Ibuprofen
Properties
| State | Solid (white crystalline) |
| Color | White to off-white |
| Solubility | Practically insoluble in water (<1 mg/mL); soluble in ethanol and acetone |
| Melting Point | 76°C |
| Boiling Point | 157°C (at 4 mmHg) |
About Ibuprofen
Ibuprofen is a 2-arylpropionic acid — the prototypical 'profen' NSAID — discovered in the early 1960s by Stewart Adams and John Nicholson at Boots, who were trying to find something gentler on the stomach than aspirin for rheumatoid arthritis. Adams famously tested an early 600 mg dose on himself to cure a hangover headache before a speech in Moscow. The molecule blocks both cyclooxygenase isoforms (COX-1 and COX-2), preventing the conversion of arachidonic acid to prostaglandin H2, which feeds into the PGE2 pathways that mediate inflammation, pain sensitization, and hypothalamic fever response. Ibuprofen has a stereocenter at the α-carbon, but only the S-(+)-enantiomer binds the COX active site productively. Curiously, you can still sell the cheaper racemate as a drug because human α-methylacyl-CoA racemase converts R-(-)-ibuprofen to the S-form in vivo via a CoA-thioester intermediate — about 60% of an oral R dose ends up inverted to active S. The industrial synthesis is a green-chemistry case study: Boots' original 1960s route used six stoichiometric steps with a stoichiometric AlCl3 Friedel-Crafts and a stoichiometric Darzens glycidic ester, throwing away most of the starting mass as salt waste. The BHC (Hoechst Celanese, now BASF) process introduced in 1991 replaced it with three catalytic steps — HF-catalyzed Friedel-Crafts acylation, Raney-Ni-catalyzed hydrogenation, and Pd-catalyzed carbonylation — at 99% atom economy, and won the 1997 Presidential Green Chemistry Challenge.
Where you'll encounter it
If you've ever swallowed an Advil for a hangover or a sore knee, you took on the order of 200–400 mg of a chiral drug whose body inverts the wrong enantiomer into the right one — a quirk that's saved the industry from ever needing to do an asymmetric synthesis at scale. A standard tablet hits peak plasma at about 25 mg/L within 90 minutes, which is the figure pharmacology students memorize for back-of-envelope dose calculations. In a pharmaceutical-process lab, the BHC three-step route is taught as the textbook example of atom economy: HF-catalyzed Friedel-Crafts on isobutylbenzene, Raney-Ni hydrogenation of the resulting ketone, and Pd-catalyzed carbonylation of the secondary alcohol — three steps, 99% atom economy, and a Presidential Green Chemistry Challenge award in 1997 that every green-chem syllabus references.
Common Uses
- Over-the-counter analgesic (200–400 mg q4-6h adult dose)
- Anti-inflammatory therapy for rheumatoid arthritis, osteoarthritis, gout flares
- Antipyretic in pediatric and adult fever management
- First-line treatment for primary dysmenorrhea (prostaglandin-mediated cramping)
- Closure of patent ductus arteriosus in preterm infants (IV ibuprofen lysine)
- Textbook case study for chirality, COX selectivity, and atom-economy green chemistry
Safety Information
GHS: H302 (harmful if swallowed at bulk doses), H318 (serious eye damage). Therapeutic risks at OTC doses: GI ulceration and bleeding from COX-1 inhibition in gastric mucosa (NSAID-induced gastropathy is responsible for thousands of hospitalizations annually in the US alone), renal afferent-arteriole constriction in dehydrated or volume-depleted patients, and modest cardiovascular risk at chronic high doses (FDA strengthened the boxed warning in 2015). Avoid concomitant low-dose aspirin antiplatelet — ibuprofen blocks aspirin's irreversible acetylation of platelet COX-1. Avoid in third-trimester pregnancy (premature ductus closure).
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals. We deliberately do not publish occupational exposure limits or other regulatory thresholds: those values are revised over time and differ between jurisdictions, so the only correct source is the current SDS and the regulations that apply where you work.