العربية
中国
Français
Deutsch
Ελληνική
हिन्दी
Italiano
日本語
Português
Русский
EspañolSALICYLIC ACID
(Redirected from Salicylate)
'Salicylic acid' (from the Latin word for the willow tree, ''Salix'' from whose bark it can be obtained) is a beta hydroxy acid (BHA) with the formula C6H4(OH)CO2H, where the OH group is adjacent to the carboxyl group. 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. It is probably best known as a compound that is chemically similar but not identical to the active component of aspirin.
Salicylic acid (SA) is a phytohormone; and a phenol, ubiquitous in plants generating a significant impact on plant growth and development, photosynthesis, transpiration, ion uptake and transport and also induces specific changes in leaf anatomy and chloroplast structure. SA is recognized as an endogenous signal, mediating in plant defense, against pathogens[1] It plays a role in the resistance of pathogens by inducing the production of 'pathogenesis-related proteins'. It is involved in the systemic acquired resistance [SAR] in which a pathogenic attack on older leaves causes the development of resistance in younger leaves, though whether SA is the transmitted signal is debatable. SA is the calorigenic substance that causes thermogenesis in ''Arum'' flowers. [2]
Salicylic acid is biosynthesized from the amino acid phenylalanine.
Sodium salicylate is commercially prepared by treating sodium phenoxide with a high pressure of carbon dioxide at high temperature via the Kolbe-Schmitt reaction. Acidification of the product solution gives salicylic acid:
:
It can be prepared by the hydrolysis of Aspirin (acetylsalicylic acid) with a strong acid or base (followed by acidification).[3]
Salicylic acid can also be produced by refluxing oil of wintergreen. A crude process is relatively simple, and involves first heating the oil of wintergreen under reflux with a 2M solution of NaOH and antibumping granules. Once the mixture has refluxed for 30 minutes, the mixture is cooled, and concentrated HCl added until the solution is acidic. The solution then undergoes vacuum filtration to separate to solid from the liquid. The crystals are collected and dissolved in a minimum amount of ethanol. It is the hydorxide group from the sodium hyrdoxide that removes a methyl group from the oil of wintergreen, and H+ ion that is attracted to the negatively charged oxygen atom. (Student friendly adaptation from ''Chemical Storylines'', Salters, 2nd publication 2000)
Also known as 2-hydroxybenzoic acid, one of several beta hydroxy acids (compare to AHA), salicylic acid is a key additive in many skin-care products for the treatment of acne, psoriasis, calluses, corns, keratosis pilaris, and warts. It works by causing the cells of the epidermis to slough off more readily, preventing pores from clogging up, and allowing room for new cell growth. Because of its effect on skin cells, salicylic acid is used in several shampoos used to treat dandruff. Salicylic acid is also used as an active ingredient in gels which remove verrucas (plantar warts). Use of concentrated solutions of salicylic acid may cause hyperpigmentation on unpretreated skin for those with darker skin types (Fitzpatrick phototypes IV, V, VI), as well as with the lack of use of a broad spectrum sunblock.[4][5]
The medicinal properties of salicylate, mainly for fever relief, have been known since ancient times, and was used as an inflammatory drug.[6]
Aspirin (acetylsalicylic acid or ASA) can be prepared by the esterification of the phenolic hydroxyl group of salicylic acid.
Subsalicylate in combination with bismuth form the popular stomach relief aid known commonly as Pepto-Bismol. When combined, the two key ingredients help control diarrhea, nausea, heartburn, and gas. It is also a very mild antibiotic.
★ Although toxic in large quantities, salicylic acid is used as a food preservative and antiseptic in toothpaste. For some people with salicylate sensitivity even these small doses can be harmful.
★ Sodium salicylate is a useful phosphor in the vacuum ultraviolet with nearly flat quantum efficiency for wavelengths between 10 to 100 nm.[7] 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.
Salicylic acid has an ototoxic effect, meaning it can induce transient hearing loss, in zinc-deficient individuals.
This finding is based on clinical studies with rats. An injection of salicylic acid induced hearing loss in zinc-deficient rats, while a simultaneous injection of zinc reversed the hearing loss. An injection of magnesium in the zinc-deficient rats did not reverse the salicylic acid-induced hearing loss.
Salicylic acid is toxic in large amounts. Pregnant women are advised not to use products containing salicylic acid due to the danger of Reye's syndrome.
1. Salicylic acid - A Plant Hormone, S. Hayat, A. Ahmad, , , Springer, 2007,
2. Plant Hormones: Biosynthesis, Signal Transduction, Action!, , Peter J., Davies, Springer, ,
3. Hydrolysis of ASA to SA
4. The Safety and Efficacy of Salicylic Acid Chemical Peels in Darker Racial-ethnic Groups, Grimes P.E., , , Dermatologic Surgery, 1999
5. Chemical peeling in ethnic/dark skin, Roberts W. E., , , Dermatologic Therapy, 2004
6. Brief History of Antipyretic Therapy, Philip A. Mackowiak, , , Clinical Infectious Diseases,, 2000
7. JAR Samson ''Techniques of Vacuum Ultraviolet Spectroscopy''
| 'Salicylic acid' | |
|---|---|
 Chemical structure of salicylic acid  Space-filling model of salicylic acid  Salicylic acid crystals on a beaker | |
| Chemical name | 2-Hydroxybenzoic acid |
| Chemical formula | C7H6O3 |
| Molecular mass | 138.123 g/mol |
| Melting point | 159 °C |
| Boiling point | 211 °C (2666 Pa) |
| Density | 1.44 g/cm³ (at 20 °C) |
| pKa | 2.97 |
| CAS number | [69-72-7] |
| SMILES | OC(=O)c1ccccc1O |
| Related compounds | Methyl salicylate, Benzoic acid, Phenol, Aspirin, 4-Hydroxybenzoic acid, Magnesium salicylate, Bismuth subsalicylate (Pepto Bismol), Sulfosalicylic acid |
'Salicylic acid' (from the Latin word for the willow tree, ''Salix'' from whose bark it can be obtained) is a beta hydroxy acid (BHA) with the formula C6H4(OH)CO2H, where the OH group is adjacent to the carboxyl group. 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. It is probably best known as a compound that is chemically similar but not identical to the active component of aspirin.
