A reactive waste is a material that is normally unstable and undergoes violent chemical change without detonating, can react violently with water to form potentially explosive mixtures or can generate dangerous or possibly lethal gases. A material that is capable of detonation or explosive reaction is a reactive waste.

Picric acid (2,4,6, trinitrophenol), a potentially explosive compound. It is usually purchased containing 10-15 percent water, in which state it is relatively safe. However, if allowed to dry, it should be treated as a dangerous explosive and Environmental Health and Safety should be notified. List of shock-sensitive compounds includes, among others:

• Acryl and alkyl nitrites
• Alkyl perchlorates
• Azides
• Diazo compounds
• Dry diazonium salts
• peroxides
• Hydroperoxides
• Poly nitro alkyl/aromatic compounds.

Many common laboratory chemicals can form explosive peroxides on exposure to air over time. The compounds on this list should be dated when opened and disposed of in specified periods of time. For example, diisopropyl ether is particularly susceptible to peroxide formation and, if its use is required, it should be completely used or disposed of within three months of opening. If older stocks of isopropyl ether are discovered, Environmental Health and Safety should be notified before handling.

Chemicals that may form peroxides but cannot clearly be placed in the above tables

Perchloric acid is a very strong oxidizing agent, often used for the hot digestion of a variety of materials. Perchloric acid as used in the cold, dilute form in certain biochemical protocols is relatively safe. It can cause violent explosions if misused or when concentrated above the normal commercial strength of 72%. Anhydrous perchloric acid should never be prepared as it is unstable at room temperature and will decompose with a violent explosion. The following rules for the hot use of perchloric acid must be followed at all times:

• Hot perchloric acid work may only be conducted in a rated perchloric acid hood or, under special, well-controlled circumstances, with a high efficiency scrubber.
• A perchloric acid hood must be washed down after every use or once per week, whichever comes first.
• Do not store or use organic materials, such as solvents, in a perchloric acid use hood.
• If a vacuum is needed for perchloric acid work use a water aspirator rather than a mechanical pump. Perchloric acid contact with hydrocarbon based oils or greases in a conventional mechanical vacuum pump may result in an explosion.
• Use the minimum amount of material possible.
• Purchase the smallest quantity available for your needs.
• Store perchloric acid away from all oxidizable materials using secondary containment.
• All containers of perchloric acid in storage must be inspected frequently. Discolored perchloric acid is dangerous and must be disposed of at once.
• Do not use or store perchloric acid on wooden lab furniture or cracker or porous benchtop materials.
• When possible, use alternative techniques not requiring perchloric acid.
• Do not attempt to clean up spills of concentrated perchloric acid yourself as contact with oxidizable materials can cause an immediate explosion. If you spill perchloric acid call 911 and EH&S will respond to clean up the spill.
  

Ether, dioxane and tetrahydrofuran are susceptible to peroxide formation. Once opened, stocks of these chemicals should be used up within six months. After six months they must be tested for peroxide formation. Test strips for determining the amount of peroxides in solvents are available from the Chemistry Department stockroom. If the amount of peroxide is over 80 parts per million, the material should be discarded. If a peroxide bearing solvent is not discarded after six months the peroxide must be destroyed using the appropriate procedures. For assistance call Environmental Health and Safety at 255-8200.