What molecule am I?
Allura Red AC (AR), also called FD&C Red No. 40, is a synthetic azo dye with a wide range of uses. As a food dye, it often goes by the designation E129 or C.I. Food Red 17.
AR appeared in the chemical literature in 1971, when Daniel M. Marmion at Allied Chemical (Buffalo, NY) published analytical methods for the then-new dye in foods such as ice cream, “wieners”, and hard candy. Allied Chemical was the developer of the product. The same year, the dye was listed in the Federal Register as a color additive for food and drug use subject to US Food and Drug Administration certification. FDA registration for use in food, drugs, and cosmetics rapidly ensued.
According to 1970 US Patent 3,519,617 to inventors Gustav E. Rast and Russell I. Steiner at Allied Chemical, AR and similar compounds can be synthesized by coupling a diazotized 5-alkoxy-2-alkylsulfanilic acid with 2-naphthol-6-sodium sulfonate2. This basic method is still in use.
AR replaced amaranth3 (FD&C Red No. 2) and erythrosine4 (FD&C Red No. 3) as red colorants, both of which have since been banned by FDA. But now AR has also come under scrutiny. In 2022, Waliul I. Khan and 13 colleagues at McMaster University (Hamilton, ON) wrote that, chronic exposure to AR, in combination with intestinal serotonin5, promoted susceptibility to colitis in laboratory mice. The authors stated that this result warrants investigations of the effects of other food dyes on colitis and human studies on AR.
This past April, the Trump FDA, under Robert F. Kennedy, Jr., announced that it would seek to ban eight synthetic dyes, including AR, in food.
1. SciFinder name: 2-naphthalenesulfonic acid, 6-hydroxy-5-[2-(2-methoxy-5-methyl-4-sulfophenyl)diazenyl]-, sodium salt (1:2).
2. CAS Reg. No. 135-76-2.
3. CAS Reg. No. 915-67-3.
4. CAS Reg. No. 16423-68-0.
5. CAS Reg. No. 50-67-9.
Allura Red AC hazard information
| Hazard class* | GHS code and hazard statement |
|---|---|
| Not a hazardous substance or mixture |
*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals.
Tolebrutinib1 is a developmental drug for treating Bruton's tyrosine kinase–related diseases such as multiple sclerosis (MS). It was first described in 2016 in world patent application WO2016196840 to David Goldstein and Timothy D. Owens at Principia Biopharma (South San Francisco, CA; acquired by Sanofi [Paris] in 2020).
This past April, two articles reported the results of studies involving tolebrutinib. Robert J. Fox at Cleveland Clinic and collaborators at North American and European institutions, including Sanofi, conducted a >2-year, 1131-participant phase 3 trial of the drug versus placebo against nonrelapsing secondary progressive MS. They found that tolebrutinib significantly reduced disability progression in the treated group.
Jiwon Oh at the University of Toronto and coauthors worldwide reported on two >2-year phase 3 trials involving almost 2000 participants. The trials compared the effects of tolebrutinib with those of teriflunomide2, an older MS drug, against relapsing MS. Although tolebrutinib showed a lower relapse rate than teriflunomide, the difference was not statistically significant. Teriflunomide, however, is known to have serious adverse side effects.
1. CAS Reg. No. 1971920-73-6.
2. CAS Reg. No. 163451-81-8.
Molecule of the Future
Once a month we bring you a newly discovered or developed molecule that has important implications for the future of chemistry or society in general. Look for it the third week of each month. Learn more about this month's Molecule of the Future.
We're looking for more molecules of the future!
Do you have a suggestion for the next molecule of the future? Send your idea to MOTW.
This molecule was suggested by a reader. We present almost all of the molecules suggested by our readers. If you have a molecule you would like us to consider, please send us a message. And thank you for your interest in Molecule of the Week! —Ed.
Allura Red AC
fast facts
| CAS Reg. No. | 25956-17-6 |
| Empirical formula | C18H14N2Na2O8S2 |
| Molar mass | 496.42 g/mol |
| Appearance | Dark red crystals or powder |
| Melting point | >300 ºC |
| Water solubility | 220 g/L (25 °C) |
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.
Molecule of the Week needs your suggestions!
If your favorite molecule is not in our archive, please send us a message. The molecule can be notable for its current or historical importance or for any quirky reason. Thank you!
Stay Ahead of the Chemistry Curve
Learn how ACS can help you stay ahead in the world of chemistry.
