Nicotine

C 10
H 14
N 2

Ball-and-stick Stick Space-filling

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26 atoms, 27 bonds.

IUPAC name: 3-[(2S)-1-methylpyrrolidin-2-yl]pyridine
Molar mass: 162.236(25) g/mol
Atoms: 26
SMILES: CN1CCCC1C2=CN=CC=C2
InChIKey: SNICXCGAKADSCV-JTQLQIEISA-N
PubChem CID: 89594

Made of

C H N

Structural formula of nicotine. Each unlabelled corner is a carbon atom, and the 11 hydrogens on carbon are not drawn. Wedges come toward you, hashes go back. It shows which atoms are joined to which, not the shape. The model above shows the shape.

The tobacco plant, Nicotiana tabacum, is the species the ChEBI database records natural nicotine as isolated from. NCI Thesaurus, the US National Cancer Institute’s vocabulary, classes it as a plant alkaloid of tobacco, a nitrogen-bearing compound made by the plant. It is built from carbon, hydrogen and nitrogen, with a molar mass of 162.24 g/mol. Its IUPAC name is 3-[(2S)-1-methylpyrrolidin-2-yl]pyridine.

The (2S) in that name marks a chiral centre, a carbon whose four different neighbours can be arranged in two mirror-image ways. ChEBI identifies (S)-nicotine as the form that occurs in nature and the more active of the pair. Pure nicotine is an oily liquid at room temperature, melting at −79 °C and boiling at 247 °C on the Hazardous Substances Data Bank (HSDB) figures. NIOSH, the US federal institute for workplace safety and health, describes it pulling moisture from the air and slowly turning brown in air or light.

Structure and bonding

In the viewer, 26 atoms form two rings joined by one carbon–carbon single bond. The six-membered pyridine ring holds five carbons and a nitrogen; the five-membered pyrrolidine ring holds four carbons and a nitrogen carrying a methyl group. Seen edge-on, the pyridine ring is flat, while the smaller ring is puckered and stands steeply across it. In the model, the pyrrolidine nitrogen’s bonds meet at 106° to 113°, forming a pyramid.

The model draws the pyridine ring as one fixed pattern, two C=C and one C=N alternating with single bonds. Its singles and doubles come out almost equal, 1.38 to 1.39 Å between carbons and 1.352 Å for both carbon–nitrogen bonds. Chem1 calls such alternation a conjugated system, its π bonds (each double bond’s second bond) delocalised along the run. The model shows the neutral base; ChEBI records it as the conjugate base of the nicotinium ion, nicotine plus a hydrogen ion.

Stick reduces the atoms to bond lines, tracing the single link between the rings. Space-filling swells each atom to full size in one lumpy outline. In Chem1’s account of biological signalling, a small molecule docks at a receptor site on a far larger one, often a protein.

Where it turns up

Every tobacco product contains nicotine, according to the US Food and Drug Administration (FDA). That covers cigarettes, cigars, hookah tobacco, most e-cigarettes, and smokeless forms such as snus, snuff, dip or chewing tobacco. Vaping devices, which the National Institute on Drug Abuse (NIDA) notes can look like pens or USB memory sticks, turn flavourings and chemicals into a mist mixed with synthetic nicotine. Outside tobacco, the LOTUS natural-products database reports (−)-nicotine in Camellia sinensis and Senegalia berlandieri.

Commercial nicotine is extracted from waste tobacco of Nicotiana tabacum or N. rustica, on HSDB’s account. By 1985 it was no longer produced in the USA, and limited supplies came from India (HSDB). It reaches pharmacies too, in the patches, gum and lozenges the FDA lists for quitting smoking. HSDB lists it on sale as salts too, among them the sulfate and bitartrate. The Environmental Protection Agency (EPA) lists nicotine, salts included, as an acute hazardous waste, according to the FDA.

Why it matters

Nicotine is the prototype agonist, a molecule that switches a receptor on, at the nicotinic cholinergic receptors, in the description of MeSH, the US medical subject vocabulary. It excites the neurons carrying them strongly at first and in the end blocks their signalling. NCI Thesaurus places these receptors in nerve junctions outside the brain, where nerves meet muscle, in the adrenal glands and in the brain.

Its effect on the heart runs along two routes. NIDA describes nicotine reaching the adrenal glands, which release adrenaline and raise blood pressure, breathing and heart rate. According to NCI Thesaurus, its effects may also run through the release of several brain chemicals, among them acetylcholine, dopamine and serotonin. Narrowed blood vessels and a quicker pulse can follow.

HSDB describes nicotine passing readily into the body through the airways, the lining of the mouth and the skin. The liver breaks it down along two routes, mainly to cotinine and also to nicotine-1’-N-oxide, on HSDB’s account. As a medicine it helps people stop smoking, and LiverTox has not linked it with liver damage.

Properties

Properties of nicotine Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 89594.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₁₀H₁₄N₂
Molar mass	162.236(25) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	10
Hydrogen atoms	14
Nitrogen atoms	2
Bonds	27
Single bonds	24
Double bonds	3
PubChem molecular weight	162.23 g/mol	g/mol	PubChem

Safety

Pure nicotine is acutely toxic whether swallowed, absorbed through the skin or breathed in. The EU’s harmonised classification rates it fatal by each of those routes, and toxic to aquatic life over the long term. NIOSH notes that it acts on the nervous system and the heart. The PubChem Laboratory Chemical Safety Summary and the NIOSH Pocket Guide card give the full workplace guidance.

Questions

What does a nicotine molecule look like?

It is two rings tied together by one carbon–carbon bond, 26 atoms in all with the formula C₁₀H₁₄N₂. One ring has six members, five carbons and a nitrogen; the other has five, four carbons and a nitrogen bearing a methyl group. The carbon where the rings meet is a chiral centre, and ChEBI identifies the S arrangement as the one found in nature.

Why is nicotine so addictive?

Nicotine alters how the brain works and so produces cravings, according to the FDA. Cigarettes are designed to carry it to the brain within seconds, and that speed makes dependence easier to fall into and harder to escape. According to NIDA, a body used to nicotine can feel really unwell once it stops. The FDA adds that young people, whose brains are still developing, are more likely than adults to become addicted.

Is nicotine the harmful part of smoking?

Nicotine keeps people smoking, but the serious health effects of tobacco come from the mixture of other toxic chemicals in it, according to the FDA and NIDA. Nicotine replacement products rest on that split: they supply nicotine without the smoke. The pure compound is still dangerous in its own right, since the EU classifies it as fatal by swallowing, skin contact or breathing.

Was nicotine used as an insecticide?

Yes. Haz-Map records it as popular for killing insects in the 1920s and 1930s, a period that also saw workers poisoned by it. HSDB describes it as a contact insecticide that does not spread through the plant and as a fumigant for glasshouses. The World Health Organization places technical-grade nicotine in its Class IB, highly hazardous pesticides.

Made of the same elements

C₅H₉N₃ Histamine 17 atoms, 17 bonds.
C₄H₁₁N₅ Metformin 20 atoms, 19 bonds.
(CH₃)₃N Trimethylamine 13 atoms, 12 single bonds.
C₅H₅N₅ Adenine 15 atoms, 16 bonds.
C₃H₆N₆ Melamine 15 atoms, 15 bonds.