Nukleofilikyvystä

Nukleofilikyvystä, often shortened to nucleophilicity, refers to the ability of a chemical species to donate an electron pair to form a new covalent bond. This species is known as a nucleophile, meaning "nucleus loving." Nucleophiles are typically electron-rich and seek out positively charged or electron-deficient centers, which are called electrophiles. The strength of a nucleophile is not a fixed property but depends on the reaction conditions, particularly the solvent and the nature of the electrophile.

Factors influencing nucleophilicity include charge, electronegativity, solvation, and steric hindrance. Negatively charged species are generally stronger nucleophiles than their neutral counterparts because they have a greater electron density. Electronegativity plays a role in polar protic solvents, where less electronegative atoms are better nucleophiles as their electron pairs are less tightly held. In contrast, in polar aprotic solvents, nucleophilicity often correlates with basicity. Steric hindrance, the crowding around the atom that would form the bond, can reduce nucleophilicity as it makes it harder for the nucleophile to approach the electrophile.

Common examples of nucleophiles include hydroxide ions (OH-), alkoxide ions (RO-), amines (RNH2), thiols (RSH), and carbanions. The concept of nucleophilicity is fundamental to understanding many organic reactions, such as nucleophilic substitution and nucleophilic addition.