R-c318

The FDA food-propellant approval was granted decades ago based on chemical inertness and lack of toxicity — R-c318 doesn't react with food, doesn't impart taste, doesn't decompose into harmful products. The environmental impact was not part of the food-safety evaluation. Per-use emissions are tiny (a few grams per food product). Aggregate emissions from food propellant use are negligible compared to industrial PFC uses. The FDA approval remains valid; whether continued use is appropriate given modern climate concerns is a question being raised in some regulatory contexts but no formal restriction is in place as of 2025.

Plasma chemistry. In semiconductor fabrication, RF energy is used to ionize a process gas, creating a plasma containing reactive radicals. R-c318 plasmas generate fluorine and CFₓ radicals that are highly effective at etching silicon, silicon dioxide, and silicon nitride — the primary materials in integrated circuit fabrication. The cyclic structure of R-c318 (vs linear C₄F₁₀) produces a different distribution of plasma products with specific etching characteristics. Substitutes are limited because the plasma chemistry is the property required, not a simple thermal property that other fluorocarbons could provide.

GWP 10,300 per IPCC AR5. Atmospheric lifetime 3,200 years — molecules released today will persist in the atmosphere through approximately the year 5225 (in 2025). This is the second-longest atmospheric lifetime among commercial refrigerants, exceeded only by sulfur hexafluoride (SF₆) at 3,200 years also and tetrafluoromethane (CF₄, R-14) at 50,000 years.

For refrigeration applications, yes — R-c318's refrigeration uses are niche and substitutes exist (HFCs, HFO blends, sometimes hydrocarbons depending on application). For semiconductor manufacturing, substitution is much more difficult — the plasma chemistry of R-c318 in etching processes is engineered-around at the integrated circuit design level; changing the etchant gas would require redesigning IC fabrication processes. The semiconductor industry's response has been emissions abatement (destruction of PFC exhaust before release) rather than substitution.