Adrenaline (Epinephrine) (C₉H₁₃NO₃) — Properties, Uses & Safety

Overview

Adrenaline (C9H13NO3), also known as epinephrine, is the fight-or-flight hormone that prepares the body for emergency action. With a molar mass of 183.20 g/mol, adrenaline is a catecholamine — a class of compounds featuring a catechol ring (a benzene ring with two adjacent hydroxyl groups) attached to an amine side chain. It is produced by the adrenal medulla (the inner part of the adrenal glands sitting atop the kidneys) and by certain neurons in the central nervous system. When you face a sudden threat or stressful situation, the sympathetic nervous system triggers a rapid release of adrenaline into the bloodstream. Within seconds, adrenaline binds to adrenergic receptors throughout the body, producing dramatic physiological changes: heart rate and blood pressure increase, airways dilate for improved breathing, blood flow is redirected to muscles, pupils dilate for better vision, blood sugar rises as the liver converts glycogen to glucose, and non-essential functions like digestion are suppressed. These responses evolved to help organisms survive dangerous situations by enhancing physical performance. Medically, synthetic epinephrine is a life-saving drug. It is the first-line treatment for anaphylaxis (severe allergic reactions), administered via auto-injectors like the EpiPen. It is also used in cardiac arrest (to restore heart rhythm), severe asthma attacks (as a bronchodilator), and combined with local anesthetics (to constrict blood vessels and prolong anesthetic effect). Adrenaline was one of the first hormones to be isolated (by Jokichi Takamine in 1901) and the first to be synthesized in a laboratory. Structurally, adrenaline contains a chiral center, and only the R-(-)-enantiomer is biologically active — a classic example of enantioselective biological activity. It is biosynthesized from the amino acid tyrosine through a pathway involving dopamine and norepinephrine as intermediates. GHS classifications include acute toxicity (skull and crossbones) for the pure compound. For chemistry students, adrenaline connects organic chemistry concepts including catechol and phenol chemistry, chirality and biological enantioselectivity, amine functional groups, biosynthetic pathways, and receptor-ligand interactions. Its dramatic physiological effects make it one of the most exciting molecules to study at the intersection of chemistry and human biology.

IUPAC Name

(R)-4-(1-hydroxy-2-(methylamino)ethyl)benzene-1,2-diol

CAS Number

51-43-4

PubChem CID

5816

Molecular Formula

C₉H₁₃NO₃

Molar Mass

183.204 g/mol

State at STP

solid

Appearance

White to brownish microcrystalline powder