Perfluorononanoic acid

Perfluorononanoic acid

Perfluorononanoic acid
Identifiers
CAS number 375-95-1 YesY
PubChem 67821
EC number 206-801-3
Properties
Molecular formula C9HF17O2
Molar mass 464.08 g/mol
Appearance white crystalline powder
Melting point

59–62 °C[1]

Boiling point

218 °C[2]

Solubility in water 9.5 g/L[3]
Solubility in other solvents polar organic solvents
Acidity (pKa) ~0[4][5]
Hazards
R-phrases R22 R34 R52/53
S-phrases S26 S36/37/39 S45
Main hazards Strong Acid, Causes Burns
Related compounds
Related compounds Trifluoroacetic acid (TFA), Perfluorooctanoic acid (PFOA), Perfluorooctanesulfonic acid (PFOS)
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Perfluorononanoic acid, or PFNA, is a synthetic perfluorinated carboxylic acid and fluorosurfactant that is also an environmental contaminant found in people and wildlife along with PFOS and PFOA.

Chemistry and properties

In acidic form it is a highly reactive strong acid. In its conjugate base form as a salt it is stable and commonly ion paired with ammonium. In the commercial product Surflon S-111 (CAS 72968-3-88) it is the primary compound present by weight. PFNA is used as surfactant for the production of the fluoropolymer polyvinylidene fluoride.[6][7] It is produced mainly in Japan by the oxidation of a linear fluorotelomer olefin mixture containing F(CF2)8CH=CH2. It can also be synthesized by the carboxylation of F(CF2)8I. PFNA can form from the biodegradation of 8:2 fluorotelomer alcohol.[8] Additionally, it is considered a probable degradation product of many other compounds.[9]

PFNA is the largest perfluorinated carboxylic acid surfactant. Fluorocarbon derivatives with terminal carboxylates are only surfactants when they possess five to nine carbons.[10] Fluorosurfactants reduce the surface tension of water down to half of what hydrocarbon surfactants can by concentrating at the liquid-air interface due to the lipophobicity of fluorocarbons.[10][11] PFNA is very stable and is not known to degrade in the environment by oxidative processes because of the strength of the carbon–fluorine bond and the electronegativity of fluorine.

Environmental and health concerns

Like the eight-carbon PFOA, the nine-carbon PFNA is a developmental toxicant and an immune system toxicant.[12] However, longer chain perfluorinated carboxylic acids (PFCAs) are considered more bioaccumulative and toxic.[13] PFNA is an agonist of the nuclear receptors PPARα and PPARγ.[12] In the years between 1999–2000 and 2003–2004, the geometric mean of PFNA increased from 0.5 parts per billion to 1.0 parts per billion in the US population's blood serum.[14] In a cross-sectional study of 2003–2004 US samples, a higher (13.9 milligram per deciliter) total cholesterol level was observed in when the highest quartile was compared to the lowest.[15] Non-HDL cholesterol (or "bad cholesterol") levels were also higher in samples with more PFNA.

In bottlenose dolphins from Delaware Bay, PFNA was the perfluorinated carboxylic acid measured in the highest concentration in blood plasma; it was found in concentrations well over 100 parts per billion.[16] PFNA has been detected in polar bears in concentrations over 400 parts per billion.[17] PFNA was the perfluorinated chemical measured in the highest concentration in Russian Baikal seals.[18] However, PFOS is the perfluorinated compound that dominates in most wildlife biomonitoring samples.[19]

See also

  • Organofluorine compounds

References

External links

  • PDF
  • Centers for Disease Control and Prevention, Polyfluorochemicals fact sheet
  • Perfluorinated substances and their uses in Sweden
  • Perfluoroalkylated substances, Aquatic environmental assessment
  • Chain of Contamination: The Food Link, Perfluorinated Chemicals (PFCs) Incl. PFOS & PFOA