Hydroxyaldehydes

Hydroxyaldehydes are organic compounds that contain both an aldehyde group (CHO) and one or more hydroxyl (-OH) groups within the same molecule. They are a subset of carbonyl compounds and are encountered in carbohydrates and in various synthetic contexts. The hydroxy group can be located at different positions relative to the aldehyde, giving alpha-, beta-, or other hydroxyaldehydes. Alpha-hydroxyaldehydes, with the hydroxyl on the carbon adjacent to the aldehyde, are among the most common. The simplest example is glycolaldehyde (2-hydroxyethanal). Lactaldehyde (2-hydroxypropanal) is another representative. Glyceraldehyde is a higher-hydroxyl member of this family, commonly described as a dihydroxyaldehyde.

In solution, hydroxyaldehydes can form hydrates and intramolecular hemiacetals; the alpha-hydroxy arrangement facilitates hemiacetal formation. They are reactive in aldol reactions, enabling carbon–carbon bond formation in organic synthesis. Reduction of the aldehyde gives hydroxyalkyl alcohols (polyols); oxidation can yield hydroxy acids or diacids depending on extent.

Occurrence and uses: In biology, simple sugars such as glyceraldehyde are hydroxyaldehydes or closely related; as intermediates in glycolysis and carbohydrate metabolism, or in synthesis of fragrance compounds where hydroxyaldehydes impart floral or fruity notes. They also serve as building blocks in pharmaceuticals, polymers, and agrochemicals.

Production and safety: Hydroxyaldehydes are typically prepared by partial oxidation of polyols or by selective oxidation of sugars, or by functional-group manipulation in carbohydrate chemistry. They may be irritants and should be handled with standard laboratory precautions for aldehydes, including avoidance of inhalation and contact with skin or eyes.