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. Th ...

that contains a

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxyl ...

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 res ...

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 Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substanc ...

, 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. Mi ...

, 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

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. {, class="wikitable" ! Name ! p''K''_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 ...

, , 4.87Handbook of Chemistry and Physics, CRC press, 58th edition page D150-151 (1977) , - , α-Hydroxypropionic acid , , 3.86Dawson, R. M. C. ''et al''., ''Data for Biochemical Research'', Oxford, Clarendon Press, 1959. , - ,

β-Hydroxypropionic acid 3-Hydroxypropionic acid is a carboxylic acid, specifically a beta hydroxy acid. It is an acidic viscous liquid with a pKa of 4.5. It is very soluble in water, soluble in ethanol and diethyl ether. Upon distillation, it dehydrates to form acryli ...

, , 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 wo ...

Carnitine Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. In support of energy metabolism, carnitine transports long-chain fatty acids into mitochondria to be oxidized for energy production, ...

Salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substanc ...

, a β-hydroxy acid

References

ar:حمض هيدروكسي

Acidic properties

See also

References