CID 681

C₈H₁₁NO₂

Dopamine

C 8
H 11
N 1
O 2

Ball-and-stick Stick Space-filling

Drag to rotate; pinch or Ctrl + scroll to zoom. Arrow keys rotate, + − zoom, R resets.

22 atoms, 22 bonds.

IUPAC name: 4-(2-aminoethyl)benzene-1,2-diol
Molar mass: 153.181(21) g/mol
Atoms: 22
SMILES: C1=CC(=C(C=C1CCN)O)O
InChIKey: VYFYYTLLBUKUHU-UHFFFAOYSA-N
PubChem CID: 681

Made of

C H N O

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

Dopamine is one of the brain’s neurotransmitters, the chemical messengers passed between nerve cells, and Medical Subject Headings (MeSH) ties it to the control of movement. It makes up more than half of the catecholamine in the central nervous system, according to the Hazardous Substances Data Bank (HSDB). Catecholamines are the family of messengers that includes dopamine, norepinephrine and epinephrine. Amounts run very high in the basal ganglia, brain areas involved in motivation and habits. The molecule is built from carbon, hydrogen, nitrogen and oxygen as C₈H₁₁NO₂, 153.18 g/mol.

Its IUPAC name, 4-(2-aminoethyl)benzene-1,2-diol, reads almost like a sketch. ChEBI (Chemical Entities of Biological Interest) calls it catechol, a ring with two neighbouring –OH groups, whose position-4 hydrogen has been replaced by a 2-aminoethyl chain. The body makes it from the amino acid tyrosine and converts it onward to norepinephrine and epinephrine, according to MeSH. The free base is highly sensitive to oxygen and discolours quickly in air, according to HSDB.

Structure and bonding

Dopamine has 22 atoms, with a six-carbon ring at one end and both oxygens on adjacent ring carbons, each capped by a hydrogen. Opposite runs a two-carbon chain ending in a nitrogen with two hydrogens. Stick draws the bonds alone. Turned edge-on, the ring, both O–H groups and the first chain carbon lie in one flat plane, while the second carbon and the nitrogen swing out of it. The Space-filling view merges all this into a flat disc with a short tail, and Labels prints C, H, N and O on every atom.

The ring is drawn with alternating single and double bonds, three double, which is one of two equivalent patterns. Yet all six ring bonds in the model measure 1.395 Å. Chem1 treats such a ring as a resonance hybrid, as in benzene. Its π electrons, the second half of each double bond, spread in rings of charge above and below the ring’s plane.

The model also shows the uncharged molecule. Dopamine can take on a proton to form the dopaminium ion, an acid with a pK_a of 8.93 according to HSDB. The pK_a is the negative logarithm of an acid’s dissociation constant.

Where it turns up

Nerve cells in the substantia nigra, an area of the brain, produce dopamine, according to the US National Institute of Neurological Disorders and Stroke (NINDS). Levels are also high in the caudate nucleus and the nucleus accumbens, according to HSDB. ChEBI lists dopamine as a human metabolite, and as a mouse and an Escherichia coli metabolite too.

Plants carry it as well. The LOTUS natural-products database reports it in Magnolia officinalis and Senegalia berlandieri, and PubChem links it to the flowering tops of Cytisus scoparius.

In hospitals it appears as dopamine hydrochloride, the salt, including preparations made up in dextrose solution. The US Food and Drug Administration’s list of approved drug products includes dopamine hydrochloride among currently marketed prescription drugs, according to HSDB. The World Health Organization classes it as a cardiac stimulant, code C01CA04, and includes it on its Model Lists of Essential Medicines.

Why it matters

In Parkinson’s disease the supply fails. NINDS traces most of its symptoms to nerve cells in the substantia nigra weakening and dying, which leaves the brain short of the dopamine that smooths movement. A shifted balance between dopamine and acetylcholine can then produce tremor. NINDS also points to damage in cells that make norepinephrine as a likely cause of some symptoms unrelated to movement. Inhibitors of monoamine oxidase B (MAO-B), an enzyme that breaks dopamine down, raise its level in the brain.

In the bloodstream dopamine acts on the heart and vessels through receptors, proteins a messenger binds to. Through beta-1 adrenergic receptors in heart muscle it raises heart rate and the force of each beat, according to the National Cancer Institute Thesaurus. It also releases norepinephrine from nerve endings, a second route to that effect, according to HSDB. Its action on vessels depends on the receptor: alpha-1 receptors narrow them, while D1 receptors widen them through cyclic AMP, a messenger inside the cell. Its medical uses, per HSDB, are severe congestive heart failure and cardiogenic and septic shock.

