sulfonaatio

Sulfonaatio is a chemical reaction where a sulfonic acid group (R-SO3H) is introduced into an organic molecule. This process is often achieved by reacting the organic substrate with a sulfonating agent. Common sulfonating agents include concentrated sulfuric acid (H2SO4), fuming sulfuric acid (oleum, a solution of sulfur trioxide in sulfuric acid), and chlorosulfonic acid (ClSO3H). The specific agent and reaction conditions depend on the nature of the organic substrate and the desired outcome.

Sulfonation is a type of electrophilic aromatic substitution when applied to aromatic compounds. In this case, the electrophile is typically sulfur trioxide (SO3) or a related species generated from the sulfonating agent. The reaction involves the attack of the electron-rich aromatic ring on the electrophile, leading to the formation of a sigma complex, followed by the loss of a proton to regenerate aromaticity and attach the sulfonic acid group. For non-aromatic compounds, the mechanism can vary, sometimes involving free radical pathways or other addition reactions.

Sulfonic acids and their derivatives are important intermediates and end products in various industrial applications. They are used in the production of detergents, dyes, pharmaceuticals, and ion-exchange resins. The sulfonic acid group is strongly acidic and highly polar, which imparts water solubility and surfactant properties to molecules. This makes sulfonated compounds valuable in applications where solubility and surface activity are crucial. The reversibility of sulfonation, particularly for aromatic compounds, is also a key feature, allowing for desulfonation under specific conditions, which can be useful in multi-step organic syntheses.