tert-Butyl Acetate

tert-Butyl acetate (CAS 540-88-5) is an ester solvent used extensively in industrial and DIY coating formulations. It is classified as a Flammable Liquid Category 2 (H225 — flash point approximately 9°C / 48°F), making it one of the more hazardous solvents from a fire-safety standpoint compared to IPA (Flam Liq Cat 2 also) or ethanol (Flam Liq Cat 2). At 40–55% concentration in a coating mixture it drives H335 (respiratory irritation) at the mixture level. Notably, tert-butyl acetate is exempt from federal EPA VOC classification (negligible photochemical reactivity per 40 CFR 51.100), but it is NOT VOC-exempt under California's Cal ARB rules. Products that use it as the primary carrier will report 0% VOC under EPA method while reporting up to ~44% VOC under Cal ARB — a significant regulatory divergence that manufacturers must disclose separately on SDS §15. No Prop 65 listing. Biodegradable by standard OECD 301 protocols. Aquatic toxicity data from SDS show LC50 240 mg/L (fish, 96h) and EC50 410 mg/L (invertebrates, 24h) — well above typical concern thresholds for acute aquatic toxicity; classified as non-hazardous to aquatic life at normal use concentrations.