polyhydroxy

Polyhydroxy refers to chemical compounds that contain more than one hydroxyl (-OH) group. In practice, the term is often used to describe polyols, a subset of alcohols with two or more hydroxyl groups. Polyhydroxy compounds are typically highly polar and capable of extensive hydrogen bonding, which influences their solubility, reactivity, and physical properties.

Common examples include glycerol (propane-1,2,3-triol) with three hydroxyls, ethylene glycol (ethylene diol) with two, and sugar alcohols such as sorbitol, xylitol, and mannitol, which are hexitols or pentitols. Carbohydrates like glucose and galactose are also polyhydroxylated molecules. The multiple -OH groups enable various chemical reactions, including esterification and etherification, and contribute to strong interactions with water.

Applications of polyhydroxy compounds are broad. In materials science, polyols serve as chain extenders or crosslinkers in polyurethane foams and resins. In consumer products, they act as humectants and plasticizers. In the food and pharmaceutical industries, sugar alcohols are used as low-calorie sweeteners and stabilizers. Biodiesel production and other industrial processes also yield glycerol as a common polyhydroxy byproduct.

In biology, polyhydroxy compounds are central to metabolism and osmotic balance. Glycerol can be converted to glyceraldehyde-3-phosphate and enters glycolysis. Some organisms accumulate polyols as compatible solutes to endure osmotic stress. Safety considerations include gastrointestinal effects from excessive intake of certain polyols.

Overall, polyhydroxy compounds are defined by their multiple hydroxyl groups, which drive their chemical behavior and wide range of practical applications.