Properties

Properties of dopamine Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 681.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₈H₁₁NO₂
Molar mass	153.181(21) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	8
Hydrogen atoms	11
Nitrogen atoms	1
Oxygen atoms	2
Bonds	22
Single bonds	19
Double bonds	3
PubChem molecular weight	153.18 g/mol	g/mol	PubChem

Safety

Pure dopamine carries the signal word Warning under the Globally Harmonized System (GHS) classification notified to the European Chemicals Agency. Its hazard statements are harmful if swallowed, suspected of damaging fertility or an unborn child, and very toxic to aquatic life, with effects that last. For people handling the hydrochloride powder, HSDB notes possible irritation of the eyes, skin and airways, and the salt emits toxic fumes in a fire. The PubChem Laboratory Chemical Safety Summary is the full hazard sheet.

Questions

What does the dopamine molecule look like?

It is a benzene ring with two O–H groups on neighbouring carbons and a CH₂CH₂NH₂ chain, C₈H₁₁NO₂, 153.18 g/mol. As a solid it forms stout prisms, and the hydrochloride used in medicine is a white crystalline powder, according to HSDB. It is freely soluble in water and methanol but practically insoluble in ether, chloroform, benzene and toluene.

Is dopamine the pleasure chemical?

Not in the simple sense. The National Institute on Drug Abuse (NIDA) says researchers once thought drug-driven surges of dopamine caused euphoria directly. Its current account links dopamine to reinforcement, the urge to repeat something rewarding, while the pleasure itself probably involves endorphins and other neurotransmitters. Large dopamine surges from drugs train the brain to seek the drug ahead of healthier goals, on NIDA's account.

Why can't people with Parkinson's disease just take dopamine?

Dopamine given into the blood does not pass easily into the brain. The blood–brain barrier, a layer of cells lining the brain's blood vessels, tightly controls what gets through, according to the US National Institute of Neurological Disorders and Stroke (NINDS). Levodopa does reach the brain, where it is converted into dopamine. Carbidopa, often paired with it, blocks levodopa's breakdown elsewhere in the body, so more of it gets into the brain.

How does the body make and break down dopamine?

Cells build it from the amino acid tyrosine, and it is in turn the starting point for norepinephrine and epinephrine, according to MeSH. Its main route of removal has two steps, according to HSDB. An enzyme called catechol-O-methyltransferase adds a methyl group to one oxygen, giving 3-methoxytyramine. That product is then either joined to a sulfate group or stripped of its amino group (deaminated) by monoamine oxidase (MAO) to homovanillic acid.

Made of the same elements

C₉H₁₁NO₂ Phenylalanine 23 atoms, 23 bonds.
C₈H₉NO₂ Acetaminophen 20 atoms, 20 bonds.
C₉H₁₁NO₃ Tyrosine 24 atoms, 24 bonds.
C₈H₁₀N₄O₂ Caffeine 24 atoms, 25 bonds.
C₉H₁₃NO₃ Epinephrine 26 atoms, 26 bonds.
C₆H₁₃NO₂ Isoleucine 22 atoms, 21 bonds.
C₆H₁₃NO₂ Leucine 22 atoms, 21 bonds.
C₁₀H₁₂N₂O Serotonin 25 atoms, 26 bonds.

All 25 compounds made of carbon, hydrogen, nitrogen and oxygen

C₁₁H₁₂N₂O₂ Tryptophan 27 atoms, 28 bonds.
C₅H₉NO₄ Glutamic acid 19 atoms, 18 bonds.
C₃H₇NO₂ Alanine 13 atoms, 12 bonds.
C₅H₆N₂O₂ Thymine 15 atoms, 15 bonds.
C₁₂H₁₇NO DEET 31 atoms, 31 bonds.
C₁₃H₁₆N₂O₂ Melatonin 33 atoms, 34 bonds.
C₂H₅NO₂ Glycine 10 atoms, 9 bonds.
C₄H₄N₂O₂ Uracil 12 atoms, 12 bonds.
C₄H₅N₃O Cytosine 13 atoms, 13 bonds.
C₅H₅N₅O Guanine 16 atoms, 17 bonds.
C₅H₄N₄O₃ Uric acid 16 atoms, 17 bonds.
C₁₃H₂₁NO₃ Albuterol 38 atoms, 38 bonds.
CO(NH₂)₂ Urea 8 atoms, 7 bonds.
C₁₄H₁₈N₂O₅ Aspartame 39 atoms, 39 bonds.
C₁₄H₂₂N₂O Lidocaine 39 atoms, 39 bonds.
C₁₇H₂₁NO Diphenhydramine 40 atoms, 41 bonds.
C₂₀H₂₄N₂O₂ Quinine 48 atoms, 51 bonds.