''N''-Isopropyl-''N''′-phenyl-1,4-phenylenediamine (often abbreviated IPPD) is an
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
commonly used as an
antiozonant
An antiozonant, also known as anti-ozonant, is an organic compound that prevents or retards damage caused by ozone. The most important antiozonants are those which prevent degradation of elastomers like rubber. A number of research projects stud ...
in rubbers. Like other
p-phenylenediamine-based antiozonants it works by virtue of its low
ionization energy
In physics and chemistry, ionization energy (IE) is the minimum energy required to remove the most loosely bound electron of an isolated gaseous atom, Ion, positive ion, or molecule. The first ionization energy is quantitatively expressed as
: ...
, which allows it to react with
ozone
Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...
faster than ozone will react with rubber.
This reaction converts it to the corresponding
aminoxyl radical (R
2N–O•), with the ozone being converted to a hydroperoxyl radical (HOO•),
these species can then be scavenged by other antioxidant
polymer stabilizers Polymer stabilizers (British English: polymer stabilisers) are chemical additives which may be added to polymeric materials to inhibit or retard their degradation. Mainly they protect plastic and rubber products against heat, oxidation, and UV light ...
.
IPPD is prone to process called
blooming
Bloom or blooming may refer to:
Science and technology Biology
* Bloom, one or more flowers on a flowering plant
* Algal bloom, a rapid increase or accumulation in the population of algae in an aquatic system
* Jellyfish bloom, a collective n ...
, where it migrates to the surface of the rubber. This can be beneficial to the tire, as ozone attacks the tire surface and blooming therefore moves the antiozonant to where it is most needed, however this also increases the
leaching of IPPD into the environment. Many tire producers have moved to using
6PPD
6PPD is an organic chemical widely used as stabilising additive (or antidegradant) in rubbers, such as NR, SBR and BR; all of which are common in vehicle tires. Although it is an effective antioxidant it is primarily used because of its excel ...
instead, as this migrates more slowly. Oxidation of IPPD converts the central phenylenediamine ring into a
quinone
The quinones are a class of organic compounds that are formally "derived from aromatic compounds benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= groups into –C(=O)– groups with ...
.
Safety
IPPD is a human
allergen
An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response.
In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivi ...
. It is the compound responsible for coining the term "Volkswagen Dermatitis". There is some preliminary evidence for it being harmful to fish.
See also
*
''N'',''N''′-Di-2-butyl-1,4-phenylenediamine - a phenylenediamine based antioxidant used as a fuel additive
References
{{DEFAULTSORT:Isopropyl-N'-phenyl-1,4-phenylenediamine, N-
Antioxidants
Diamines
Plastics additives
Isopropylamino compounds