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Handling Picric Acid

See requirements for UC San Diego researchers working with picric acid.

Picric acid (C6H2(NO2)3OH), also known as trinitrophenol, is primarily used as a chemical reagent and as a booster to detonate other, less sensitive explosives, such as TNT (trinitrotoluene). Picric acid has also been used as an antiseptic, a yellow dye, and in the synthesis of a powerful insecticide.

Requirement for researchers

UC San Diego researchers working with strong oxidizers/potentially explosive materials (PEMs) such as picric acid must complete a hazard control plan (HCP) obtained through the Chemical Hazard Use Application (CHUA). This HCP must be preapproved by the principal investigator prior to beginning any work with this material. Information on this Blink page is supplementary and is not intended to replace the approved HCP.

Never work alone when working with hazardous chemicals.

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Obtain approval before beginning work.

Get approval from your principal investigator before beginning a project involving picric acid.

Evaluate the hazards before beginning work.

Picric acid's explosive nature makes it one of the most hazardous substances found in the laboratory.

  • Consult safety resources available at Safety Data Sheet (SDS) Sources.
  • Physical characteristics:
    • Highly sensitive to heat, shock, or friction
    • A derivative of phenol and is highly reactive to heat, flame, shock, or friction
    • Classified as a:
      • Flammable solid when wetted with more than 30% water
      • High explosive with less than 30% water (wetted product is considerably less shock sensitive than the dry acid)
    • Never allow picric acid to dry out — particularly on metal or concrete surfaces.
  • Health hazards:
    • Toxic by all routes of entry (i.e., inhalation, ingestion, dermal)
    • Produces toxic products on decomposition
    • Skin irritant and allergen
  • Reactivity:
    • Picric acid is highly reactive with a wide variety of materials (e.g., copper, zinc, lead, salts, plaster, concrete, ammonia, etc.) and extremely susceptible to the formation of picrate salts.
    • Picrate salts are formed by the reaction of picric acid with any of the following: metals, metal salts, bases, ammonia, and concrete.
    • Many of these salts are even more reactive and shock sensitive than the acid itself.
    • Metal picrates are particularly sensitive and can be formed with metals such as copper, nickel, lead, iron, and zinc.
    • Calcium picrate is formed by the reaction of picric acid with concrete.
  • Bottles of picric acid left on a laboratory shelf over a period of years are particularly dangerous for 2 reasons. Consider either of these situations extremely serious:
    1. The acid, which usually exists as a wetted paste, may dry out and cause the formation of shock-sensitive acid crystals.
    2. Introduction of impurities (e.g., via spatulas, degrading metal caps, etc.) into bottles that have been previously opened and are no longer airtight can cause formation of picrate salts inside the bottle or within the threads of the lid.
  • If possible, use a less dangerous product that can perform the same task.

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Notice: Disposal of hazardous waste using sinks, intentional evaporation, or as regular trash is against the law. Campus laboratories must abide by strict state and federal waste disposal requirements. You may be held liable for violations of applicable laws.