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Catalysis is ubiquitous in chemical industry of all kinds. [6] Estimates are that 90% of all commercially produced chemical products involve catalysts at some stage in the process of their manufacture. The term "catalyst" is derived from Greek καταλύειν, kataluein, meaning "loosen" or "untie".
In chemistry, a catalytic cycle is a multistep reaction mechanism that involves a catalyst. [1] The catalytic cycle is the main method for describing the role of catalysts in biochemistry, organometallic chemistry, bioinorganic chemistry, materials science, etc.
Typical catalysts are platinum, and redox-active oxides of iron, vanadium, and molybdenum. In many cases, catalysts are modified with a host of additives or promoters that enhance rates or selectivities. Important homogeneous catalysts for the oxidation of organic compounds are carboxylates of cobalt, iron, and manganese
In specific acid catalysis, protonated solvent is the catalyst. The reaction rate is proportional to the concentration of the protonated solvent molecules SH +. [6] The acid catalyst itself (AH) only contributes to the rate acceleration by shifting the chemical equilibrium between solvent S and AH in favor of the SH + species. This kind of ...
Two common modes of Lewis acid catalysis in reactions with polar mechanisms. In reactions with polar mechanisms, Lewis acid catalysis often involves binding of the catalyst to Lewis basic heteroatoms and withdrawing electron density, which in turn facilitates heterolytic bond cleavage (in the case of Friedel-Crafts reaction) or directly activates the substrate toward nucleophilic attack (in ...
The catalysts used for catalytic distillation are composed of different substances and packed onto varying objects. The majority of the catalysts are powdered acids, bases, metal oxides, or metal halides. These substances tend to be highly reactive which can significantly speed up the rate of the reaction making them effective catalysts. [3]
In chemistry, the term "turnover number" has two distinct meanings.. In enzymology, the turnover number (k cat) is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration [E T] for enzymes with two or more active sites. [1]
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...