Polyols

Polyols are a class of organic compounds characterized by multiple hydroxyl (-OH) groups. They are typically defined by the number of hydroxyl groups and their carbon skeleton, and can be aliphatic, cyclic, or aromatic. The term covers simple diols such as ethylene glycol, triols such as glycerol, and polyfunctional alcohols with more than three hydroxyls, such as pentaerythritol or sorbitol. Their chemical reactivity centers on the hydroxyl groups, which can participate in esterification, etherification, or urethane formation, enabling them to be building blocks for polymers and other products. They are generally polar and can be miscible with water depending on molecular size.

Polyols have wide use in polymer chemistry and consumer products. In industry, polyols react with di- or polyisocyanates to form polyurethane resins, foams, coatings, and elastomers. They may be classified as polyether polyols, polyester polyols, or other types depending on their backbone. In cosmetics and personal care, glycerin and propylene glycol serve as humectants and solvents. In food and medicine, sugar alcohols such as sorbitol, xylitol, and mannitol are used as low-calorie sweeteners and humectants, while some polyols act as excipients or stabilizers.

Production and safety: polyols are typically produced by polymerizing or modifying smaller alcohols or by reacting polyfunctional starting materials with alkylene oxides, or by esterification of diacids with diols. Processing hazards vary with the material; reactive polyurethane polyols require careful handling with isocyanates. Some polyols, notably certain glycol ethers, can be toxic in high doses; sugar alcohols can cause gastrointestinal effects at excessive intake. Environmental properties vary by type, with many polyesters being more readily biodegradable than polyether chemistries.