Methyl salicylate

Ball-and-stick Stick Space-filling

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19 atoms, 19 bonds.

IUPAC name: methyl 2-hydroxybenzoate
Molar mass: 152.149(21) g/mol
Atoms: 19
SMILES: COC(=O)C1=CC=CC=C1O
InChIKey: OSWPMRLSEDHDFF-UHFFFAOYSA-N
PubChem CID: 4133

Made of

Structural formula of methyl salicylate. Each unlabelled corner is a carbon atom, and the four hydrogens on carbon are not drawn. It shows which atoms are joined to which, not the shape. The model above shows the shape.

Methyl salicylate, methyl 2-hydroxybenzoate by its IUPAC name, has the characteristic smell and taste of wintergreen, as the Hazardous Substances Data Bank (HSDB) describes the liquid. ChEBI, a dictionary of molecules that matter to biology, classes it as the methyl ester of salicylic acid. It is built from carbon, hydrogen and oxygen as C₈H₈O₃, with a molar mass of 152.15 g/mol. Vanillin has exactly that formula and mass but arranges its atoms differently. Its ring carries an aldehyde, a methoxy and a hydroxyl group, where methyl salicylate’s carries an ester and a hydroxyl.

At room temperature the compound is a liquid, colourless, yellowish or reddish in the description of CAMEO Chemicals, a US hazardous-materials database. It is denser than water, so it sinks, and dissolves in it only slightly. Oils, alcohol and other organic solvents take it up readily. The Flavor and Extract Manufacturers Association (FEMA) describes its flavour as almond, caramel, peppermint and sharp.

Structure and bonding

In the model, an ester group and a hydroxyl group sit on neighbouring corners of a six-carbon ring. Seen edge-on, the six-carbon hexagon shrinks to a straight line: the ring is flat. From one corner the ester group reaches out, a carbon double-bonded to one oxygen and single-bonded to a second that carries the methyl group, CH₃. The hydroxyl group, OH, sits on the next ring carbon.

Ball-and-stick draws the ring as single and double bonds taking turns. The ring’s pi electrons, the second half of each double bond, really merge into clouds on both faces of the ring, as in benzene. Measured in the model, the six ring bonds share one length, 1.395 Å.

Around the carbonyl carbon, the one double-bonded to oxygen, the model’s three angles are 124.1°, 124.4° and 111.5°. They add up to 360°, a flat corner. Space-filling swells the atoms into a thin slab with the methyl hydrogens bulging from one end.

Where it turns up

Wintergreen itself, Gaultheria procumbens, is an evergreen shrub of the woods of Canada and the United States, according to HSDB. Its slender stems creep, and its white, bell-shaped flowers give way to red berries called checkerberries. The leaves hold the compound bound to glucose as gaultherin, and soaking them for several hours splits it into methyl salicylate and glucose. Steam distillation then carries the oil out of the leaves, often adulterated with sweet birch bark distilled alongside them.

Toothpaste contains it, and perfumers use it in fern and cypress scents, HSDB records. Products containing it run from car care and pet care to pesticides, according to the Consumer Product Information Database. Insects are drawn to it as well: ChEBI records it as an insect attractant, and wintergreen oil can serve as an attractant in pesticide formulations applied to growing crops.

Why it matters

Most methyl salicylate is made in factories by esterifying salicylic acid with methanol, HSDB reports, and the commercial product is about 99 per cent pure. Whichever way it was made, its label must state its origin: synthetic or distilled from plants. Manufacturers and importers reported a US product volume of 1 million to under 5 million pounds for 2023 to the US Environmental Protection Agency (EPA).

Its uses run well beyond flavouring foods, drinks and medicines. HSDB lists it as an ultraviolet (UV) absorber in sunburn lotions, and Haz-Map, a database of workplace hazards, adds a UV light stabiliser in acrylic resins. The same entry names it as a solvent in insecticides, polishes and inks, an antiseptic in oral hygiene products and a carrier for dyes.

Medicine applies it to the skin. MeSH, the National Library of Medicine’s index of medical subjects, records it in over-the-counter liniments, ointments and lotions for musculoskeletal aches and pains. Haz-Map calls it a topical analgesic, a pain reliever put on the body’s surface, in human and veterinary medicine.

Properties

Properties of methyl salicylate Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 4133.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₈H₈O₃
Molar mass	152.149(21) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	8
Hydrogen atoms	8
Oxygen atoms	3
Bonds	19
Single bonds	15
Double bonds	4
PubChem molecular weight	152.15 g/mol	g/mol	PubChem

Safety

Methyl salicylate is harmful if swallowed, and its liquid preparations are a poisoning danger to children. The EU also classes it as able to cause an allergic skin reaction, suspected of damaging the unborn child and harmful to aquatic life. Swallowed in large amounts, it can affect the central nervous system and the body’s acid–base balance, which may bring delirium, tremors and coma, the International Chemical Safety Cards warn. The PubChem Laboratory Chemical Safety Summary gathers these hazards, with Japan’s classification as Danger for severe skin burns and eye damage.

Questions

Is oil of wintergreen the same as methyl salicylate?

The two are hard to tell apart chemically. According to the Hazardous Substances Data Bank, the US Pharmacopeia puts gaultheria (wintergreen) oil, betula (birch) oil and methyl salicylate under one title, and veterinary practice uses the natural and synthetic grades interchangeably. JECFA, the UN's joint expert committee on food additives, lists the pure compound under names such as synthetic wintergreen oil, synthetic sweet birch oil and synthetic teaberry oil.

