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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 this type of substitution reaction, one group of the substrate participates initially in the reaction and thereby affects the reaction. A classic example of NGP is the reaction of a sulfur or nitrogen mustard with a nucleophile, the rate of reaction is much higher for the sulfur mustard and a nucleophile than it would be for a primary or secondary alkyl chloride without a heteroatom.
The carbonyl center in thioesters is more reactive toward amine than oxygen nucleophiles, giving amides: Thioesters are components of the native chemical ligation method for peptide synthesis. This reaction is exploited in native chemical ligation, a protocol for peptide synthesis. [8] In a related reaction, thioesters can be converted into ...
A sulfur nucleophile improved the enzymes transferase activity (sometimes called subtiligase). Selenium and tellurium nucleophiles converted the enzyme into an oxidoreductase. [51] [52] When the nucleophile of TEV protease was converted from cysteine to serine, it protease activity was strongly reduced, but was able to be restored by directed ...
Also, because the intermediate is partially bonded to the nucleophile and leaving group, there is no time for the substrate to rearrange itself: the nucleophile will bond to the same carbon that the leaving group was attached to. A final factor that affects reaction rate is nucleophilicity; the nucleophile must attack an atom other than a hydrogen.
In 1962, Edwards and Pearson (the latter of HSAB theory) introduced the phrase alpha effect for this anomaly. He offered the suggestion that the effect was caused by a transition state (TS) stabilization effect: on entering the TS the free electron pair on the nucleophile moves away from the nucleus, causing a partial positive charge which can be stabilized by an adjacent lone pair as for ...
Thiol with a blue highlighted sulfhydryl group.. In organic chemistry, a thiol (/ ˈ θ aɪ ɒ l /; [1] from Ancient Greek θεῖον (theion) 'sulfur' [2]), or thiol derivative, is any organosulfur compound of the form R−SH, where R represents an alkyl or other organic substituent.
This is an accepted version of this page This is the latest accepted revision, reviewed on 6 January 2025. This article is about the chemical element. For other uses, see Sulfur (disambiguation). Chemical element with atomic number 16 (S) Sulfur, 16 S Sulfur Alternative name Sulphur (pre-1992 British spelling) Allotropes see Allotropes of sulfur Appearance Lemon yellow sintered microcrystals ...