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Microsoft word - 4. reactive and explosive materials.doc
Rubin’s group laboratory operating procedure series
4. Reactive and Explosive Materials
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2. Definitions http://www.ehs.berkeley.edu/pubs/guidelines/pecguidelines.html
The purpose of this standard operating procedure is to provide guidelines
for the safe handling of reactive and explosive materials. SPECIFIC SOPs ARE REQUIRED FOR INDIVIDUAL EXPLOSIVE OR REACTIVE MATERIALS. Consult the MSDS for specific information about a particular reactive or explosive material. Check the appendices at the end of this guide to identify potentially explosive compounds.
Explosive materials are chemical compounds or mechanical mixtures that, when subjected to heat, impact, friction, detonation, or other suitable initiation, undergoes rapid chemical change. Large volumes of highly heated gases are evolved that exert pressure on the surrounding medium. The term applies to materials that either detonate or deflagrate. Heat, light, mechanical shock, and certain catalysts initiate explosive reactions. For a comprehensive list of potentially explosive compounds, visit the website:
The list is included in the Appendices. View this list VERY CAREFULLY.
The following are some commonly used chemicals that can become an explosion hazard under certain conditions:
Organic chemicals that form PEROXIDES
through exposure to air or light (see
Appendix 2 - Peroxide Forming Chemicals)
Organic azides and the azide salts of heavy metals.
Hydrated picric acid that becomes dry or becomes contaminated with metals that
Sodium amide that reacts with air or moisture to form superoxides, as evidenced by
Certain alkyl nitrates (e.g., butyl nitrate or propyl nitrate) that become contaminated
Certain normally-stable perchlorates (e.g., pyridium perchlorate or
tetraethylammonium perchlorate) that become unstable at elevated temperatures
Note: Most explosions occur while purifying or distilling mixtures. Therefore, use extreme
caution before concentrating or purifying any mixture that may contain an explosive
chemical (e.g., a peroxide forming chemical or perchlorate).
There is an additional group of chemicals that should be considered although they are not necessarily heat-, light-, friction-, or shock-sensitive. These chemicals give off gaseous degradation by-products that may cause over-pressurization of the container and explode. They can degrade over time and should be incorporated into a safety and handling system that will prevent them from becoming explosive hazards (see Appendix 3).
Pyrophoric materials ignite spontaneously when exposed to air at a temperature of 54.4 °C (130 °F) or below. Reaction by-products are toxic fumes or gases and liberation of heat. Many pyrophoric materials are water reactive as well. Examples include white phosphorus, many finely divided metals, some metal hydrides, certain silanes and certain alkyl lithiums, for example, t
-butyl lithium. The reader is directed to the specific SOP for using pyrophoric materials.
2.3. Reactive (unstable)
Reactive (unstable) materials are chemicals that will vigorously polymerize, decompose, condense, or will become self-reactive under conditions of shocks, pressure or temperature.
2.4. Water reactive
Water reactive materials react violently with water to produce toxic, corrosive, or flammable gases and the liberation of heat. Some examples are listed.
Non-metal Halides (e.g.
BCl3, BF3, PCl3, SiCl4, S2Cl2)
Inorganic acid halides (e.g.
POCl3, SOCl2, SO2Cl2)
Anhydrous metal halides (e.g.
AlCl3, TiCl4, ZrCl4, SnCl4)
Organic acid halides and anhydrides of low molecular weight
Metal and non-metal hydrides (boranes, LiAlH )
3. PERSONAL PROTECTIVE EQUIPMENT (PPE)
Chemical splash GOGGLES for eye protection in combination with a FULL-LENGTH FACE SHIELD to fully protect the face and throat.
Heavy, non-reactive GLOVES should be worn when handling reactive compounds or in the event it is necessary to reach behind a shielded area while a hazardous experiment is in progress. Check glove manufacturer for recommendations on a suitable glove for the specific chemical.
Close-toed shoes (non-fabric) with non-slip soles.
If a respirator is needed, then user must use their personal respirator fitted to their face.
4. ENGINEERING AND VENTILATION CONTROLS
All procedures involving reactive materials must be conducted in a fume hood to protect against runaway reactions and hazardous exposure.
5. SPECIAL HANDLING PROCEDURES
These procedures are general. For specific
compounds and procedures, consult the specific SOP.
If you are using reactive reagents, inform your lab mates. They need to be aware of what you
are doing, what chemicals you are using, and they will need to know how to deal with an
Conduct procedures in a fume hood.
Use a BLAST SHIELD in combination with the hood sash to protect personnel and equipment
from injury or damage from a possible explosion or fire. Consider using the sliding screen also.
Minimize the quantity of reactive (unstable) materials used and stored in the work area.
