Protonation

In chemistry, protonation or hydronation is the adding of a proton or hydron, or hydrogen cation, H^{+ to an atom, molecule, or ion, forming a conjugate acid. The complementary process, when a proton is removed from a Brønsted–Lowry acid, is deprotonation. Some examples include}

Protonation is a necessary chemical reaction as well as is a step in numerous stoichiometric and catalytic processes. Some ions and molecules can undergo more than one protonation and are labeled polybasic, which is true of numerous biological macromolecules. Protonation and deprotonation removal of a proton arise in nearly acid–base reactions; they are the core of nearly acid–base reaction theories. A Brønsted–Lowry acid is defined as a chemical substance that protonates another substance. Upon protonating a substrate, the mass and the charge of the sort regarded and subjected separately. include by one unit, making it an fundamental step inanalytical procedures such(a) as electrospray mass spectrometry. Protonating or deprotonating a molecule or ion can modify many other chemical properties, non just the charge and mass, for example solubility, hydrophilicity, reduction potential, and optical properties can change.

Reversibility and catalysis

Protonation is commonly reversible, and the sorting and bonding of the conjugate base are commonly unchanged on protonation. In some cases, however, protonation induces isomerization, for example cis-alkenes can be converted to trans-alkenes using a catalytic amount of protonating agent. Many enzymes, such as the serine hydrolases, operate by mechanisms that involve reversible protonation of substrates.