دانلود کتاب جهت گیری ها و پیشرفت های جدید کاتالیز سوپرامولکولی

Catalysis concerns the phenomenon of a substance, the catalyst, that accelerates a chemical reaction. More precisely, a catalyst is a substance (inorganic, organic, biological) that enhances the rate by which a reaction approaches equilibrium without itself being permanently incorporated. By definition, the catalyst will do so a number of times (the turnover number, TON) within a certain time, expressed as turnover frequency (TOF). A catalyst lowers the free energy barrier of a reaction by interacting with the substrates and bringing them together (if more than one reactant is involved). Catalyzed intramolecular reactions and simple substitution reactions may follow the same, if accelerated, pathway as the uncatalyzed reaction, but especially metal catalysts and organocatalysts may follow a completely different pathway. Selectivity is an important additional property of a catalyst system, and this is achieved by a preferential acceleration of the pathway that leads to the desired product.