Label incoming containers with the date of receipt. Do not use reactive materials past their
Exercise due care when handling peroxide formers. Visually inspect bottle cap and threads of
container (without handling) for presence of organic peroxide crystals. If present, evacuate area and
deny entry. Contact EH&S. If container appears free of encrustation, test for peroxides using the
methods below. If peroxides are detected, contact EH&S for disposal. NOTE: Test should be
Add 1 to 3 mL of the liquid to be tested to an equal amount of acetic acid, add a few drops of
5% aqueous potassium iodide solution, and shake. The appearance of a yellow to brown color indicates the presence of peroxides. Alternatively, addition of 1 mL of a freshly prepared 10% solution of potassium iodide to 10 mL of an organic liquid in a 25-mL glass cylinder should produce a yellow color if peroxides are present.
Add 0.5 mL of the liquid to be tested to a mixture of 1 mL of 10% aqueous potassium iodide
solution and 0.5 mL of dilute hydrochloric acid to which has been added a few drops of starch solution just prior to the test. The appearance of a blue or blue-black color within a minute indicates the presence of peroxides.
Use commercially available peroxide test strips.
6. LABELLING REQUIREMENTS
Label storage cabinets or areas with appropriate descriptor: WATER REACTIVE,
PYROPHORIC, OR EXPLOSIVE.
Label all incoming containers with the date of receipt.
7. STORAGE REQUIREMENTS
Minimize the amount of reactive materials used and stored.
Store peroxide formers in tightly sealed metal containers in areas away from oxidizers.
Do not return unused material to the original container.
8. SPILL AND ACCIDENT PROCEDURES
See chemical spill clean-up SOP and UCLA laboratory safety manual (Chapter 10).
9. WASTE DISPOSAL
Handle all waste following UCLA guidelines (laboratory safety manual Chapter 11).
10. APPENDIX 1: Explosive and Potentially Explosive Chemical Families
Acetylene or acetylide compounds:
Diazonium carboxylates, perchlorates, salts, sulfates,
tetrahaloborates, and, triiodides
Bis(1,2-diaminoethane) diaquacobalt (III) perchlorate Hydroxooxodiperoxochromate salts
Metal Azide Halides
Bis(cyclopentadienyl)tungsten diazide oxide
Bis (1-chloroethylthallium chloride) oxide o-Trifluoromethyl
Potassium cyclohexanehexone 1,3,5-trioximate
Oxosalts of Nitrogenous Bases
Many transition metal peroxides are dangerously
2-Sodium tetraperoxomolybdate trans-2-Butene
Perchlorate Salts of Nitrogenous Bases
Nitrogenous Base Nitrite Salts
Potassium tetraperoxomolybdate Dicyclopropyldiazomethane
Tetramethylammonium pentaperoxodichromate Prismane
Silver and mercury salts of 5-nitrotetrazole
O-O-tert-Butyl isopropyl monoperoxycarbonate
Poly(dimercuryimmonium permanganate) Disilver
APPENDIX 2: COMMON PEROXIDE-FORMING COMPOUNDS
List A–Chemicals that may form explosive levels of peroxides without concentration by evaporation or distillation
materials are particularly dangerous because they can be hazardous even if never opened.
List B–Chemicals that form explosive levels of peroxides on concentration.
They typically accumulate hazardous levels of
peroxides only when evaporated, distilled or otherwise treated to concentrate the peroxides (e.g. deactivation or removal of
peroxide inhibitors). Therefore, they have the potential of becoming far more hazardous after they are opened.
2-Cyclohexen-1-ol 4-Hepitanol 1-Phenylethanol
Decahydronaphthalene Methylacetylene 2-Propanol
List C–Chemicals that may autopolymerize as a result of peroxide accumulation.
These chemicals have been associated with
hazardous polymerization reactions that are initiated by peroxides which have accumulated in solution. These materials are
typically stored with polymerization inhibitors to prevent these dangerous reactions.
List D: Other peroxidizable chemicals which cannot be placed into the other categories but nevertheless require handling
2-Chlorobutadiene 1,2-Epoxy-3-phenoxypropane 3-Methoxyethyl acetate
p-Ethoxyacetophenone 2-Methoxyethyl vinyl ether
o,p-Ethoxyphenyl isocyanate Oxybis(2-ethyl acetate)
Bis(2-ethoxyethyl) adipate 1,2-Dibenzyloxyethane Ethyl-b-ethoxypropionate
Bis(2-methoxyethyl) ether 1,2-Dichloroethyl ethyl ether
Isobutyl vinyl ether 1,3,3-Trimethoxypropene
Buten-3-yne 3,3-Dimethoxypropene 1,5-p-Methadiene
APPENDIX 3. CHEMICALS THAT MAY EXPLODE DUE TO OVER-PRESSURIZED
Aluminum lithium hydride
Lithium aluminum hydride
Silicon tetrachloride Sodium borohydride Sodium dithionite Sodium hydride Sodium hydrosulphite Sodium hypochlorite Sodium peroxide Sodium persulphate Thionyl chlroide Urea peroxide Zinc
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