Cetyltrimethylammonium bromide

February 20, 2023
I’m a surfactant and antiseptic.
What molecule am I?
2D graphic of Cetyltrimethylammonium bromide (CTAB) 3D graphic of Cetyltrimethylammonium bromide (CTAB)

Cetyltrimethylammonium bromide (CTAB), sometimes called cetrimonium bromide, is a quaternary ammonium salt with surface-active and antiseptic properties. It was mentioned in the chemical literature as early as 1936, when G. S. Hartley*, B. Collie, and C. S. Samis at University College London studied transport numbers of paraffin-chain salts in aqueous solutions.

In 1946, R. S. Shelton and co-workers at the William S. Merrell Company1 (Cincinnati) reported a synthesis of CTAB from cetyl (hexadecyl) bromide and trimethylamine. They prepared CTAB and several other compounds during a study of the efficacy of quaternary ammonium salts as what they termed “germicides”.

Today, in addition to its use as a topical antiseptic, CTAB has applications in medicine as an apoptosis-promoting anticancer agent, and in protein electrophoresis, DNA extraction buffer systems, and nanoparticle synthesis. In a report this month, Jonathan Boltersdorf, Taylor J. Woehl, and coauthors at the University of Maryland (College Park), the Army Research Laboratories (Adelphi, MD), General Technical Services (Wall Township, NJ), and the Naval Surface Warfare Center (Crane, IN) used CTAB as a surfactant in their examination of silver photodeposition onto gold nanorods.

1. After a long series of mergers and acquisitions, William S. Merrell is now part of Sanofi.

CTAB hazard information*

Hazard class**GHS code and hazard statement
Acute toxicity, oral, category 4H302—Harmful if swallowedChemical Safety Warning
Skin corrosion/irritation, category 2H315—Causes skin irritationChemical Safety Warning
Serious eye damage/eye irritation, category 1H318—Causes serious eye damageChemical Safety Warning
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3H335—May cause respiratory irritationChemical Safety Warning
Specific target organ toxicity, repeated exposure, oral, gastrointestinal tract, category 2H373—May cause damage to organs (gastrointestinal tract) through prolonged or repeated exposure if swallowedChemical Safety Warning
Short-term (acute) aquatic hazard, category 1H400—Very toxic to aquatic lifeChemical Safety Warning
Long-term (chronic) aquatic hazard, category 1H410—Very toxic to aquatic life with long-lasting effectsChemical Safety Warning

*Compilation of two safety data sheets.
**Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.

Molecule of the Future

Analgesics, or pain killers, function as agonists for adenosine A1 receptors (A1Rs), which are ubiquitous in the body. But conventional analgesics, including opioids, have undesirable side effects, such as sedation, bradycardia (slow heart rate), hypotension, and respiratory depression.

Last July, Mark J. Wall, Graham Ladds, Bruno G. Frengueli, and collaborators at the Universities of Warwick and Cambridge (both in the UK) and other institutions reported that, in animal testing, the molecule benzyloxycyclopentyladenosine1 (BnOCPA) is a selective agonist for A1Rs that elicits analgesia without cardiorespiratory depression. Unlike opioids, BnOCPA is nonaddictive and has few side effects. 

Molecule of the Future: benzyloxycyclopentyladenosine

The synthesis of BnOCPA was first described in a 2005 US patent application by inventors Elfatih Elzein and Jeff Zablocki, assigned to CV Therapeutics (Palo Alto, CA).

1. CAS Reg. No. 872693-38-4.

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CTAB fast facts

CAS Reg. No.57-09-0
SciFinder nomenclature1-Hexadecanaminium, N,N,N-trimethyl-, bromide
Empirical formulaC19H42BrN
Molar mass364.45 g/mol
AppearanceWhite crystals or powder
Melting point248–251 °C
Water solubility36 g/L

MOTW update

Xylan was the Molecule of the Week for August 8, 2022. It is a hemicellulose, one of the three types of fibers found in plants. This month, Bjørge Westereng, Kirsi S. Mikkonen, Tiina Nypelö, and colleagues at three Scandinavian universities reviewed the possibilities of using wood hemicelluloses, including xylan, as food ingredients. Among other uses, they report that wood hemicelluloses are structurally similar to those obtained from food crops and explore their potential as dietary fibers. Hemicelluloses from agricultural waste also can be used to manufacture valuable products such as chemicals and packaging materials.

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