| Contents |
| Plant Hormone |
| Production |
| Medicinal and cosmetic uses |
| Other uses |
| Safety |
| Footnotes |
Plant Hormone
Salicylic acid (SA) is a phytohormone; and a phenol, ubiquitous in plants generating a significant impact on plant growth and development, photosynthesis, transpiration, ion uptake and transport and also induces specific changes in leaf anatomy and chloroplast structure. SA is recognized as an endogenous signal, mediating in plant defense, against pathogens[1] It plays a role in the resistance of pathogens by inducing the production of 'pathogenesis-related proteins'. It is involved in the systemic acquired resistance [SAR] in which a pathogenic attack on older leaves causes the development of resistance in younger leaves, though whether SA is the transmitted signal is debatable. SA is the calorigenic substance that causes thermogenesis in ''Arum'' flowers. [2]
Production
Salicylic acid is biosynthesized from the amino acid phenylalanine.
Sodium salicylate is commercially prepared by treating sodium phenoxide with a high pressure of carbon dioxide at high temperature via the Kolbe-Schmitt reaction. Acidification of the product solution gives salicylic acid:
:
It can be prepared by the hydrolysis of Aspirin (acetylsalicylic acid) with a strong acid or base (followed by acidification).[3]
Salicylic acid can also be produced by refluxing oil of wintergreen. A crude process is relatively simple, and involves first heating the oil of wintergreen under reflux with a 2M solution of NaOH and antibumping granules. Once the mixture has refluxed for 30 minutes, the mixture is cooled, and concentrated HCl added until the solution is acidic. The solution then undergoes vacuum filtration to separate to solid from the liquid. The crystals are collected and dissolved in a minimum amount of ethanol. It is the hydorxide group from the sodium hyrdoxide that removes a methyl group from the oil of wintergreen, and H+ ion that is attracted to the negatively charged oxygen atom. (Student friendly adaptation from ''Chemical Storylines'', Salters, 2nd publication 2000)
Medicinal and cosmetic uses
Also known as 2-hydroxybenzoic acid, one of several beta hydroxy acids (compare to AHA), salicylic acid is a key additive in many skin-care products for the treatment of acne, psoriasis, calluses, corns, keratosis pilaris, and warts. It works by causing the cells of the epidermis to slough off more readily, preventing pores from clogging up, and allowing room for new cell growth. Because of its effect on skin cells, salicylic acid is used in several shampoos used to treat dandruff. Salicylic acid is also used as an active ingredient in gels which remove verrucas (plantar warts). Use of concentrated solutions of salicylic acid may cause hyperpigmentation on unpretreated skin for those with darker skin types (Fitzpatrick phototypes IV, V, VI), as well as with the lack of use of a broad spectrum sunblock.[4][5]
The medicinal properties of salicylate, mainly for fever relief, have been known since ancient times, and was used as an inflammatory drug.[6]
Aspirin (acetylsalicylic acid or ASA) can be prepared by the esterification of the phenolic hydroxyl group of salicylic acid.
Subsalicylate in combination with bismuth form the popular stomach relief aid known commonly as Pepto-Bismol. When combined, the two key ingredients help control diarrhea, nausea, heartburn, and gas. It is also a very mild antibiotic.
Other uses
★ Although toxic in large quantities, salicylic acid is used as a food preservative and antiseptic in toothpaste. For some people with salicylate sensitivity even these small doses can be harmful.
★ Sodium salicylate is a useful phosphor in the vacuum ultraviolet with nearly flat quantum efficiency for wavelengths between 10 to 100 nm.[7] 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.
Safety
Salicylic acid has an ototoxic effect, meaning it can induce transient hearing loss, in zinc-deficient individuals.
This finding is based on clinical studies with rats. An injection of salicylic acid induced hearing loss in zinc-deficient rats, while a simultaneous injection of zinc reversed the hearing loss. An injection of magnesium in the zinc-deficient rats did not reverse the salicylic acid-induced hearing loss.
Salicylic acid is toxic in large amounts. Pregnant women are advised not to use products containing salicylic acid due to the danger of Reye's syndrome.
Footnotes
1. Salicylic acid - A Plant Hormone, S. Hayat, A. Ahmad, , , Springer, 2007,
2. Plant Hormones: Biosynthesis, Signal Transduction, Action!, , Peter J., Davies, Springer, ,
3. Hydrolysis of ASA to SA
4. The Safety and Efficacy of Salicylic Acid Chemical Peels in Darker Racial-ethnic Groups, Grimes P.E., , , Dermatologic Surgery, 1999
5. Chemical peeling in ethnic/dark skin, Roberts W. E., , , Dermatologic Therapy, 2004
6. Brief History of Antipyretic Therapy, Philip A. Mackowiak, , , Clinical Infectious Diseases,, 2000
7. JAR Samson ''Techniques of Vacuum Ultraviolet Spectroscopy''
This article provided by Wikipedia. To edit the contents of this article, click here for original source.
psst.. try this: add to faves
