3.2.1 General Information
Highly reactive chemicals include those which are inherently unstable and susceptible to rapid decomposition as well as chemicals which, under specific conditions, can react alone or with other substances in a violent uncontrolled manner, liberating heat, toxic gases or leading to an explosion. Reaction rates almost always increase dramatically as the temperature increases. Therefore, if heat evolved from a reaction is not dissipated, the reaction can accelerate out of control and possibly result in injuries or costly accidents.
Air, light, heat, mechanical shock (when struck, vibrated or otherwise agitated), water and certain catalysts can cause decomposition of some highly reactive chemicals and initiate an explosive reaction. Hydrogen and chlorine react explosively in the presence of light. Alkali metals such as sodium, potassium and lithium, react violently with water liberating hydrogen gas. Examples of shock sensitive materials include acetylides, azides, organic nitrates, nitro compounds and many peroxides.
Organic peroxides are a special class of compounds that have unusual stability problems making them among the most hazardous substances normally handled in the laboratories. As a class, organic peroxides are low powered explosives. Organic peroxides are extremely sensitive to light, heat, shock, sparks and other forms of accidental ignition; as well as to strong oxidizing and reducing materials. All organic peroxides are highly flammable.
Peroxide former’s can form peroxides during storage and especially after exposure to the air (once opened) and light. Peroxide forming substances include:
- Aldehydes
- Ethers (especially cyclic ether such as THF)
- Compounds containing benzylic hydrogen atoms
- Compounds containing the allylic structure (including most alkenes)
- Vinyl and vinylidine compounds
- Some alcohols (such as Isopropyl Alcohol)
Examples of shock sensitive chemicals, high energy oxidizers and substances which can form explosive peroxides are listed at the end of this section.
3.2.2 – Special Handling Procedures
Before working with a highly reactive material or high-energy oxidizer, review available reference literature to obtain specific safety information. The proposed reactions should be discussed with your supervisor. Always minimize the amount of material involved in the experiment; the smallest amount sufficient to achieve the desired result should be used. Scale- ups should be handled with great care, giving consideration to the reaction vessel size and cooling, heating, stirring and equilibration rates.
Excessive amounts of highly reactive compounds should not be purchased, synthesized, or stored in the laboratories. The key to safely handling reactive chemicals is to keep them isolated from the substances that initiate their violent reactions. Unused peroxides should not be returned to the original container.
Do not work alone. All operations where highly reactive and explosive chemicals are used should be performed during the normal work day or when other employees are available either in the same laboratory or in the immediate area.
Perform all manipulations of highly reactive or high energy oxidizers in a chemical fume hood. (Some factors to be considered in judging the adequacy of the hood include its size in relation to the reaction and required equipment, the ability to fully close the sash, and the composition of the sash.)
Make sure that the reaction equipment is properly secured. Reaction vessels should be supported from beneath with tripods or lab jacks. Use shields or guards which are clamped or secured.
If possible use remote controls for controlling the reaction (including cooling, heating and stirring controls). These should be located either outside the hood or at least outside the shield.
Handle shock sensitive substances gently. Avoid friction, grinding and all forms of impact. Glass containers that have screw-cap lids or glass stoppers should not be used. Polyethylene bottles that have screw-cap lids may be used.
Handle water-sensitive compounds away from water sources.
Light-sensitive chemicals should be used in light-tight containers. Handle highly reactive chemicals away from the direct light, open flames and other sources of heat. Oxidizing agents should only be heated with fiberglass heating mantles or sand baths.
High energy oxidizers, such as perchloric acid, should only be handled in a wash down hood if the oxidizer will volatilize and potentially condense in the ventilation system. Inorganic oxidizers such as perchloric acid can react violently with most organic materials.
When working with highly reactive compounds and high-energy oxidizers always wear the following personal protection equipment:
- Lab coats
- Gloves
- Protective glasses/goggle.
- During the reaction, a face shield long enough to give throat protection should be worn.
Labels on peroxide forming substances should contain the date the container was received, first opened and the initials of the person who first opened the container. They should be checked for the presence of peroxides before using and quarterly while in storage (peroxide test strips are available). If peroxides are found, the materials should be decontaminated, if possible, or disposed of. The results of any testing should be placed on the container label. Never distill substances contaminated with peroxides. Peroxide forming substances that have been opened for more than one year should be discarded. Never use a metal spatula with peroxides. Contamination by metals can lead to explosive decompositions.
Store highly reactive chemicals and high-energy oxidizers in closed cabinets segregated from the materials with which they react and, if possible, in secondary containers. You can also store them in the cabinet under a hood. Do not store these substances above eye level or on open shelves.
