Diolien

Diolien is a term used in chemistry to refer to diols, organic compounds that contain two hydroxyl groups (-OH) in the molecule. Diols are a subset of alcohols and can be categorized by the positions of their hydroxyl groups: vicinal diols (1,2-diols) have adjacent OH groups, while geminal diols (1,1-diols) have both OH groups on the same carbon. Geminal diols are generally unstable and exist mainly as hydrates in solution, with formaldehyde hydration giving methanediol as a simple example.

Nomenclature for diols follows the parent carbon skeleton with the diol descriptor, for example ethane-1,2-diol (ethylene glycol), propane-1,3-diol (trimethylene glycol), and 1,4-butanediol. Common diols include ethylene glycol, propylene glycol (1,2-propanediol), and 1,4-butanediol, while glycerol is a triol and thus not a diol.

Physically, diols are typically polar and form hydrogen bonds, leading to relatively high boiling points and good water solubility compared with nonpolar hydrocarbons. They are versatile in applications due to their bifunctionality: diols act as solvents, intermediates in organic synthesis, and as reactive building blocks in polymer chemistry.

Uses span antifreeze and heat-transfer fluids (ethylene glycol), solvents (ethylene glycol and others), and monomers or chain extenders in polyesters, polyurethanes, and various polymers. Some diols serve as plasticizers or processing aids in industrial formulations.

Reactions of diols include oxidation of vicinal diols to carbonyl compounds or cleavage to fragments by periodic acid, lead tetraacetate, or related reagents. Diols also participate in protection/deprotection strategies in synthesis and can be involved in redox or esterification chemistry.

Safety considerations vary by substance; some diols (notably ethylene glycol) are toxic if ingested, and standard chemical hygiene applies.