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In chemistry, a reaction intermediate, or intermediate, is a molecular entity arising within the sequence of a stepwise chemical reaction. It is formed as the reaction product of an elementary step, from the reactants and/or preceding intermediates, but is consumed in a later step. It does not appear in the chemical equation for the overall ...
In chemistry, an activated complex represents a collection of intermediate structures in a chemical reaction when bonds are breaking and forming. The activated complex is an arrangement of atoms in an arbitrary region near the saddle point of a potential energy surface . [ 1 ]
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical reaction occurs. [1]A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of an overall chemical reaction.
When generated in a chemical reaction, it will quickly convert into a more stable molecule. Only in exceptional cases can these compounds be isolated and stored, e.g. low temperatures, matrix isolation. When their existence is indicated, reactive intermediates can help explain how a chemical reaction takes place. [1] [2] [3] [4]
At 298 K, a reaction with ΔG ‡ = 23 kcal/mol has a rate constant of k ≈ 8.4 × 10 −5 s −1 and a half life of t 1/2 ≈ 2.3 hours, figures that are often rounded to k ~ 10 −4 s −1 and t 1/2 ~ 2 h. Thus, a free energy of activation of this magnitude corresponds to a typical reaction that proceeds to completion overnight at room ...
Another example is the unimolecular nucleophilic substitution (S N 1) reaction in organic chemistry, where it is the first, rate-determining step that is unimolecular. A specific case is the basic hydrolysis of tert-butyl bromide (t-C 4 H 9 Br) by aqueous sodium hydroxide. The mechanism has two steps (where R denotes the tert-butyl radical t-C ...
In chemistry, a nitrene or imene (R−:Ṅ·) is the nitrogen analogue of a carbene. The nitrogen atom is uncharged and monovalent, [1] so it has only 6 electrons in its valence level—two covalent bonded and four non-bonded electrons. It is therefore considered an electrophile due to the unsatisfied octet.
In chemistry, a concerted reaction is a chemical reaction in which all bond breaking and bond making occurs in a single step. Reactive intermediates or other unstable high energy intermediates are not involved. [1] [2] Concerted reaction rates tend not to depend on solvent polarity ruling out large buildup of charge in the transition state.