Denatonium

Denatonium benzoate
IUPAC name phenylmethyl-[2- [(2,6-dimethylphenyl)amino]- 2-oxoethyl]-diethylammonium benzoate
Identifiers
CAS number	3734-33-6 Y
PubChem	19518
ChemSpider	18392 Y
UNII	M5BA6GAF1O Y
Jmol-3D images	Image 1
SMILES O=C(Nc1c(cccc1C)C)C[N+](Cc2ccccc2)(CC)CC.[O-]C(=O)c1ccccc1
InChI InChI=1S/C21H28N2O.C7H6O2/c1-5-23(6-2,15-19-13-8-7-9-14-19)16-20(24)22-21-17(3)11-10-12-18(21)4;8-7(9)6-4-2-1-3-5-6/h7-14H,5-6,15-16H2,1-4H3;1-5H,(H,8,9) Y Key: VWTINHYPRWEBQY-UHFFFAOYSA-N Y InChI=1/C21H28N2O.C7H6O2/c1-5-23(6-2,15-19-13-8-7-9-14-19)16-20(24)22-21-17(3)11-10-12-18(21)4;8-7(9)6-4-2-1-3-5-6/h7-14H,5-6,15-16H2,1-4H3;1-5H,(H,8,9) Key: VWTINHYPRWEBQY-UHFFFAOYAY
Properties
Molecular formula	C28H34N2O3
Molar mass	446.581
Appearance	white crystalline
Melting point	163-170 °C
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Denatonium, usually available as denatonium benzoate (under trade names such as BITTER+PLUS,Bitrex or Aversion) and as denatonium saccharide, is the bitterest chemical compound known; with bitterness thresholds of 0.05 ppm for the benzoate and 0.01 ppm for the saccharide^[1]. It was discovered in 1958 during research on local anesthetics by Macfarlan Smith of Edinburgh, Scotland, and registered under the trademark Bitrex.^[2] 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 to prevent accidental ingestion. Denatonium is used in denatured alcohol,^[3] 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.^[4]

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.

Applications

The bitterness of the compound guides most applications of denatonium. Denatonium benzoate is used to denature ethanol so that it is not taxed as an alcoholic beverage. 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 also discourages consumption of harmful alcohols like methyl alcohol, and additives like ethylene glycol. Denatonium is also 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 canned air dusters) to discourage inhalant abuse of the volatile vapors.

Since 1995, when the U.S. State of Oregon required that denatonium benzoate be added to antifreeze and windshield washer fluid, the compound has been increasingly found in these substances throughout the world. The addition is credited with saving children and animals who might otherwise drink sweet antifreeze or wiper fluid and get ethylene glycol or methanol poisoning respectively.

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,^[5] as humans are able to detect denatonium at much lower concentrations than rodents.^[6] 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.^{[citation needed]}

References

1. ^ "Final Report Study of Aversive Agents". Consumer Product Safety Commission United States of America. 18 November 1992. http://www.cpsc.gov/LIBRARY/FOIA/foia99/os/aversive.pdf. Retrieved 15 November 2010. 
2. ^ "Bitrex(R) — Branded Denatonium Benzoate". Macfarlan Smith. http://www.macsmith.com/index.php?page=bitrex. Retrieved 2010-05-09. 
3. ^ "Ethanol Denaturants". The Online Distillery Network. 1993-11-22. http://www.distill.com/specs/EU2.html. 
4. ^ "Final Report Study of Aversive Agents". Consumer Product Safety Commission United States of America. 18 November 1992. http://www.cpsc.gov/LIBRARY/FOIA/foia99/os/aversive.pdf. Retrieved 15 November 2010. 
5. ^ "Rats - Rat Poison & Rat Bait Stations". Pestcontrolshop.co.uk. http://www.pestcontrolshop.co.uk/acatalog/rats.html. Retrieved 2011-01-17. 
6. ^ The distinctiveness of ionic and nonionic bitter stimuli. Frank ME, Bouverat BP, MacKinnon BI, Hettinger TP. Physiol Behav. 2004 Jan;80(4):421-31.