Octyl methoxycinnamate or ethylhexyl methoxycinnamate ( INCI) or octinoxate ( USAN), trade names Eusolex 2292 and Uvinul MC80, is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

that is an ingredient in some

sunscreen Sunscreen, also known as sunblock, sun lotion or sun cream, is a photoprotection, photoprotective topical product for the Human skin, skin that helps protect against sunburn and prevent skin cancer. Sunscreens come as lotions, sprays, gels, fo ...

s and lip balms. It is an

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

formed from methoxycinnamic acid and

2-ethylhexanol 2-Ethylhexanol (abbreviated 2-EH) is an organic compound with the chemical formula . It is a branched, eight-carbon chiral alcohol. It is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. It is produced on a l ...

. It is a liquid that is insoluble in water. It is primarily used in sunscreens and other cosmetics to absorb

UV-B Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...

rays from the

sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, protecting the skin from damage. It is also used to reduce the appearance of scars.

Uses

Octyl methoxycinnamate is the most common

active ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals. ...

in sunscreens for protection against UV-B rays. It may be combined with

oxybenzone Oxybenzone or benzophenone-3 or BP-3 (trade names Milestab 9, Eusolex 4360, Escalol 567, KAHSCREEN BZ-3) is an organic compound belonging to the class of aromatic ketones known as benzophenones. It takes the form of pale-yellow crystals that are ...

and

titanium oxide Titanium oxide may refer to: * Titanium dioxide (titanium(IV) oxide), TiO2 * Titanium(II) oxide (titanium monoxide), TiO, a non-stoichiometric oxide * Titanium(III) oxide (dititanium trioxide), Ti2O3 * Ti3O * Ti2O * δ-TiOx (x= 0.68–0.75) * Ti ...

. Studies have evaluated the efficacy of octyl methoxycinnamate in preventing postoperative peritoneal adhesions and determined that octyl methoxycinnamate covering peritoneal surfaces decreases adhesion formation. This effect is more notable when octyl methoxycinnamate is applied before the induction of trauma. Chromophore groups, such as C=C, C=O, and O-N=O, have loosely held electrons that are excited by radiation. Hence, octyl methoxycinnamate is able to absorb radiation when the electron energy level is increased to an excited state.

Properties

The UV spectra of octyl methoxycinnamate contains a maximum at 310 nm.

Synthesis

Olefin metathesis has been widely studied. One of the synthesis pathways for octyl methoxycinnamate includes cross metathesis. The high efficiency of the nitro-Grela catalyst has been used in the cross metathesis of ''trans''-anethole with 2-ethylhexyl acrylate to produce octyl methoxycinnamate (86% yield).

Safety studies

One study performed in 2000 raised safety concerns about octyl methoxycinnamate by demonstrating toxicity to mouse cells at concentrations lower than typical levels in sunscreens. However, another study concluded that octyl methoxycinnamate and other sun screening agents do not penetrate the outer skin in sufficient concentration to cause any significant toxicity to the underlying human

keratinocyte Keratinocytes are the primary type of cell found in the epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells. Basal cells in the basal layer (''stratum basale'') of the skin are sometimes referre ...

s. Estrogenic and neurological effects were noted in laboratory animals at concentrations close to those experienced by sunscreen users and were also shown

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

. Octyl methoxycinnamate has been shown to be light sensitive with a decrease in UV absorption efficiency upon light exposure. This degradation causes formation of the Z-octyl-p-methoxycinnamate from the E-octyl-p-methoxycinnamate. In contrast, the OMC does not show degradation when kept in darkness for extended periods of time. A study carried out in 2017 by the Research Centre for Toxic Compounds in the Environment at Masaryk University, Czech Republic, indicates that octyl methoxycinnamate (EHMC) may damage human cell DNA. When exposed to sun rays, the spatial arrangement of its molecules changes and isomerisation takes place. While until now only unchanged EHMC has been researched, Massaryk University researchers focused on its isomers and found out that it has a significant genotoxic effect under lab conditions. It means that it may potentially damage human DNA and cause genome mutations which may lead to serious health risks. In swimming pools with hypochlorite in aqueous solution, octyl methoxycinnamate has been shown to produce chlorine-substituted intermediates. The chlorination intermediates of octyl methoxycinnamate demonstrated weak mutagenic effects on the Salmonella typhimurium TA 100 strain. The reactions depended on the pH, compound structures, and chlorine dose.

Ecological damage

Concern about effects on

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...

s resulted in a bill in the state legislature of Hawaii to limit use of sunscreens containing octyl methoxycinnamate and

. For the same reasons, the government of

Palau Palau, officially the Republic of Palau, is an island country in the Micronesia subregion of Oceania in the western Pacific Ocean. The Republic of Palau consists of approximately 340 islands and is the western part of the Caroline Islands ...

signed a law in 2018 (becoming effective in 2020) that restricted the sale and use of sunscreen and skincare products that contain a list of ten different chemicals, including the UV filters octyl methoxycinnamate, oxybenzone and octocrylene, with fines of for retailers who violate the law and the power to confiscate such products from non-commercial users.

Stereochemistry

Octinoxate contains a stereocenter and a double bond. It has the following stereoisomersS. Pattanaargson, T. Munhapol, P. Hirunsupachot, P. Luangthongaram (ed.): '' Photoisomerization of octyl methoxycinnamate. '' In: '' Journal of Photochemistry and Photobiology A: Chemistry '', Elsevier Verlag, vol. 161, no. 2-3, 30 January 2004, pp. 269-274.Process for producing 2-ethylhexanol
CL = DE 3530839A1
29 August 1985
EP 0216151 B1
20 August 1986. Therefore, octinoxate could consist of the following four stereoisomers:

References

{{Sunscreening agents Cinnamate esters 4-Methoxyphenyl compounds Sunscreening agents 2-Ethylhexyl esters