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The United States Environmental Protection Agency (“EPA”) published a November 28th Federal Register Notice that revises the regulatory definition of volatile organic compounds (“VOCs”) under the Clean Air Act. See 83 Fed. Reg. 61227.

The final rule exempts cis-1,1,1,4,4,4-hexafluorobut-2-ene.

HFO-1336mzz-Z is added to the list of compounds excluded from the regulatory definition of VOC. The rationale for this action is EPA’s contention that the compound makes a negligible contribution to tropospheric ozone formation.

EPA states that DuPont Chemicals & Fluoroproducts had submitted a petition to the agency on February 14, 2014, asking that cis-1,1,1,4,4,4-hexafluorobut-2-ene be exempted from the regulatory definition of VOC. The company argued that HFO-1336mzz-Z possesses low reactivity relative to ethane. The petitioner is also stated to have noted that:

. . . HFO-1336mzz-Z may be used in a variety of applications as a replacement for foam expansion or blowing agents with higher global warming potential (GWP) (≤700 GWP) for use in polyurethane rigid insulating foams, among others. It is also a new developmental refrigerant as a potential working fluid for Organic Rankine Cycles (ORC).

The preamble to the final rule addresses:

• EPA’s VOC Exemption Policy
• The Petition
• EPA’s Assessment of the Petition
  • Contribution to Tropospheric Ozone Formation
  • Potential Impacts on Other Environmental Endpoints
    • Contribution to Tropospheric Ozone Depletion
    • The Significant New Alternatives Policy Program Acceptability Findings
    • Toxicity
    • Contribution to Climate Change
• Response to Comments and Conclusion

A copy of the Federal Register Notice can be found here.