What molecule am I?
Stearic acid, formally octadecanoic acid, is a fatty acid that is present as a component of triglyceride esters in many natural sources. It occurs most widely in animal fats and products made from them such as butterfat, cheeses, and tallow. Triglycerides in plant-based materials such as palm and coconut oil and cocoa and shea butter also contain stearic acid.
The molecule appeared in the chemical literature in 1879, when Thomas Carnelley* and W. Carleton Williams at Owens College (Manchester, UK) determined its boiling point and those of other chemicals by a curious method that involved measuring the melting points of their salts. Strangely titled “On the boiling points of certain metals and metallic salts” (“melting points” was probably meant), the article reported boiling points that are close to today’s accepted values.
On the other hand, an 1894 article by W. E. Garrigues at Duquesne Chemical Laboratory (Pittsburgh) discussed the difficulties of measuring the melting points of fatty substances, which he called “candle material”. Adapting a technique used to measure the melting temperatures of paraffin waxes produced in oil refineries, Garrigues went to great lengths to determine the melting points of stearic, palmitic1, and oleic2 acids and obtained remarkably reproducible results. The only problem was that his value for stearic acid’s melting point was ≈15 °C lower than the one that eventually was measured correctly.
Stearic acid and its derivatives are found in dozens of food and household products. In addition to the foods mentioned above, fats (triglycerides) containing stearic acid are used in manufacturing baked goods, ice cream, candies, and other desserts. Because stearic acid is a saturated fatty acid, many consumers avoid consuming foods that contain it and its cousins, especially palmitic acid.
Stearic acid salts and esters are ingredients of a wide range of cosmetics, soaps, detergents, and other familiar products. In industry, many of the same compounds are used in lubricants, textile softeners, casting materials (e.g., plaster), polishes, and of course, candles.
1. CAS Reg. No. 57-10-3.
2. CAS Reg. No. 112-80-1.
Stearic acid hazard information*
| Hazard class** | GHS code and hazard statement | |
|---|---|---|
Skin corrosion/irritation, | H315—Causes skin irritation |  |
*Most safety data sheets state “not a hazardous substance or mixture”.
**Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.
Orforglipron1 is a small-molecule, orally active, nonpeptide glucagon-like peptide-1 (GLP-1) receptor agonist undergoing clinical development by Eli Lilly (Indianapolis) for type 2 diabetes and obesity. It was discovered by Chugai Pharmaceutical (Tokyo), which licensed it to Lilly in 2018. In 2020, Yoshiyuki Suzuki and collaborators at Chugai, Lilly, and ConfometRx (Santa Clara, CA) described the structural basis for GLP-1 activation by orforglipron, then known as LY3502970.
The results of two clinical trials on orforglipron were published earlier this year. In June, Julio Rosenstock at Velocity Clinical Research Center at Medical City Dallas and coauthors at Lilly and other medical facilities disclosed that the drug significantly reduced the glycated hemoglobin level in adults with early type 2 diabetes over a period of 40 weeks.
In September, Sean Wharton at McMaster University (Hamilton, ON), York University (Toronto), and Wharton Weight Management Clinic (Burlington, ON) and coauthors at Lilly and other facilities worldwide reported that 72-week treatment with orforglipron led to significantly greater reductions than placebo in the body weight of obese adults.
Also in June, Reuters reported on another Lilly developmental obesity drug, eloralintide2, helped patients lose as much as 11.5% of their body weight in 12 weeks in an early-stage study.
1. CAS Reg. No. 2212020-52-3
2. CAS Reg. No. 2883634-40-8.
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Stearic acid fast facts
| CAS Reg. No. | 57-11-4 |
| SciFinder name | Octadecanoic acid |
| Empirical formula | C18H36O2 |
| Molar mass | 284.48 g/mol |
| Appearance | White waxy solid |
| Melting point | 69–71 °C |
| Boiling point | 361–383 °C (dec.) |
| Water solubility | ≈3 mg/L (20 °C)a |
a. Literature reports vary widely.
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