Is methyl salicylate an ester or a phenol?

Both. ChEBI classes it as a methyl ester, and CAMEO Chemicals lists it among esters and among phenols, benzene rings that carry a hydroxyl group. In the 3D model the ester is the carbon double-bonded to one oxygen and single-bonded to another that holds the CH₃; the phenol part is the OH on the next ring carbon. Alkali splits the ester into methanol and salicylate, according to the Hazardous Substances Data Bank.

Why is methyl salicylate sold in child-resistant packaging?

US Consumer Product Safety Commission rules list liquid preparations of methyl salicylate among the substances that need special child-resistant packaging. The rule is section 1700.14 of title 16 of the Code of Federal Regulations. The rule exists to protect children from serious injury or illness caused by handling, using or swallowing such products. CAMEO Chemicals, a hazardous-materials database, warns that swallowing a relatively small amount of the compound can cause severe poisoning and death.

Is methyl salicylate the same as aspirin?

No. Aspirin, C₉H₈O₄, is a different molecule, with one more carbon and one more oxygen. ChEBI classes methyl salicylate as the methyl ester of salicylic acid, and PubChem lists salicylic acid as its active moiety, the part of a drug responsible for its action. According to the Hazardous Substances Data Bank, it may be absorbed rapidly through intact skin, and much swallowed ester is hydrolysed, split by water, in the gut.

Made of the same elements

C₈H₈O₃ Vanillin 19 atoms, 19 bonds.
C₉H₈O₄ Aspirin 21 atoms, 21 bonds.
C₇H₆O₃ Salicylic acid 16 atoms, 16 bonds.
C₆H₅COOH Benzoic acid 15 atoms, 15 bonds.
C₆H₈O₆ Ascorbic acid 20 atoms, 20 bonds.
C₆H₅CHO Benzaldehyde 14 atoms, 14 bonds.
C₃H₇COOH Butyric acid 14 atoms, 13 bonds.
CH₃COOC₂H₅ Ethyl acetate 14 atoms, 13 bonds.

All 51 compounds made of carbon, hydrogen and oxygen

C₃H₈O₃ Glycerol 14 atoms, 13 single bonds.
C₄H₈O Butanone 13 atoms, 12 bonds.
C₆H₈O₇ Citric acid 21 atoms, 20 bonds.
C₆H₅OH Phenol 13 atoms, 13 bonds.
C₃H₈O₂ Propylene glycol 13 atoms, 12 single bonds.
C₃H₇OH 1-Propanol 12 atoms, 11 single bonds.
C₃H₈O Isopropyl alcohol 12 atoms, 11 single bonds.
C₃H₆O₃ Lactic acid 12 atoms, 11 bonds.
C₄H₉OH 1-Butanol 15 atoms, 14 single bonds.
C₂H₅OC₂H₅ Diethyl ether 15 atoms, 14 single bonds.
C₄H₆O₅ Malic acid 15 atoms, 14 bonds.
C₂H₅COOH Propionic acid 11 atoms, 10 bonds.
C₃H₆O Acetone 10 atoms, 9 bonds.
C₂H₆O₂ Ethylene glycol 10 atoms, 9 single bonds.
C₆H₁₂O₆ Fructose 24 atoms, 24 single bonds.
C₆H₁₂O₆ Glucose 24 atoms, 24 single bonds.
C₄H₆O₆ Tartaric acid 16 atoms, 15 bonds.
CH₃OCH₃ Dimethyl ether 9 atoms, 8 single bonds.
C₂H₅OH Ethanol 9 atoms, 8 single bonds.
C₂H₄O₃ Glycolic acid 9 atoms, 8 bonds.
CH₃COOH Acetic acid 8 atoms, 7 bonds.
CH₃CHO Acetaldehyde 7 atoms, 6 bonds.
C₂H₄O Ethylene oxide 7 atoms, 7 single bonds.
C₁₄H₁₄O₃ Naproxen 31 atoms, 32 bonds.
H₂CO₃ Carbonic acid 6 atoms, 5 bonds.
CH₃OH Methanol 6 atoms, 5 single bonds.
H₂C₂O₄ Oxalic acid 8 atoms, 7 bonds.
HCOOH Formic acid 5 atoms, 4 bonds.
CH₂O Formaldehyde 4 atoms, 3 bonds.
C₁₅H₁₆O₂ Bisphenol A 33 atoms, 34 bonds.
C₁₃H₁₈O₂ Ibuprofen 33 atoms, 33 bonds.
C₁₀H₂₀O Menthol 31 atoms, 31 single bonds.
C₂₀H₁₄O₄ Phenolphthalein 38 atoms, 41 bonds.
C₁₂H₂₂O₁₁ Lactose 45 atoms, 46 single bonds.
C₁₂H₂₂O₁₁ Sucrose 45 atoms, 46 single bonds.
C₁₈H₂₄O₂ Estradiol 44 atoms, 47 bonds.
C₁₉H₂₈O₂ Testosterone 49 atoms, 52 bonds.
C₁₆H₃₂O₂ Palmitic acid 50 atoms, 49 bonds.
C₂₁H₃₀O₂ Progesterone 53 atoms, 56 bonds.
C₂₁H₃₀O₅ Cortisol 56 atoms, 59 bonds.
C₁₈H₃₄O₂ Oleic acid 54 atoms, 53 bonds.
C₂₇H₄₄O Cholecalciferol 72 atoms, 74 bonds.
C₂₇H₄₆O Cholesterol 74 atoms, 77 bonds.