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6PPD & 6PPD-q in the Environment

April 22nd, 2026

6PPD is a chemical commonly used when manufacturing tires to enhance durability, which transforms into 6PPD-quinone (6PPD-q) when it breaks down. 6PPD-q is known to be toxic to aquatic life and raises concern for its negative impact on the environment and human health.

What is 6PPD and 6PPD-quinone?

6PPD

CAS # 793-24-8
N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine

6PPD Chemical Structure6PPD Chemical Structure

6PPD is a chemical additive used in automotive tires to prevent degradation. As an antioxidant and antiozonant in the phenylamine family, it protects rubber from cracking by reacting with ozone before the ozone can damage the tire material.

As tires wear, 6PPD moves to the surface and reacts with ozone, creating 6PPD-q.

6PPD-quinone

CAS # 2754428-18-5
2-((4-Methylpentan-2-yl)amino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione

6PPD-quinone Chemical Structure6PPD-quinone Chemical Structure

6PPD-quinone (6PPD-q) is released into the environment primarily through tire wear particles. Studies have shown that even very low concentrations of 6PPD-q can be lethal to certain aquatic species.

Environmental Cycle of 6PPD and 6PPD-q

Tire wear particles containing 6PPD transform into 6PPD-q and enter waterways where fish and other aquatic life ingest them. These toxic compounds are known to increase the risk of mortality among aquatic organisms, particularly coho salmon, and is linked to a condition known as urban runoff mortality syndrome. There are potential negative implications on humans who ingest fish containing 6PPD-q.

Infographic showing how 6PPD and 6PPD-Q compounds from tire wear are released and move through the environment.Infographic showing how 6PPD and 6PPD-Q compounds from tire wear are released and move through the environment.

Reference Standards for 6PPD & 6PPD-q Regulations

AccuStandard offers a variety of Certified Reference Materials (CRMs) to support the identification and study of 6PPD, its transformation products such as 6PPD-q, and a range of replacement candidates found in industrial and consumer products. The EPA and other regulatory institutions have published test methods to support the quantification of 6PPD-q, with the goal of monitoring and limiting its presence in the environment. EPA Draft Method 1634 is a draft method used to determine 6PPD-q in surface water using LC-MS/MS.

  1. PLAS-AD-004N
    N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD)
    Neat
  2. NEW! PLAS-AD-004S-CN-0.1X
    N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD)
    100 µg/mL in Acetonitrile
    Single
  3. M-1634
    6PPD-quinone
    100 µg/mL in Acetonitrile
    Single
  4. M-1634-IS
    6PPD-quinone-d5
    100 µg/mL in Acetonitrile
    Single

Alternate Compounds to 6PPD and Other Anti-degradants

Other antioxidant agents are widely used in consumer products to protect rubber from oxidation and prevent brittleness. Many of these compounds exhibit properties similar to 6PPD due to structural similarities. This resemblance also suggests the potential for similar analogous transformation products and comparable toxicity profiles.

For example, 7PPD (CAS No. 3081-01-4), CPPD (CAS No. 101-87-1), DPPD (CAS No. 74-31-7), and IPPD (CAS No. 101-72-4), are among the commonly used alternatives to 6PPD.

  1. PLAS-AD-003N
    N-Isopropyl-N'-phenyl-1,4-phenylenediamine (IPPD)
    Neat
  2. NEW! PLAS-AD-003S-CN-0.1X
    N-Isopropyl-N'-phenyl-1,4-phenylenediamine (IPPD)
    100 µg/mL in Acetonitrile
    Single
  3. PLAS-AX-048N
    N,N'-Diphenyl-1,4-phenylenediamine (DPPD)
    Neat
  4. NEW! PLAS-AX-048S-CN-0.1X
    N,N'-Diphenyl-1,4-phenylenediamine (DPPD)
    100 µg/mL in Acetonitrile
    Single
  5. NEW! PLAS-AX-116S-CN-0.1X
    N-(5-Methyl-2-hexyl)-N'-phenyl-p-phenylenediamine (7PPD)
    100 µg/mL in Acetonitrile
    Single
  6. NEW! PLAS-AX-118S-CN-0.1X
    N-cyclohexyl-N′-phenyl-p-phenylenediamine (CPPD)
    100 µg/mL in Acetonitrile
    Single

Other 6PPD Metabolites

While 6PPD-q is one of the most well-known metabolites, other 6PPD breakdown products have also been studied for their potential toxicity and environmental impact. It is well established that 6PPD can undergo environmental transformation to form several metabolites, some of which may exhibit greater toxicity than the parent compound.

Examples include, 4-hydroxydiphenylamine (CAS No. 122-37-2), 4-Nitrosodiphenylamine (CAS No. 156-10-5), 1,3-dimethylbutylamine (CAS No. 108-09-8), and p-Benzoquinone Standard (CAS No. 106-51-4).

  1. NEW! M-1634-MET-01
    4-Hydroxydiphenylamine
    100 µg/mL in Acetonitrile
    Single
  2. NEW! M-1634-MET-02
    4-Nitrosodiphenylamine
    100 µg/mL in Acetonitrile
    Single
  3. NEW! M-1634-MET-03
    1,3-Dimethylbutylamine
    100 µg/mL in Acetonitrile
    Single
  4. NEW! M-1634-MET-04
    p-Benzoquinone
    100 µg/mL in Acetonitrile
    Single

Additionally, AccuStandard has uniquely synthesized an extended list of 6PPD metabolites to help researchers better understand the environmental impacts and breakdown pathways of this widely used anti-degradant. Contact our Technical Service department if interested in any of these compounds.

Other 6PPD MetabolitesOther 6PPD Metabolites

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