Denatonium

Denatonium benzoate
Skeletal formulas of the denatonium cation...
...and the benzoate anion
Ball-and-stick models of the both ions in denatonium benzoate
Names
IUPAC name
phenylmethyl-[2- [(2,6-dimethylphenyl)amino]- 2-oxoethyl]-diethylammonium benzoate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.020.996
UNII
Properties
C28H34N2O3
Molar mass 446.581
Appearance white crystalline
Melting point 163 to 170 °C (325 to 338 °F; 436 to 443 K)
Hazards
R-phrases (outdated) R22 R36 R37 R38
S-phrases (outdated) S26 S36[1]
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
1
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Denatonium, usually available as denatonium benzoate (under trade names such as BITTERANT-b, BITTER+PLUS, Bitrex or Aversion) and as denatonium saccharide (BITTERANT-s), is the most bitter chemical compound known, with bitterness thresholds of 0.05 ppm for the benzoate and 0.01 ppm for the saccharide.[2] It was discovered in 1958 during research on local anesthetics by MacFarlan Smith of Edinburgh, Scotland, and registered under the trademark Bitrex.[3]

Dilutions of as little as 10 ppm are unbearably bitter to most humans. Denatonium salts are usually colorless and odorless solids but are often traded as solutions. They are used as aversive agents (bitterants) to prevent inappropriate ingestion. Denatonium is used in denatured alcohol,[4] antifreeze, nail biting preventions, respirator mask fit-testing, animal repellents, liquid soaps, and shampoos. It is not known to pose any long-term health risks.[2]

Structure and physical properties

Denatonium is a quaternary ammonium cation. It is a compound of a salt with an inert anion like benzoate or saccharide. The structure of denatonium is related to the local anesthetic lidocaine, differing only by the addition of a benzyl group to the amino nitrogen. Other similar compounds are procaine and benzocaine.[5]

One of the chemical names for the compound is Lidocaine benzylbenzoate, although denatonium only denotes the quaternary ammonium cation species itself, and does not necessitate the benzoate counterion.

Biochemistry

Denatonium in humans is recognized by eight distinct bitter taste receptors: TAS2R4, TAS2R8, TAS2R10, TAS2R39, TAS2R43, TAS2R16, TAS2R46, TAS2R47, with TAS2R47 being by far the most sensitive to the compound.[6][7]

Denatonium can act as a bronchodilator by activating bitter taste receptors in the airway smooth muscle.[8]

Applications

The bitterness of the compound guides most applications of denatonium. Denatonium benzoate is used to denature ethanol so that it is not treated as an alcoholic beverage with respect to taxation and sales restrictions. One designation in particular, SD-40B, indicates that ethanol has been denatured using denatonium benzoate. The common name for this chemical, denatonium, alludes to this application.

Denatonium is commonly included in placebo medications used in clinical trials to match the bitter taste of certain medications.

Denatonium also discourages consumption of harmful alcohols like methanol, and additives like ethylene glycol. Denatonium is used in rubbing alcohol as an inactive ingredient. It is also added to many kinds of harmful liquids including solvents (such as nail polish remover), paints, varnishes, toiletries and other personal care items, special nail polish for preventing nail biting, and various other household products. It is also added to less hazardous aerosol products (such as gas dusters) to discourage inhalant abuse of the volatile vapors.

In 1995, the U.S. state of Oregon required that denatonium benzoate be added to products containing sweet-tasting ethylene glycol and methanol such as antifreeze and windshield washer fluid to prevent poisonings of children and animals.[9] In December 2012, U.S. manufacturers voluntarily agreed to add denatonium benzoate to antifreeze sold nationwide.[10]

Animals are known to have different sensitivities to the effects of denatonium. It is used in some animal repellents (especially for such large mammals as deer). It has been used to safeguard rat poisons from human consumption,[11] as humans are able to detect denatonium at much lower concentrations than rodents.[12] However, some cats have been known to be tempted by them—it may not be as effective a deterrent for cats as it is for humans, or perhaps some cats are not deterred due to a genetic factor similar to that affecting human perceptions of the taste of phenylthiocarbamide.

The video game company Nintendo uses denatonium benzoate on their physical Game Cards for their hybrid gaming console, the Nintendo Switch. The aversive agent is coated on the game cartridges to deter children from ingesting them.[13]

See also

References

  1. "Safety & Documentation". D5765 Aldrich: Denatonium benzoate ≥98%. Sigma-Aldrich Co. LLC. Retrieved 10 September 2014.
  2. 1 2 Final Report Study of Aversive Agents (PDF). Consumer Product Safety Commission United States of America. 18 November 1992. Archived from the original (PDF) on 16 June 2011. Retrieved 15 November 2010.
  3. "Bitrex(R) — Branded Denatonium Benzoate". Macfarlan Smith. Retrieved 2010-05-09.
  4. "Ethanol Denaturants". The Online Distillery Network. 1993-11-22.
  5. Holvoet, Jean-Patrick. "Denatonium". Sentinalco. Retrieved 2 October 2015.
  6. Meyerhof, W.; Batram, C.; Kuhn, C.; Brockhoff, A.; Chudoba, E.; Bufe, B.; Appendino, G.; Behrens, M. (2009). "The Molecular Receptive Ranges of Human TAS2R Bitter Taste Receptors". Chemical Senses. 35 (2): 157–170. PMID 20022913. doi:10.1093/chemse/bjp092.
  7. "BitterDB - Denatonium benzoate". Hebrew University of Jerusalem. Retrieved 11 June 2013.
  8. Deshpande, D. A.; Wang, W. C. H.; McIlmoyle, E. L.; Robinett, K. S.; Schillinger, R. M.; An, S. S.; Sham, J. S. K.; Liggett, S. B. (2010). "Bitter taste receptors on airway smooth muscle bronchodilate by localized calcium signaling and reverse obstruction". Nature Medicine. 16 (11): 1299–1304. PMC 3066567Freely accessible. PMID 20972434. doi:10.1038/nm.2237.
  9. Mullins ME, Zane Horowitz B (June 2004). "Was it necessary to add Bitrex (denatonium benzoate) to automotive products?". Veterinary and human toxicology. 46 (3): 150–2. ISSN 0145-6296. PMID 15171494.
  10. "Antifreeze and Engine Coolant Being Bittered Nationwide". Consumer Specialty Products Association. 13 December 2012. Archived from the original on 28 December 2012. Retrieved 30 June 2016.
  11. "Rats - Rat Poison & Rat Bait Stations". Pestcontrolshop.co.uk. Archived from the original on 2011-01-06. Retrieved 2011-01-17.
  12. Frank ME, Bouverat BP, MacKinnon BI, Hettinger TP. The distinctiveness of ionic and nonionic bitter stimuli. Physiol Behav. 2004 Jan;80(4):421-31. doi:10.1016/j.physbeh.2003.09.009
  13. Kwame Opam (1 March 2017). "Yes, Nintendo Switch cartridges taste terrible". theverge.com.
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