Quaternium-15

Quaternium-15 (systematic name: hexamethylenetetramine chloroallyl chloride) is a quaternary ammonium salt used as a surfactant and preservative in many cosmetics and industrial substances. It acts as an antimicrobial agent because it acts as a formaldehyde releaser, though doing so can also cause contact dermatitis, a symptom of an allergic reaction, especially in those with sensitive skin.
It can be found under a variety of names, most commonly those of the Dow Chemical Company: Dowicil 200 (cis isomer only), Dowicil 75 and Dowicil 100 (both a mix of cis and trans isomers).
Synthesis.
Quaternium-15 can be prepared by reacting hexamethylenetetramine with 1,3-dichloropropene to produce the product as a mixture of cis and trans isomers.
Applications.
The isolated cis-compound is used primarily in cosmetic applications, with a maximum permitted concentration in the EU of 0.2%. The mixed product (cis- and trans-) is used in a wider range of formulations such as: emulsifiable metal-cutting fluids; latex and emulsion paints; liquid floor polishes and floor waxes; glues and adhesives.
Safety concerns.
Quaternium-15 along with formaldehyde has been banned in the EU since 2017 and a bill is under consideration in the US.
Allergic reaction.
Quaternium-15 is an allergen, and can cause contact dermatitis in susceptible individuals. Many of those with an allergy to quaternium-15 are also allergic to formaldehyde. At low pHs it would be expected to release significant amounts of formaldehyde due to acid hydrolysis via the Delepine reaction.
Allergic sensitivity to quaternium-15 can be detected using a patch test.
It is the single most often found cause of allergic contact dermatitis of the hands (16.5% in 959 cases). In 2005–06, it was the fourth-most-prevalent allergen in patch tests (10.3%).
Cancer.
Some consumer cosmetics contain quaternium-15 for its antimicrobial properties. The American Cancer Society states that although quaternium-15 releases formaldehyde, a known carcinogen in laboratory test animals at relatively high doses, because the amount of formaldehyde released from these products is low, it is unclear that avoiding quaternium-15 in cosmetics provides any health benefits. Even so, Johnson & Johnson announced plans to phase out its use of quaternium-15 in cosmetic products by 2015 in response to consumer pressure.