Store peroxides and peroxide forming compounds at the lowest possible temperature. If you use a refrigerator make sure it is appropriately designed for the storage of flammable substances. Store light-sensitive compounds in the light-tight containers. Store water-sensitive compounds away from water sources.
Shock sensitive materials should be discarded after one year if in a sealed container and within six months of opening unless an inhibitor was added by the manufacturer.
3.2.3 – List of Shock Sensitive Chemicals
Shock sensitive refers to the susceptibility of the chemical to rapidly decompose or explode when struck, vibrated or otherwise agitated. The following are examples of materials, which can be shock sensitive:
- Acetylides of heavy metals
- Aluminum ophrite explosive
- Amatol
- Ammonal
- Ammonium nitrate
- Ammonium perchlorate
- Ammonium picrate
- Ammonium salt lattice
- Butyl tetryl
- Calcium nitrate
- Copper acetylide
- Cyanuric triazide
- Cyclotrimethylenetrinitramine
- Dinitroethyleneurea
- Dinitroglycerine
- Dinitrophenol
- Dinitrophenolates
- Dinitrophenyl hydrazine
- Dinitrotoluene
- Dipicryl sulfone
- Dipicrylamine
- Erythritol tetranitrate
- Fulminate of mercury
- Fulminate of silver
- Fulminating gold
- Fulminating mercury
- Fulminating platinum
- Fulminating silver
- Gelatinized nitrocellulose
- Germane
- Guanyl nitrosamino guanyltetrazene
- Guanyl nitrosaminoguanylidene hydrazine
- Heavy metal azides
- Hexanite
- Hexanitrodiphenylamine
- Hexanitrostilbene
- Hexogen
- Hydrazinium nitrate
- Hyrazoic acid
- Lead azide
- Lead mannite
- Lead mononitroresorcinate
- Lead picrate
- Lead salts
- Lead styphnate
- Magnesium ophorite
- Mannitol hexanitrate
- Mercury oxalate
- Mercury tartrate
- Mononitrotoluene
- Nitrated carbohydrate
- Nitrated glucoside
- Nitrated polyhydric alcohol
- Nitrogen trichloride
- Nitrogen triiodide
- Nitroglycerin
- Nitroglycide
- Nitroglycol
- Nitroguanidine
- Nitronium perchlorate
- Nitroparaffins
- Nitrourea
- Organic amine nitrates
- Organic nitramines
- Organic peroxides
- Picramic acid
- Picramide
- Picratol
- Picric acid
- Picryl chloride
- Picryl fluoride
- Polynitroaliphatic compounds
- Potassium nitroaminotetrazole
- Silver acetylide
- Silver azide
- Silver styphnate
- Silver tetrazene
- Sodatol
- Sodium amatol
- Sodium dinitro-orthocresolate
- Sodium nitrate-potassium
- Sodium picramate
- Styphnic acid
- Tetranitrocarbazole
- Tetrazene
- Tetrytol
- Trimethylolethane
- Trimonite
- Trinitroanisole
- Trinitrobenzene
- Trinitrobenzoic acid
- Trinitrocresol
- Trinitronaphtalene
- Urea nitrate
3.2.4 – List of High Energy Oxidizers
The following are examples of materials, which are powerful oxidizing reagents:
- Ammonium Perchlorate
- Ammonium Permaganate
- Barium Peroxide
- Bromine
- Calcium Chlorate
- Calcium hypochlorite
- Chlorine Trifluoride
- Chromic Acid
- Chromium Anhydride
- Dibenzoyl Peroxide
- Fluorine
- Hydrogen Peroxide
- Magnesium Perchlorate
- Nitric Acid
- Nitrogen Peroxide
- Perchloric Acid
- Potassium Bromate
- Potassium Chlorate
- Potassium Perchlorate
- Potassium Peroxide
- Propyl Nitrate
- Sodium Chlorate
- Sodium Perchlorate
- Sodium Peroxide
3.2.5 – Peroxidizable Chemicals
Do you have any of the chemicals listed in Section 3.2.6 in your lab? Are you aware of the storage and handling characteristics of these materials that can create hazardous situations?
Answers to these questions are probably yes. Wesleyan University has been fortunate to have no reported negative experiences with shock or heat sensitive materials. With additional knowledge and attention to detail, we should extend this record indefinitely. Peroxidizable compounds tend to absorb and react with oxygen from the air to form unstable peroxides. These may detonate with extreme violence when they become concentrated by evaporation or distillation; when combined with other compounds that give a detonatable mixture: or when disturbed by unusual heat, shock or friction.
Peroxides formed in compounds by auto-oxidation have caused many laboratory accidents, including unexpected explosions of the residue of solvents after distillation. They also have caused a number of hazardous disposal operations. Reported accidents at other universities include:
- An empty 250-cc bottle which had held ethyl ether exploded when the ground glass stopper was replaced.
