCR, the latter is always a superior procedure. The U‐4CR can be combined with other chemical reactions and MCRs as one‐pot reactions of n > 4 components, and such unions even have a much greater variety of structurally and stereochemically different products. The educts and products of Ugi‐type MCRs are more variable than those of all previous chemical reactions and other MCRs. Due to the progress in screening and automation processes in the last few years, many new compounds have been formed and investigated more rapidly than ever before. The search for new desirable products can be accomplished more than 10,000 times faster than by the older conventional methods. The now popular chemistry of the MCRs of the isocyanides fills the since long empty part of organic chemistry.

An anaerobic mixed culture enriched over 16 transfers (1/10) from Saale river sediment reductively dehalogenated 1,2,4- and 1,2,3-trichlorodibenzo-p-dioxin (TrCDD) to di- and monochlorinated congeners in the presence of pyruvate (or lactate) and fumarate as cosubstrates. Besides TrCDD, tetrachloroethene and 1,2,3-trichlorobenzene were dechlorinated. Dioxin dehalogenation was sensitive to pasteurization, but was not remarkably influenced by inhibitors of methanogens, sulfate-reducing bacteria or Gram-positive bacteria. The rate of 1,3-dichlorodibenzo-p-dioxin formation increased with rising initial concentrations of 1,2,4-TrCDD (1-250 microM) from 0.05 to 5.4 micromol l(-1) day(-1). Two isolates, belonging to Sulfurospirillum and Trichococcus, did not show reductive dehalogenation. 16S rDNA-targeted methods further revealed the presence of Acetobacterium, Desulfitobacterium, Desulfuromonas and Dehalococcoides. Nested polymerase chain reaction (PCR) indicated the presence of Dehalococcoides in highest most probable number (MPN) dilutions that were positive for dioxin dechlorination.

Organic chemistryOrganic chemistry Z 0200The Chemistry of Isocyanides, Their Multicomponent Reactions and Their Libraries -[120 refs.]. -(UGI, L.; WERNER, B.; DOEMLING, A.; Molecules 8 (2003) 1, 53-66; Inst. Org. Chem.

COMMUNICATIONSwhich allows structural information to be deduced from a measured vibrational spectrum. Strong hydrogen bonds with short 0-0 distances correlate with long, weakened 0 -H covalent bonds and low hydrogen stretching vibrations. If the 0-0 distance is increased. the length ofthe covalent bond approaches its unperturbed value approximately exponentially; the 0 -H stretching vibration increases almost linearly as the length of the covalent bond decreases. Aluminum-rich zeolites differ from their aluminum-poor counterparts both in their IR spectra and in their rea~tivity.'~. 16] In particular, the highest peak at 3500 cm-' seems to vanish as the Si:AI ratio approaches its lower limit of 1 ; 1. Therefore we investigated the interaction of methanol with two acid sites simultaneously. We find that the hydrogen bond between the methanol proton H, and an oxygen adjacent to another aluminum atom is shortened by about 5% and is therefore stronger than the hydrogen bond formed with an isolated acid site. Preliminary molecular dynamics simulations of I ps reveal a downward shift of the H,-0 vibration (located at 3500cm-' for the methanol hydroxyl group adsorbed on an isolated acid site) of roughly 400cm-', which could explain the disappearance of the former absorption band. However, it should be noted that aluminum-rich zeolites exhibit a substantially richer variety of structures for acid-site centers and adsorption complexes than aluminum-poor zeolites, a fact that has not yet been explored exhaustively.We studied sodalite to unravel processes that should also be relevant for the more complex zeolites actually used in technologically relevant processes. Therefore we should discuss to what extent our results apply to zeolites other than sodalite. We expect that the essential features of structure A are rather independent of the zeolite, as the tetrahedral angle on the Si and A1 atoms is largely conserved. Structure B, however, depends strongly on the local structure. Since it depends on the proximity of distant oxygen atoms, this structure can only occur in sufficiently small or highly deformed larger rings. Rings consisting of four atoms with tetrahedral coordination cannot be bridged, because the acid-site protons point outward. Since the structures A and B have similar vibrational patterns, we expect only quantitative changes in the IR spectra for zeolites that cannot form structure B. The largest deviations in the IR spectra will occur in the lower part (see Fig. 3), because this part is most sensitive to the strength of bond of the acid-site proton.Our computer experiments predicted adsorption structures of methanol in zeolites which, for the first time, are consistent with the available experimental data. This information forms the basis for the understanding of a large class of zeolite-catalyzed reactions. We have applied a theoretical approach t o zeolite chemistry, which allows us to study with a high level of accuracy dynamic behavior of molecules in zeolites at finite temperatures without the limitatio...