Methyl salicylate
Overview
 
Methyl salicylate is a natural product of many species of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s. Some of the plants which produce it are called wintergreen
Wintergreen
Wintergreen is a group of plants. Wintergreen once commonly referred to plants that continue photosynthesis throughout the winter...

s, hence the common name.
Plants containing methyl salicylate produce this organic ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

 (a combination of an organic acid
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...

 with an alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

) most likely as an anti-herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

 defense. If the plant is infected with herbivorous insects, the release of methyl salicylate may function as an aid in the recruitment of beneficial insects to kill the herbivorous insects.
Discussions
Encyclopedia
Methyl salicylate is a natural product of many species of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s. Some of the plants which produce it are called wintergreen
Wintergreen
Wintergreen is a group of plants. Wintergreen once commonly referred to plants that continue photosynthesis throughout the winter...

s, hence the common name.

Botanical background

Plants containing methyl salicylate produce this organic ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

 (a combination of an organic acid
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...

 with an alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

) most likely as an anti-herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

 defense. If the plant is infected with herbivorous insects, the release of methyl salicylate may function as an aid in the recruitment of beneficial insects to kill the herbivorous insects. Aside from its toxicity, methyl salicylate may also be used by plants as a pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...

 to warn other plants of pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...

s such as tobacco mosaic virus
Tobacco mosaic virus
Tobacco mosaic virus is a positive-sense single stranded RNA virus that infects plants, especially tobacco and other members of the family Solanaceae. The infection causes characteristic patterns on the leaves . TMV was the first virus to be discovered...

. Numerous plants produce methyl salicylate in very small amounts.

Plants producing it in significant amounts (readily detected by scent) include:
  • most species of the family Pyrolaceae
    Pyrolaceae
    Pyrolaceae was a small family of flowering plants under the old Cronquist system of plant classification. It included the four genera Chimaphila, Moneses, Orthilia, and Pyrola, and sometimes also the eight genera formerly usually placed in the family Monotropaceae.Recent genetic research by the...

    , particularly those in the genus Pyrola
    Pyrola
    Pyrola is a genus of evergreen herbaceous plants in the family Ericaceae. Under the old Cronquist system it was placed in its own family Pyrolaceae, but genetic research showed it belonged in the family Ericaceae. The species are commonly known as wintergreen, a name shared with several other...

    ;
  • some species of the genus Gaultheria
    Gaultheria
    Gaultheria is a genus of about 170-180 species of shrubs in the family Ericaceae. The name memorializes Jean François Gauthier of Quebec, a mis-spelt honour bestowed by the Scandinavian Pehr Kalm in 1748. These plants are native to Asia, North and South America, and Australasia...

    in the family Ericaceae
    Ericaceae
    The Ericaceae, commonly known as the heath or heather family, is a group of mostly calcifuge flowering plants. The family is large, with roughly 4000 species spread across 126 genera, making it the 14th most speciose family of flowering plants...

    , including Gaultheria procumbens, the wintergreen or eastern teaberry;
  • some species of the genus Betula
    Birch
    Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...

    in the family Betulaceae
    Betulaceae
    Betulaceae, or the Birch Family, includes six genera of deciduous nut-bearing trees and shrubs, including the birches, alders, hazels, hornbeams and hop-hornbeams, numbering about 130 species...

    , particularly those in the subgenus Betulenta such as B. lenta, the black birch;
  • all species of the genus Spiraea
    Spiraea
    Spiraea , is a genus of about 80-100 species of shrubs in the family Rosaceae, subfamily Spiraeoideae. They are native to the temperate Northern Hemisphere, with the greatest diversity in eastern Asia....

    in the family Rosaceae
    Rosaceae
    Rosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...

    , also called the meadowsweets.

Commercial production

Methyl salicylate can be produced by esterifying salicylic acid
Salicylic acid
Salicylic acid is a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid. 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...

 with methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

. Commercial methyl salicylate is now synthesized, but in the past, it was commonly distilled from the twigs of Betula lenta (sweet birch) and Gaultheria procumbens (eastern teaberry or wintergreen).

Uses

Methyl salicylate is used as a rubefacient
Rubefacient
A rubefacient is a substance for topical application that produces redness of the skin e.g. by causing dilation of the capillaries and an increase in blood circulation. There is limited evidence as to their efficacy ; and as of 2010 the best evidence does not support using gels and creams...

 in deep heating liniment
Liniment
Liniment , from the Latin linere, to anoint, is a medicated topical preparation for application to the skin. Preparations of this type are also called balm...

s (such as Bengay ointment), and in small amounts as a flavoring agent at no more than 0.04%. It is also used to provide fragrance to various products and as an odor-masking agent for some organophosphate
Organophosphate
An organophosphate is the general name for esters of phosphoric acid. Phosphates are probably the most pervasive organophosphorus compounds. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactors that are essential for life...

 pesticides. If applied in too high quantities it can cause stomach and kidney problems.