- Another explosion cost a graduate student the total sight of one eye and most of the sight of the other.
- A third explosion killed a researcher when he attempted to unscrew the cap from an old bottle of isopropyl ether.
The manufacturer packages many peroxidizable chemicals with an inhibitor such as BHT or hydroquinone. If the manufacturer has replaced the headspace of the container with an inert gas such as nitrogen, an unopened bottle or can of material should remain stable. An opened and partially used container provides more headspace and oxygen to enhance the oxidation process. You can find more information about how to order, store and dispose of shock or heat sensitive materials from Pipitone, David A., Safe Storage of Laboratory Chemicals; John Wiley & Sons; New York, 1984 and Furr, A. Keith, CRC Handbook of Laboratory Safety, 3rd Ed; CRC Press: Boca Raton, 1990.
For more information about specific compounds, refer to the SDS available from the chemical manufacturer.
Users of peroxide forming reagents will label any container with the date the container was opened. Once the container has reached the end of its shelf life as indicated below, the container will be disposed of as hazardous waste. If a part-full container is found to be not labeled with a “date opened” date, then the date received (as noted in the CEMS Chemical Inventory Program) will be considered as the date opened. Peroxide test strips will be available upon request through the Sciences stockroom (Hall-Atwater room 054).
Reagent chemicals have been categorized into four classes as described below:
- Class A – These are chemicals that can form explosive levels of peroxides without being concentrated by evaporation. Once opened, these chemicals should only be stored on site for six months. Once six months has passed, these expired chemicals will be disposed of as hazardous waste.
- Class B – These chemicals can form explosive levels of peroxides when concentrated by evaporation. Class B chemicals include aldehydes, ethers, and compounds containing benzilic hydrogens and hydroxyls. Once opened, these chemicals should only be stored on site for one year. Once one year has passed, these expired chemicals will be disposed of as hazardous waste.
- Class C – These chemicals may autopolymerize as a result of peroxide accumulation. Class C chemicals include compounds containing the allylic structure, vinyl and vinylidene compounds. Once opened, these chemicals should only be stored on site for two years. Once two years has passed, these expired chemicals will be disposed of as hazardous waste.
- Class D – These chemicals only rarely form peroxides with long-term storage and exposure to air and light. Class D compounds include primary and secondary alcohols, ketones, ureas, organic amides and lactams. Containers of these chemicals will be labeled with the date opened and any suspect containers tested for the formation of peroxides. A container of Class D reagents will be considered suspect if any discoloration, cloudiness, changes in viscosity, excessive age or other concern is noted. If any peroxide formation is detected, these contaminated chemicals will be disposed of as hazardous waste.
3.2.6 – List of Peroxidizable Compounds
Class A Peroxidizable (six months) | CAS # |
| divinyl ether | 109-93-3 |
| divinylacetylene | 821-08-9 |
| isopropyl ether | 108-20-3 |
| potassium metal | 7440-09-7 |
| sodium amide | 7782-92-5 |
| vinylidene chloride | vinylidene chloride |
Class B Peroxidizable (one year) | CAS # |
| acetal | 98201-60-6 |
| cumene | 98-82-8 |
| cyclohexene | 110-83-8 |
| diacetylene (cyclooxyene) | 460-12-8 |
| dicyclopentadiene | 77-73-6 |
| diethyl ether | 60-29-7 |
| diethylene glycol dimethyl ether (diglyme) | 111-96-6 |
| dioxanes | 123-91-1 and others |
| ethylene glycol dimethyl ether (glyme) | 70992-86-8 |
| furan | 110-00-9 |
| methyl isobutyl ketone | 108-10-1 |
| methylacetylene | 74-99-7 |
| methylcyclopentane | 96-37-7 |
| tetrahydrofuran | 109-99-9 |
| tetrahydronaphthalene | 68412-24-8 |
Class C Peroxidizable (two years) | CAS # |
| acrylic acid | 79-10-7 |
| acrylonitrile | 107-13-1 |
| butadiene | 106-99-0 |
| chlorobutadiene (chloroprene) | 126-99-8 |
| chlorotrifluoroethylene | 79-38-9 |
| methyl methacrylate | 80-62-6 |
| styrene | 100-42-5 |
| tetrafluoroethylene | 116-14-3 |
| vinyl acetate | 108-05-4 |
| vinyl acetylene | 689-97-4 |
| vinyl chloride | 75-01-4 |
| vinyl pyridine | 100-43-6 |
Class D Peroxidizable (date and test)
- primary and secondary alcohols (such as Isopropyl Alcohol)
- ketones, ureas, organic amides and lactams