Lithium 12-hydroxystearate

December 16, 2019
I’m a soap, but one that you’re not likely to find in your bathtub.
What molecule am I?
Image of Lithium 12-hydroxystearate 3D Image of Lithium 12-hydroxystearate

Lithium 12-hydroxystearate is a fatty acid salt commonly known as a “lithium soap”. It is the most common soap used to stabilize and thicken lubricating greases. Lithium salts are generally preferred to soaps with other counterions such as sodium, calcium, and barium.

Recently, Ryan Gordon and Cameron F. Abrams* at Drexel University (Philadelphia) and Spencer T. Stober* at ExxonMobil Research and Engineering (Annandale, NJ) investigated the counterion effects of lithium and sodium 12-hydroxystearate and 12-hydroxystearic acid on the structures of their aggregates, which reflect their rheological properties.

Using quantum mechanical calculations and molecular dynamics simulations, the authors found that the lithium salt formed the most efficiently packed aggregates. This finding is consistent with the compound’s relatively high melting temperature and the high frequency of hydroxyl hydrogen bonding in its aggregates.

According to the authors, these results “may be a factor that makes greases produced from lithium 12-hydroxystearate exhibit higher performance.”

The increasing use of lithium batteries, especially in electric vehicles and electrical power plants, has put pressure on the supply of lithium ores. The resulting unpredictable ore prices have caused some misery to the battery and lithium soap industries. 

[Many thanks to Nancy McGuire for assistance with this article—ED].

Lithium 12-hydroxystearate hazard information

GHS classification*: skin corrosion/irritation, category 2
H315—Causes skin irritation Chemical Safety Warning
GHS classification: serious eye damage/eye irritation, category 2A
H319—Causes serious eye irritation  Chemical Safety Warning
GHS classification: specific target organ toxicity, single exposure, respiratory tract irritation, category 3
H335—May cause respiratory irritation Chemical Safety Warning

**Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

Lithium 12-hydroxystearate fast facts

CAS Reg. No. 7620-77-1
Empirical formula C18H35LiO3
Molar mass 306.42 g/mol
Appearance White crystals or powder
Melting point 200–220 ºC
Water solubility ≈200 mg/L (est.)
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