Source: Wikipedia, the free encyclopedia.
6PPD skeletal.svg
Preferred IUPAC name
Other names
  • N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine
  • 6PPD
3D model (
ECHA InfoCard
100.011.222 Edit this at Wikidata
EC Number
  • 212-344-0
UN number 3077
  • InChI=1S/C18H24N2/c1-14(2)13-15(3)19-17-9-11-18(12-10-17)20-16-7-5-4-6-8-16/h4-12,14-15,19-20H,13H2,1-3H3
  • CC(C)CC(C)NC1=CC=C(C=C1)NC2=CC=CC=C2
Molar mass 268.404 g·mol−1
Appearance brown or violet solid powder
Density 1.07
Melting point 45 °C (113 °F; 318 K)
Boiling point 260 °C (500 °F; 533 K)
log P 3.972
GHS labelling:
GHS09: Environmental hazard
H302, H317, H360, H410
P201, P202, P261, P264, P270, P272, P273, P280, P281, P301+P312, P302+P352, P308+P313, P321, P330, P333+P313, P363, P391, P405, P501
Flash point 204 °C (399 °F; 477 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

6PPD is an

p-phenylenediamine (PPD) additives used to protect various rubber materials.[2]


6PPD is prepared by


Environmental impact

6PPD is converted by ozone to a quinone compound 6PPD-quinone (6PPD-Q, CAS:2754428-18-5).

6PPD ozone-oxidation overview.svg

Despite 6PPD being used in tires since the mid 1960s, this transformation was first identified in 2020,

freshwater streams.[6][7][8]

A 2022 study also identified the toxic impact on species like brook trout and rainbow trout.[9] The published lethal concentrations are:[9][10]

It is not known why the ozone-oxidised 6PPD is toxic to coho salmon. The

Washington Department of Ecology, Washington State University and the US Tire Manufacturer's Association are working on regulation and education.[11]

6PPD itself is deadly to rotifers, especially in combination with sodium chloride, though not at the level generally found in the runoff from road salt.[12]

A synthetic route to the 6PPD-quinone has been posted on ChemRxiv.[13]

See also


  1. ^ U.S. Tire Manufacturers Association (July 15, 2021). "Statement of Sarah E. Amick Vice President EHS&S and Senior Counsel U.S. Tire Manufacturers Association". Committee on Natural Resources Subcommittee on Oversight and Investigations United States House of Representatives.
  2. S2CID 10548886
  3. ^ Tian, Zhenyu; Zhao, Haoqi; Peter, Katherine T.; Gonzalez, Melissa; Wetzel, Jill; Wu, Christopher; Hu, Ximin; Prat, Jasmine; Mudrock, Emma; Hettinger, Rachel; Cortina, Allan E.; Biswas, Rajshree Ghosh; Kock, Flávio Vinicius Crizóstomo; Soong, Ronald; Jenne, Amy; Du, Bowen; Hou, Fan; He, Huan; Lundeen, Rachel; Gilbreath, Alicia; Sutton, Rebecca; Scholz, Nathaniel L.; Davis, Jay W.; Dodd, Michael C.; Simpson, Andre; McIntyre, Jenifer K. (3 December 2020), "A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon",
    S2CID 227281491
    , ... existing TWP [tire wear particle] loading, leaching, and toxicity assessments are clearly incomplete. ... Accordingly, the human health effects of such exposures merit evaluation. ... It is unlikely that coho salmon are uniquely sensitive ...
  4. ^ Also an erratum to this paper published in Science vol. 375, No. 6582, 18 Feb 2022 DOI: 10.1126/science.abo5785 reporting the updated toxicity estimates, as referenced below.
  5. ^ "Pollution from car tires is killing off salmon on US west coast, study finds". The Guardian. 3 December 2020.
  6. ^ "Scientists solve mystery of mass coho salmon deaths. The killer? A chemical from car tires". Los Angeles Times. 3 December 2020.
  7. PMID 34347118
  8. ^
    S2CID 247336687{{citation}}: CS1 maint: multiple names: authors list (link
  9. ^ Tian, Zhenyu; Gonzalez, Melissa; Rideout, Craig; Zhao, Hoaqi Nina; Hu, Ximin; Wetzel, Jill; Mudrock, Emma; James, C. Andrew; McIntyre, Jenifer K; Kolodziej, Edward P (11 January 2022), "6PPD-Quinone: Revised Toxicity Assessment and Quantification with a Commercial Standard",
  10. ^ Lena Beck (17 May 2022). "Your car is killing coho salmon". The Counter.
  11. S2CID 247577987
    – via Dynatrait.
  12. .