A beta hydroxy acid or β-hydroxy acid (BHA) is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...
that contains a
carboxylic acid functional group
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the re ...
and
hydroxy functional group separated by ''two'' carbon atoms. They are closely related to
alpha hydroxy acid
α-Hydroxy acids, or alpha hydroxy acids (AHAs), are a class of chemical compounds that consist of a carboxylic acid with a hydroxyl group substituent on the adjacent (alpha) carbon. Prominent examples are glycolic acid, lactic acid, mandelic ac ...
s, in which the two functional groups are separated by ''one'' carbon atom.
In cosmetics, the term ''beta hydroxy acid'' refers specifically to
salicylic acid, which is used in some "anti-aging" creams and
acne
Acne, also known as ''acne vulgaris'', is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and ...
treatments. It is used to combat inflammation.
Upon
dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
, beta-hydroxy acids yield an
alpha-beta unsaturated acid.
Acidic properties
Compared to non-hydroxylated carboxylic acids, this group of acids is stronger, although less strong than the
alpha hydroxy acid
α-Hydroxy acids, or alpha hydroxy acids (AHAs), are a class of chemical compounds that consist of a carboxylic acid with a hydroxyl group substituent on the adjacent (alpha) carbon. Prominent examples are glycolic acid, lactic acid, mandelic ac ...
s. Due to the larger distance, the intramolecular hydrogen bridge is less easily formed compared to the alpha hydroxy acids. The table summarizes some values on the propionic series.
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! Name
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a
, -
,
Propanoic acid
Propionic acid (, from the Greek words πρῶτος : ''prōtos'', meaning "first", and πίων : ''píōn'', meaning "fat"; also known as propanoic acid) is a naturally occurring carboxylic acid with chemical formula CH3CH2CO2H. It is a liqu ...
, , 4.87
[Handbook of Chemistry and Physics, CRC press, 58th edition page D150-151 (1977)]
, -
,
α-Hydroxypropionic acid , , 3.86
[Dawson, R. M. C. ''et al''., ''Data for Biochemical Research'', Oxford, Clarendon Press, 1959.]
, -
,
β-Hydroxypropionic acid , , 4.51
Other beta hydroxy acids include:
*
β-Hydroxybutyric acid
*
β-Hydroxy β-methylbutyric acid
β-Hydroxy β-methylbutyric acid (HMB), otherwise known as its conjugate base, , is a naturally produced substance in humans that is used as a dietary supplement and as an ingredient in certain medical foods that are intended to promote wou ...
*
Carnitine
*
Salicylic acid, a β-hydroxy acid
See also
*
Alpha hydroxy acid
α-Hydroxy acids, or alpha hydroxy acids (AHAs), are a class of chemical compounds that consist of a carboxylic acid with a hydroxyl group substituent on the adjacent (alpha) carbon. Prominent examples are glycolic acid, lactic acid, mandelic ac ...
*
Omega hydroxy acid Omega hydroxy acids (also known as ω-hydroxycarboxylic acids) are a class of naturally occurring straight-chain aliphatic organic acids ''n'' carbon atoms long with a carboxyl group at position 1 (the starting point for the family of carboxylic ac ...
References
ar:حمض هيدروكسي