Methyl salicylate is among the compounds that attract male orchid bees, who apparently gather the chemical to synthesize pheromones; it is commonly used as bait to attract and collect these bees for study.

Methyl salicylate has the ability to clear plant or animal tissue samples of color, and as such is useful for microscopy and immunohistochemistry when excess pigments obscure structures or block light in the tissue being examined. This clearing generally only takes a few minutes, but the tissue must first be dehydrated in alcohol.

Methyl salicylate, though its source plants are not true mints
Mentha
Mentha is a genus of flowering plants in the family Lamiaceae . The species are not clearly distinct and estimates of the number of species varies from 13 to 18. Hybridization between some of the species occurs naturally...

, is used as a mint in some kinds of chewing gum
Chewing gum
Chewing gum is a type of gum traditionally made of chicle, a natural latex product, or synthetic rubber known as polyisobutylene. For economical and quality reasons, many modern chewing gums use rubber instead of chicle...

 and candy, as an alternative to the more common peppermint
Peppermint
Peppermint is a hybrid mint, a cross between the watermint and spearmint . The plant, indigenous to Europe, is now widespread in cultivation throughout all regions of the world...

 and spearmint
Spearmint
Mentha spicata syn. M. cordifolia is a species of mint native to much of Europe and southwest Asia, though its exact natural range is uncertain due to extensive early cultivation. It grows in wet soils...

 oils. It can also be found as a flavoring of root beer
Root beer
Root beer is a carbonated, sweetened beverage, originally made using the root of a sassafras plant as the primary flavor. Root beer, popularized in North America, comes in two forms: alcoholic and soft drink. The historical root beer was analogous to small beer in that the process provided a drink...

. It is also a potentially entertaining source of triboluminescence
Triboluminescence
Triboluminescence is an optical phenomenon in which light is generated when material is pulled apart, ripped, scratched, crushed, or rubbed through the breaking of chemical bonds in the material. The phenomenon is not fully understood, but appears to be caused by the separation and reunification...

; when mixed with sugar and dried, it gains the tendency to build up electrical charge when crushed or rubbed. This effect can be observed by crushing wintergreen Life Savers
Life Savers
Life Savers is an American brand of ring-shaped mints and artificially fruit-flavored hard candy. The candy is known for its distinctive packaging, coming in aluminum foil rolls....

 candy in a dark room.

Methyl salicylate can be used as a transfer agent, to produce a manual copy of an image on a surface.

Methyl salicylate is added in small amounts to glacial acetic acid to lower its freezing point for transport in cold countries.

Methyl salicylate is used as a simulant or surrogate for the research of chemical warfare agent sulfur mustard
Sulfur mustard
The sulfur mustards, or sulphur mustards, commonly known as mustard gas, are a class of related cytotoxic, vesicant chemical warfare agents with the ability to form large blisters on exposed skin. Pure sulfur mustards are colorless, viscous liquids at room temperature...

, due to its similar chemical and physical properties.

Methyl salicylate is one of several antiseptic ingredients in Listerine mouthwash produced by the Johnson & Johnson
Johnson & Johnson
Johnson & Johnson is an American multinational pharmaceutical, medical devices and consumer packaged goods manufacturer founded in 1886. Its common stock is a component of the Dow Jones Industrial Average and the company is listed among the Fortune 500....

 company. It is also used in the "Dencorub Extra Strength" heat cream, which is used to treat joint and muscular pain and is a product of the Dencorub company.

Safety and toxicity

In pure form, methyl salicylate is toxic, especially when taken internally. A single teaspoon (5ml) of methyl salicylate contains 7g of salicylate, which is equivalent to more than twenty-three 300 mg aspirin
Aspirin
Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...

 tablets. The lowest published lethal dose is 101 mg/kg body weight in adult humans, (or 7.07 grams for a 70-kg adult). It has proven fatal to small children in doses as small as 4 ml. A seventeen-year-old cross-country runner at Notre Dame Academy
Notre Dame Academy (New York)
Notre Dame Academy is a private, Roman Catholic high school on Staten Island in New York, New York. It is located within the Roman Catholic Archdiocese of New York.-Background:...

 on Staten Island
Staten Island
Staten Island is a borough of New York City, New York, United States, located in the southwest part of the city. Staten Island is separated from New Jersey by the Arthur Kill and the Kill Van Kull, and from the rest of New York by New York Bay...

, died in April 2007, after her body absorbed methyl salicylate through excessive use of topical muscle-pain relief products.

Most instances of human toxicity due to methyl salicylate are a result of over-application of topical analgesics, especially involving children. Some people have intentionally ingested large amounts of oil of wintergreen. Salicylate, the major metabolite of methyl salicylate, may be quantitated in blood, plasma or serum to confirm a diagnosis of poisoning in hospitalized patients or to assist in an autopsy
Autopsy
An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...

.

External links

Toxicity:
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