Definition

1. Noun:
   • A type of organic acid: A hydroxy acid is any acid that contains one or more hydroxyl (-OH) groups in its molecular structure, in addition to the hydroxyl group that is part of the characteristic carboxylic acid (-COOH) group itself.

Usage and Examples

• Noun:
  • Alpha hydroxy acids, like glycolic acid, are common ingredients in skincare products for exfoliation.
  • Citric acid, found in citrus fruits, is a well-known hydroxy acid.
  • The chemist synthesized a new hydroxy acid for the experiment.

Advanced Usage and Notes

• Hydroxy acids are classified into subgroups based on the position of the hydroxyl group relative to the carboxylic acid group. The two primary categories are:
  • Alpha hydroxy acids (AHAs): The hydroxyl group is on the carbon atom adjacent (alpha) to the carboxyl group. Examples include glycolic acid and lactic acid.
  • Beta hydroxy acids (BHAs): The hydroxyl group is on the second carbon atom (beta) from the carboxyl group. Salicylic acid is a common example.
• In biochemistry, many hydroxy acids are important intermediates in metabolic cycles, such as the citric acid cycle.

Variants and Related Words

• Alpha hydroxy acid (AHA) (n): A subclass of hydroxy acids used extensively in cosmetics and dermatology.
• Beta hydroxy acid (BHA) (n): A subclass of hydroxy acids, with salicylic acid being the most prominent member, often used for its ability to penetrate oily skin.
• Carboxylic acid (n): The broader class of organic acids containing a carboxyl (-COOH) group, to which hydroxy acids belong.
• Hydroxyl group (n): The functional group consisting of an oxygen atom bonded to a hydrogen atom (-OH).

Synonyms and Related Terms

• Hydroxylated acid: A less common term with the same meaning.
• Polyhydroxy acid: A hydroxy acid containing multiple hydroxyl groups.

Common Phrases and Contexts

• Hydroxy acid peel: A cosmetic procedure using a concentrated solution of hydroxy acids to improve skin texture.
• Fruit acid: A common marketing term for alpha hydroxy acids derived from fruit sugars, such as glycolic acid (from sugar cane) or malic acid (from apples).

Noun

1. any acid that has hydroxyl groups in addition to the hydroxyl group in the acid itself