lisäysreaktiota

Lisäysreaktio, known in English as an addition reaction, is a fundamental type of organic chemical reaction. In this process, two or more molecules combine to form a single, larger molecule. This typically occurs when a double or triple bond in an unsaturated molecule breaks, allowing new atoms or groups to be added to the carbon atoms that were part of the multiple bond.

A classic example of a lisäysreaktio is the addition of hydrogen to an alkene, a reaction known as hydrogenation. Here, a hydrogen molecule (H2) adds across the carbon-carbon double bond of the alkene, resulting in the formation of a saturated alkane. Another common type involves the addition of halogens, such as bromine (Br2), to alkenes, forming dihaloalkanes.

Lisäysreaktiot are crucial in organic synthesis as they allow for the modification of functional groups and the construction of more complex molecules from simpler starting materials. They are characteristic of molecules containing pi bonds, such as alkenes and alkynes, where the electron-rich nature of the pi bond makes it susceptible to attack by electrophiles. The regiochemistry and stereochemistry of addition reactions are important considerations and are often predictable based on the nature of the reactants and reaction conditions. This type of reaction is also observed in inorganic chemistry, though the term is most commonly associated with organic transformations.