UN 2698 — Tetrahydrophthalic anhydrides
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2698 At a Glance
UN 2698 (Tetrahydrophthalic anhydrides) is listed as DOT Class 8 Corrosive and is assigned to ERG Guide 156. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
Tetrahydrophthalic anhydrides are corrosive combustible anhydride materials. Isomer and physical form can vary, so responders should confirm the exact product.
Hazard overview: Tetrahydrophthalic anhydrides is corrosive and water-reactive. Moisture contact can release heat and acid fumes, increasing inhalation and contact hazards.
Response guidance: Keep the product dry, isolate the area and avoid direct water application to the material. Use Dry chemical, CO2 or cautious water spray from distance; avoid direct water on bulk product when compatible, and cool nearby containers only from a safe distance.
Firefighter training notes: Train crews to identify Tetrahydrophthalic anhydrides by UN number, placard, ERG guide and SDS before choosing entry, isolation or extinguishment tactics.
Regulatory context: Use UN 2698, ERG 156, SDS, container labels and shipping papers to confirm the exact hazard profile and protective action distances.
Storage & handling: Store in closed, compatible containers away from heat, ignition sources and incompatible materials; keep the area ventilated and protected from damage.
UN 2698 Quick Details
Common Hazards of UN 2698
- Corrosive and/or toxic; contact with liquid, solid, vapor or dust can cause severe injury.
- Water or moisture can generate heat and dense corrosive fumes.
- Fire or heating may produce irritating, toxic or corrosive gases.
- Vapors or fumes may collect in low or poorly ventilated areas.
- Runoff from fire control can be corrosive and environmentally damaging.
- Containers may rupture if heated or contaminated with water.
- Contact with incompatible materials may cause violent reaction.
Chemical Identity & Physical Properties
White to pale yellow crystalline solid or viscous liquid with acrid irritating odor, depending on isomer.
| Also known as | THPATetrahydrophthalic acid anhydride1,2,3,6-Tetrahydrophthalic anhydride3,4,5,6-Tetrahydrophthalic anhydrideHexahydrophthalic anhydride (isomer)HHPA |
| CAS Number | 85-43-8 |
| Appearance | White to pale yellow crystalline solid or viscous liquid (depending on isomer). Acrid, irritating odor. Combustible at room temperature. |
| Flash Point | 153°C (307°F) |
| Boiling Point | 195-200°C (383-392°F) |
| Vapor Density | 5.2 (heavier than air) |
| Water Reactivity | Reacts with water to form acidic corrosive products and heat; large quantities may react vigorously |
Fireground Response Guidance — UN 2698
Extinguishing Media
PPE Requirements
Use SCBA with acid-resistant chemical protective suit, gloves, boots and face protection; avoid any direct contact.
Isolation & Evacuation
First Actions for a UN 2698 Incident
- Call 911 and the emergency response number shown on shipping papers or container documents.
- Keep unauthorized personnel away and establish an initial isolation perimeter.
- Stay upwind, uphill and upstream; avoid low areas where vapors or runoff may collect.
- Avoid breathing vapors, dust, smoke or mist and prevent skin and eye contact.
- Keep water away from the product unless specialist guidance confirms it is safe for cooling or vapor control.
- Do not touch damaged containers or spilled material without appropriate chemical PPE.
- Ventilate confined spaces only when personnel are trained, monitored and properly equipped.
- Use ERG guidance, SDS, shipping papers and air monitoring before committing crews.
📋 Copy & Share Field Card
UN 2698 — Tetrahydrophthalic anhydridesUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.