Salicylic acid

Salicylic acid
Skeletal formula of salicylic acid
Ball-and-stick model of salicylic acid
Salicylic acid
Names
Preferred IUPAC name
2-Hydroxybenzoic acid[1]
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard100.000.648
EC Number200-712-3
KEGG
RTECS numberVO0525000
UNII
Properties
C7H6O3
Molar mass138.12 g·mol−1
AppearanceColorless to white crystals
OdorOdorless
Density1.443 g/cm3 (20 °C)[2]
Melting point 158.6 °C (317.5 °F; 431.8 K)
Boiling point 200 °C (392 °F; 473 K) decomposes[3]
211 °C (412 °F; 484 K)
at 20 mmHg[2]
Sublimes at 76 °C[4]
  • 1.24 g/L (0 °C)
  • 2.48 g/L (25 °C)
  • 4.14 g/L (40 °C)
  • 17.41 g/L (75 °C)[3]
  • 77.79 g/L (100 °C)[5]
SolubilitySoluble in ether, CCl4, benzene, propanol, acetone, ethanol, oil of turpentine, toluene
Solubility in benzene
  • 0.46 g/100 g (11.7 °C)
  • 0.775 g/100 g (25 °C)
  • 0.991 g/100 g (30.5 °C)
  • 2.38 g/100 g (49.4 °C)
  • 4.4 g/100 g (64.2 °C)[3][5]
Solubility in chloroform
  • 2.22 g/100 mL (25 °C)[5]
  • 2.31 g/100 mL (30.5 °C)[3]
Solubility in methanol
  • 40.67 g/100 g (−3 °C)
  • 62.48 g/100 g (21 °C)[3]
Solubility in olive oil2.43 g/100 g (23 °C)[3]
Solubility in acetone39.6 g/100 g (23 °C)[3]
log P2.26
Vapor pressure10.93 mPa[4]
Acidity (pKa)
  • 1 = 2.97 (25 °C)[6]
  • 2 = 13.82 (20 °C)[3]
UV-vismax)210 nm, 234 nm, 303 nm (4 mg % in ethanol)[4]
−72.23·10−6 cm3/mol
1.565 (20 °C)[2]
Thermochemistry
−589.9 kJ/mol
3.025 MJ/mol[7]
Pharmacology
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Hazards
Safety data sheetMSDS
GHS pictogramsThe corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[8]
GHS signal wordDanger
H302, H318[8]
P280, P305+351+338[8]
Eye hazardSevere irritation
Skin hazardMild irritation
NFPA 704
Flash point 157 °C (315 °F; 430 K)
closed cup[4]
540 °C (1,004 °F; 813 K)[4]
Lethal dose or concentration (LD, LC):
480 mg/kg (mice, oral)
Related compounds
Related compounds
Methyl salicylate,
Benzoic acid,
Phenol, Aspirin,
4-Hydroxybenzoic acid,
Magnesium salicylate,
Choline salicylate,
Bismuth subsalicylate,
Sulfosalicylic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Salicylic acid (from Latin salix, willow tree) is a lipophilic monohydroxybenzoic acid, a type of phenolic acid, and a beta hydroxy acid (BHA). It has the formula C7H6O3. This colorless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin. In addition to serving as an important active metabolite of aspirin (acetylsalicylic acid), which acts in part as a prodrug to salicylic acid, it is probably best known for its use as a key ingredient in topical anti-acne products. The salts and esters of salicylic acid are known as salicylates.

It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.[9]

Uses

Medicine

Cotton pads soaked in salicylic acid can be used to chemically exfoliate skin

Salicylic acid as a medication is used most commonly to help remove the outer layer of the skin.[10] As such, it is used to treat warts, psoriasis, acne, ringworm, dandruff, and ichthyosis.[10][11]

As with other hydroxy acids, salicylic acid is a key ingredient in many skincare products for the treatment of seborrhoeic dermatitis, acne, psoriasis, calluses, corns, keratosis pilaris, acanthosis nigricans, ichthyosis and warts.[12]

Manufacturing

Salicylic acid is used in the production of other pharmaceuticals, including 4-aminosalicylic acid, sandulpiride, and landetimide (via Salethamide).

Salicylic acid was one of the original starting materials for making acetylsalicylic acid (aspirin) in 1897.[13]

Bismuth subsalicylate, a salt of bismuth and salicylic acid, is the active ingredient in stomach relief aids such as Pepto-Bismol, is the main ingredient of Kaopectate and "displays anti-inflammatory action (due to salicylic acid) and also acts as an antacid and mild antibiotic".[14]

Other derivatives include methyl salicylate used as a liniment to soothe joint and muscle pain and choline salicylate used topically to relieve the pain of mouth ulcers.

Chemistry

Salicylic acid has the formula C6H4(OH)COOH, where the OH group is ortho to the carboxyl group. It is also known as 2-hydroxybenzoic acid. It is poorly soluble in water (2 g/L at 20 °C).[15] Aspirin (acetylsalicylic acid or ASA) can be prepared by the esterification of the phenolic hydroxyl group of salicylic acid with the acetyl group from acetic anhydride or acetyl chloride. Salicylic acid can also be prepared using the Kolbe-Schmitt reaction.

Other uses

Salicylic acid is used as a food preservative, a bactericidal and an antiseptic.[16]

Sodium salicylate is a useful phosphor in the vacuum ultraviolet spectral range, with nearly flat quantum efficiency for wavelengths between 10 and 100 nm.[17] It fluoresces in the blue at 420 nm. It is easily prepared on a clean surface by spraying a saturated solution of the salt in methanol followed by evaporation.

Other Languages
Deutsch: Salicylsäure
Esperanto: Salikata acido
한국어: 살리실산
հայերեն: Սալիցիլաթթու
Bahasa Indonesia: Asam salisilat
íslenska: Salisýlsýra
latviešu: Salicilskābe
magyar: Szalicilsav
Bahasa Melayu: Asid salisilik
Nederlands: Salicylzuur
日本語: サリチル酸
português: Ácido salicílico
română: Acid salicilic
Simple English: Salicylic acid
slovenščina: Salicilna kislina
српски / srpski: Salicilna kiselina
srpskohrvatski / српскохрватски: Salicilna kiselina
svenska: Salicylsyra
Türkçe: Salisilik asit
Tiếng Việt: Axit salicylic
粵語: 水楊酸
中文: 水楊酸