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A hydroxide ion acting as a nucleophile in an S N 2 reaction, converting a haloalkane into an alcohol. In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they ...
In chemistry, a nucleophilic substitution (S N) is a class of chemical reactions in which an electron-rich chemical species (known as a nucleophile) replaces a functional group within another electron-deficient molecule (known as the electrophile). The molecule that contains the electrophile and the leaving functional group is called the substrate.
the simple first-order rate law described in introductory textbooks. Under these conditions, the concentration of the nucleophile does not affect the rate of the reaction, and changing the nucleophile (e.g. from H 2 O to MeOH) does not affect the reaction rate, though the product is, of course, different. In this regime, the first step ...
In many nucleophilic reactions, addition to the carbonyl group is very important. In some cases, the C=O double bond is reduced to a C-O single bond when the nucleophile bonds with carbon. For example, in the cyanohydrin reaction a cyanide ion forms a C-C bond by breaking the carbonyl's double bond to form a cyanohydrin.
The nucleophile is polarised and oriented by the base, which is itself bound and stabilised by the acid. [24] Catalysis is performed in two stages. First, the activated nucleophile attacks the carbonyl carbon and forces the carbonyl oxygen to accept an electron pair, leading to a tetrahedral intermediate. The resulting build-up of negative ...
Strong acids catalyze the reaction by donating a proton to the carbonyl group, thus making it a more potent electrophile. Bases catalyze the reaction by removing a proton from the alcohol, thus making it more nucleophilic. The reaction can also be accomplished with the help of enzymes, particularly lipases (one example is the lipase E.C.3.1.1.3 ...
Synthesis of nucleosides involves the coupling of a nucleophilic, heterocyclic base with an electrophilic sugar. The silyl-Hilbert-Johnson (or Vorbrüggen) reaction, which employs silylated heterocyclic bases and electrophilic sugar derivatives in the presence of a Lewis acid, is the most common method for forming nucleosides in this manner.
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. [1] When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated.