2-(4-Isobutylphenyl)Propionic Acid

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2-(4-Isobutylphenyl)Propionic Acid


2-(4-Isobutylphenyl)propionic acid (two four eye-so-BYOO-tuhl-PHEEN-uhl PRO-pi-on-ik AS-id) is a colorless crystalline solid widely used as an analgesic and anti-inflammatory medication. It is most commonly known as ibuprofen, but is also known as α-methyl-4-(2-methylpropyl)benzeneacetic acid and 4-isobutyl-@alpha;-methylphenylacetic acid. It is also sold under a variety of trade names, including Aches-n-Pain®, Advil®, Andran®, Antagil®, Antarene®, Excedrin IB®, Genpril®, Ibuprin®, Medipren®, Midol®, Motrin®, Nuprin®, PediaProfen®, Rufen®, and Vicoprofen®.



Ibuprofen; see Overview for more names




Carbon, hydrogen, oxygen


Organic acid




206.28 g/mol


76°C (169°F)


Not applicable; decomposes above melting point


Slightly soluble in water; soluble in most organic solvents

Ibuprofen was developed by researchers at the Boots Company, a British drug manufacturer, in the early 1960s. Those researchers had found that the anti-inflammatory property of aspirin was due to the presence of a carboxylic acid (-COOH) group in the compound. They searched for other carboxylic acids that might have similar properties and, after testing more than 600 compounds, discovered that ibuprofen met that criterion. It was twice as effective as acetylsalicylic acid (aspirin), the standard against which they were testing their products. They initially called their discovery "Brufen."

In 1974, Boots licensed the Upjohn Company in the United States to begin making a commercial version of Brufen. Upjohn called its product Motrin and marketed the compound primarily to people with arthritis. It soon became a popular drug with both doctors and patients, who found they were able to control the pain of arthritis with a non-addictive product that was easier on the stomach than aspirin.

Boots also entered the U.S. market several years later, selling ibuprofen under the trade name of Rufen. A number of other drug companies were eager to begin marketing their version of ibuprofen, and when the U.S. Food and Drug Administration approved ibuprofen for over-the-counter sales, they were ready. Whitehall Laboratories introduced Advil and Upjohn and Bristol-Meyers jointly released Nuprin. After Boots' patent ran out in 1985, several other drug manufacturers began producing their own versions of the popular pain-killing and anti-inflammatory product.


The original method for making ibuprofen developed by Boots researchers begins with 2-methylpropylbenzene, a compound with a four-carbon methylpropyl group attached to a benzene ring. 2-methylpropybenzene is a readily available product with a molecular structure quite similar to that of ibuprofen. Then, in a series of six steps, various groups of atoms are added, removed, or transposed to produce the 2-(4-isobutylphenyl)propionic acid molecule.

Other methods for preparing ibuprofen have also been developed. One of the most recent procedures has been invented by green chemists. Green chemists are chemists who look for methods of making chemical compounds that are less wasteful of raw materials, more sensitive to environmental concerns, and less hazardous to human health. The green chemistry method of making ibuprofen also begins with 2-methylpropylbenzene, but uses different catalysts and fewer steps to produce ibuprofen. Overall, the green method of making ibuprofen is twice as efficient (half as much waste products) as the original Boots method.


Interesting Facts

Some evidence suggests that taking ibuprofen for two years or more may reduce the risk of developing Alzheimer's disease.

Ibuprofen is a nonsteroidal anti-inflammatory drug, or NSAID. The term nonsteroidal indicates that ibuprofen is not a steroid, a common class of drugs used to reduce inflammation and swelling. Scientists believe that ibuprofen works by inhibiting the enzyme cyclooxygenase (COX), which converts arachidonic acid to prostaglandins. Arachidonic acid is a naturally occurring fatty acid that is used to build a number of important biochemical compounds, including the prostaglandins. The prostaglandins are involved in the transmission of pain impulses throughout the nervous system. If the COX enzyme is prevented from functioning, arachidonic acid can not be converted into prostaglandins, and pain messages will not be transmitted.

Ibuprofen is especially effective in treating certain kinds of pain and inflammation, including those associated with menstrual cramps, various kinds of arthritis, headaches and migraines, pain from injuries and surgery, and discomfort associated with influenza and gout.

The major risk associated with use of ibuprofen is stomach irritation. The inventors of ibuprofen had hoped to find a substance that causes less stomach irritation than aspirin. Ibuprofen does seem to cause fewer gastrointestinal problems than does aspirin. Nevertheless, it can still cause severe problems in some patients, especially those who take large doses. Common complaints from the use of ibuprofen include nausea, stomach pain, and diarrhea. Patients who are especially sensitive or who take high doses of ibuprofen for long periods may experience damage to the stomach lining.

Words to Know

a substance the relieves pain.
a material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure.
the practice of making chemical compounds that are less wasteful of raw materials, more sensitive to environmental concerns, and less hazardous to human health.

As with any drug, some patients should avoid taking ibuprofen entirely. These include individuals with heart or kidney problems, people who are taking so-called "blood thinners," pregnant women during the last three months of pregnancy, people with asthma, and people who are allergic to aspirin.


"Ibuprofen." Chemical Land 21. http://www.chemicalland21.com/arokorhi/lifescience/phar/IBUPROFEN.htm (accessed on November 3, 2005).

"Ibuprofen—Oral." MedicineNet.com. http://www.medicinenet.com/ibuprofen-oral/article.htm (accessed on November 3, 2005).

Rainsford, K. D., ed. Ibuprofen: A Critical Bibliographic Review. Bethesda, MD: CCR Press, 1999.

See AlsoAcetylsalicylic Acid

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2-(4-Isobutylphenyl)Propionic Acid

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