Ibuprofen (C₁₃H₁₈O₂) — Properties, Uses & Safety

Overview

Ibuprofen (C13H18O2) is a widely used nonsteroidal anti-inflammatory drug (NSAID) sold under brand names including Advil and Motrin. With a molar mass of 206.28 g/mol, ibuprofen is a white crystalline powder that is practically insoluble in water but freely soluble in organic solvents like ethanol and acetone. It was discovered in the 1960s by Stewart Adams and John Nicholson at the Boots Company in the United Kingdom and has since become one of the most commonly used medications worldwide, available over the counter in most countries. Ibuprofen works by reversibly inhibiting both COX-1 and COX-2 cyclooxygenase enzymes, reducing the production of prostaglandins that cause inflammation, pain, and fever. This mechanism of action distinguishes it from acetaminophen, which lacks significant anti-inflammatory effects. Ibuprofen is used to treat headaches, dental pain, menstrual cramps, muscle aches, arthritis, and fever. It is on the World Health Organization's List of Essential Medicines. Structurally, ibuprofen is a propionic acid derivative with an isobutyl group attached to a para-substituted benzene ring. It contains a chiral center, meaning it exists as two enantiomers (R and S forms). Only the S-enantiomer is pharmacologically active, but the body can convert the R-form to the S-form, so the racemic mixture is sold commercially. This makes ibuprofen an excellent teaching example for chirality and stereochemistry. Ibuprofen is absorbed in the stomach and small intestine and is highly protein-bound in the bloodstream. Common side effects include stomach irritation and increased risk of gastrointestinal bleeding, especially with long-term use. It should be used cautiously in patients with kidney disease or cardiovascular conditions. GHS classifications include health hazard warnings. For chemistry students, ibuprofen connects multiple important topics: chirality and enantiomers, carboxylic acid functional groups, aromatic chemistry, enzyme inhibition mechanisms, and the relationship between molecular structure and pharmacological activity. The industrial synthesis of ibuprofen was revolutionized by the BHC Company's green chemistry process, which reduced the synthesis from six steps to three and won a Presidential Green Chemistry Challenge Award — making it a compelling case study in sustainable chemistry.

IUPAC Name

(RS)-2-(4-(2-methylpropyl)phenyl)propanoic acid

CAS Number

15687-27-1

PubChem CID

3672

Molecular Formula

C₁₃H₁₈O₂

Molar Mass

206.28 g/mol

State at STP

solid

Appearance

White crystalline powder

Physical Properties

Melting Point

76 °C

Density

1.03 g/cm³

Composition