Lisäysreaktio

Lisäysreaktio, or addition reaction in English, is a fundamental type of chemical reaction where two or more molecules combine to form a larger molecule. This typically occurs when a multiple bond, such as a double or triple bond, is present in one of the reactant molecules. The pi bond in the multiple bond breaks, and the atoms from the other reactant molecule are added across the former multiple bond, forming new single bonds.

Addition reactions are characteristic of unsaturated organic compounds, particularly alkenes and alkynes, which contain carbon-carbon double and triple bonds, respectively. For example, the addition of hydrogen to an alkene in the presence of a catalyst (like palladium or platinum) is called hydrogenation. Similarly, halogens like bromine can be added to alkenes, a process known as halogenation. The addition of hydrogen halides, such as HCl or HBr, to alkenes follows Markovnikov's rule, which states that the hydrogen atom adds to the carbon atom with the greater number of hydrogen atoms already attached.

These reactions are crucial in organic synthesis, allowing for the transformation of simple molecules into more complex ones. They are employed in various industrial processes, including the production of plastics, pharmaceuticals, and petrochemicals. The type of addition reaction can vary, including electrophilic addition, nucleophilic addition, and radical addition, depending on the nature of the attacking species and the mechanism involved. Understanding addition reactions is key to comprehending the reactivity of many organic compounds.