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Achemist,facedwiththeproblemofdeterminingthemechanismofachemical reaction, tries to identify a set of reactions that will account for the observed behavior:Ideally,asmallsetofknownreactionsshoulddescribeingreatdetail exactly what takes place at each stage of a chemical transformation. The fact that many reactions proceed in a stepwise fashion can most convincingly be demonstrated if intermediate species can be isolated and shown to proceed to the same products under otherwise identical reaction conditions. An - termediate is the reaction product of each of these steps, except for the last onethatformsthe?nalproduct. Someintermediatesarestablecompoundsin theirownright;someothers,however,aresoreactivethattheirisolationisnot possible. Occasionally, evidence for the existence of short-lived intermediates may be obtained, in particular by spectroscopic observation. The latter may - low a direct observation or an indirect inference from unusual phenomena occurring in the reaction products during in situ investigations of their c- responding chemical reactions. In NMR spectroscopy, for example, transient emissionandenhanced absorptionlinesmaybeobserved, andoneisinclined to believe that there is a universal and unambiguous reason for their appe- ance. Thisisnotnecessarilythecase,however,sincethisseeminglyidentical phenomenon may have a strikingly different origin: During free radical re- tions,aphenomenoncalledchemicallyinduced dynamicnuclear polarization (CIDNP) may give rise to virtually the same effect as occasionally observed duringhomogeneous(andpossiblyevenheterogeneous)hydrogenations:The latter phenomenon, called parahydrogen-induced polarization (PHIP), has a completely different physical basis. It was ?rst noticed twenty years later than CIDNP and occurs if there is an imbalance of the two spin isomers of symmetric molecules such as dihydrogen when hydrogenating unsaturated compoundsusingappropriatecatalysts. Thesetwoeffects,ifnotdifferentiated properly, can cause misinterpretations of reaction mechanisms, as occurred initially when their different origins had not yet been understood approp- ately.
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Heterogeneous catalysis --- 544.47 --- Catalysis. Catalytic reactions --- Heterogeneous catalysis.
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Catalysis --- Congresses --- 544.47 --- -Activation (Chemistry) --- Chemistry, Physical and theoretical --- Surface chemistry --- Catalysis. Catalytic reactions --- Congresses. --- -Catalysis. Catalytic reactions --- Catalysis - Congresses --- Catalysis, heterogeneous --- Catalysis, homogeneous --- Enzymes
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Catalysis --- Catalysis. --- Activation (Chemistry) --- Chemistry, Physical and theoretical --- Surface chemistry --- catalytic reactions --- enzymatic catalysis --- spectroscopic methods --- heterogeneous catalysis --- homogeneous catalysis
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Enzymes --- 544.47 --- 544.4 --- Biocatalysts --- Ferments --- Soluble ferments --- Catalysts --- Proteins --- Enzymology --- Catalysis. Catalytic reactions --- Chemical kinetics --- Acqui 2006
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The expression "Green Chemistry" is used to describe chemical processes that take into consideration sustainable development and environmentally improved products, as well as other aspects to make the reaction "cleaner". In recent years, this principle has become very important, with "Green Catalysis" a major topic within this field. Written by Roger A. Sheldon and his co-workers, this first book to focus on catalytic processes from the viewpoint of green chemistry presents every important aspect: - Numerous catalytic reductions and oxidations methods - Solid-acid and solid-base catalysis - C-C bond formation reactions - Biocatalysis - Asymmetric catalysis - Novel reaction media like e.g. ionic liquids, supercritical CO2 - Renewable raw materials.
katalyse --- Chemistry --- groene chemie --- Environmental chemistry --- Catalysis --- Industrial applications --- 544.47 --- Catalysis. Catalytic reactions --- duurzame ontwikkeling --- katalysatoren --- Environmental chemistry - Industrial applications
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Descriptive organic chemistry --- Hydrogenation --- Catalysts --- Hydrocarbons --- 544.47 --- 66.094.17 --- Organic compounds --- Catalytic agents --- Catalysis --- Chemical inhibitors --- Catalysis. Catalytic reactions --- Catalytic hydrogenation --- 66.094.17 Catalytic hydrogenation
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54-44 --- Catalysis --- Catalysts --- 544.47 --- Activation (Chemistry) --- Chemistry, Physical and theoretical --- Surface chemistry --- Catalytic agents --- Chemical inhibitors --- Catalysis. Catalytic reactions --- 54-44 Catalysts
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Asymmetric synthesis --- Catalysis --- Catalyse --- Asymmetric synthesis. --- Catalysis. --- 547.057 --- 544.47 --- #WSCH:LOSH --- Activation (Chemistry) --- Chemistry, Physical and theoretical --- Surface chemistry --- Asymmetric induction --- Induction, Asymmetric --- Synthesis, Asymmetric --- Asymmetry (Chemistry) --- Organic compounds --- Organic chemistry--?.057 --- Catalysis. Catalytic reactions --- Synthesis --- 547.057 Organic chemistry--?.057 --- CATALYSIS --- ASYMMETRIC SYNTHESIS --- HYDROGENATION --- ISOMERIZATION --- OXIDATION --- CARBONYLATION --- HYDROSILYLATION --- BOND --- RING CLOSURE --- CARBON-CARBON
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Superbly organized and of great pedagogic value, Spectroscopy in Catalysis describes the most important modern analytical techniques used to investigate catalytic surfaces. These include electron, ion, and vibrational spectroscopy, mass spectrometry, temperature-programmed techniques, diffraction, and microscopy. With the focus on practical use, rather than theory, each chapter presents current applications to illustrate the type of information that the technique provides and evaluates its possibilities and limitations, allowing selection of the best catalyst and the correct technique to solve.
Catalysis. --- Spectrum analysis. --- Catalyse --- Analyse spectrale --- Catalysis --- Spectrum analysis --- Catalysts --- Analysis --- 544.47 --- 543.42 --- Catalysis. Catalytic reactions --- Spectrum analysis. Spectroscopy. Spectrography. Spectrometry. Spectrophotometry. Fluorescence analysis --- 543.42 Spectrum analysis. Spectroscopy. Spectrography. Spectrometry. Spectrophotometry. Fluorescence analysis --- Catalysts - Analysis --- Catalyse. --- Catalyseurs --- Heterogene Katalyse. --- Reaktionsmechanismus. --- SCIENCE --- Spectroscopie. --- Spektroskopie. --- Analyse. --- Analysis. --- Chemistry --- Physical & Theoretical.
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