"Street Chemistry" For Emergency Responders - Part 7

The past two "Street Chemistry" columns have focused on basic groups of hydrocarbon-derivative compounds. Rules for naming and identifying the families and determining the hazards have been mostly straightforward. Photo by Robert Burke...


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The past two "Street Chemistry" columns have focused on basic groups of hydrocarbon-derivative compounds. Rules for naming and identifying the families and determining the hazards have been mostly straightforward.

5_98_hazmat1.jpg
Photo by Robert Burke
Vehicle accidents may produce spills of ethylene or propylene glycol, which are used as antifreeze and cooing solutions in engines.

There are, however, other compounds that contain two or more hydrocarbon-derivative families or several different elements attached to the hydrocarbons. For the purposes of "Street Chemistry" let's refer to them as "complex hydrocarbon derivatives." These compounds are not as clear on first glance as to the family they belong to or the hazards that may be associated with them. Even so, you can still apply the information you know about the specific families or elements in the compound based on worst-case scenarios, until the compounds can be looked up in reference materials and the hazards verified.

In the compound methyl ethyl ketone peroxide, for example, there are two hydrocarbon derivative families - ketone and peroxide (organic). Ketones are flammable and narcotic, while peroxides are potentially explosive and oxidizers. By taking precautions for all of the families identified responders would be looking at the worst-case scenario.

Methyl ethyl ketone peroxide is listed in the Condensed Chemical Dictionary as being a "fire risk in contact with organic materials and a strong irritant to skin and tissue." CFR 49 Hazardous Material Table lists it as a "forbidden" commodity in transportation when the active oxygen in the compound is greater than 9%. Methyl ethyl ketone peroxide is listed in the 1996 North American Emergency Response Guide (NAERG96) as an organic peroxide/heat and contamination sensitive and a severe irritant. Manufacturer Safety Data Sheets (MSDS) indicate that the material is stable, will not undergo polymerization and is a combustible liquid.

The point I am making here is if you had taken the worst-case scenario for methyl ethyl ketone peroxide, you would have been in error. However, it is always better to err on the side of safety. Taking precautions for an organic peroxide would have protected you against this compound. Overprotection, yes, but overprotection on the side of safety is better when you don't know the exact hazards of a compound. You may be teased, have "egg on your face" or be embarrassed; however, no one has ever died from any of those things. But if you don't err on the side of safety, when you haven't verified the hazards, you could be seriously injured or die!

5_98_hazmat2.jpg
Photo by Robert Burke
Methyl ethyl ketone peroxide and benzoyl peroxide are Class 5.2 organic peroxide compounds that carry this type of placard in shipments.

Methyl ethyl ketone peroxide (MEKP) is most commonly found as a hardening agent for fiberglass-reinforced plastics. Under the United Nations/Department of Transportation (UN/DOT) classification systems it is a Class 5.2 Organic Peroxide. The UN four-digit identification number is 2550 and Orange Guide 147 from the NAERG96 is used for first responder information. MEKP has a boiling point of 293 degrees Fahrenheit, a flash point of >140 degrees F, is heavier than air and is listed as a combustible liquid class IIIA under the OSHA Flammability Class. Combustion products include carbon monoxide, carbon dioxide and various hydrocarbons.

Benzoyl peroxide is another compound that has the peroxide and ketone derivative families in the structure and formula. It is also listed as a UN/DOT Class 5.2 organic peroxide. The UN identification number is 2085 and Orange Guide 146 is used from the NAERG96. When wet, it is stable; when dry with less than 1% water, it may explode spontaneously. It is also highly toxic by inhalation with a TLV of 5 mg/m3 of air.

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