Freon is word you may recognize as being an important chemical in the refrigeration and air-conditioning industries. Despite its potential for ozone depletion, it remains in use. In fact, every house I've ever been in with air conditioning has used Freon. More on that in a second.
What's In A Name?:
At this point, I should clarify that Freon is a trade name used by Du Pont to describe a class of chemicals known as haloalkanes. Your know that Tylenol is simply the trade name of one company's acetaminophen, for example. So what's a haloalkane. Well, let's start with the last part of the word.
An alkane is any simple organic molecule that is primarily comprised of carbons attached to each other by single bonds. A double bonded carbon in the molecule would make it an alkene. All alkane carry the -ane suffix, just all alkenes carry the -ene suffix. So we have butane and propane pictured below:
The "halo-" simply means anything from the Halogen group on the periodic table, Group 17 (or on some older tables, Group 7A or Group 7). They are: fluorine, F; chlorine, Cl; bromine, Br; iodine, I; and astatine, At. Each of these has a valence of one, meaning they can have one single bond at a time. Now look back up at the alkanes, you'll notice that hydrogen can only bond once. Replace any or all of the hydrogens with chlorine atoms, for example, and you have yourself a simple haloalkane.When you add fluorine to this molecule, it becomes a chlorofluorocarbon, which is still a haloalkane (remember fluorine is a halogen too.) Then you get the handy acronym we are all familiar with:CFC.
The Freon that caused problems on the Russian sub was probably from a class of fire retardants called halons. Halons can kill you at high enough concentrations, and a submarine is a bad place to be if you need to escape toxic gases. UPDATE: The BBC has reported it was a case of asphyxiation, as opposed to direct toxic effect. I suspected this might be the case, as has a commenter, but that's not the way it was reported.
Image from Wikipedia
EEEK! This Stuff Is In My Air Conditioning. PANIC! PANIC! PANIC!:
Freon is also in you refrigerator, but it's not time to panic. First of all, like I said, Freon is a trade name that describes many different chemicals in the same class. The Freon in your home is non-toxic, and that's a major selling point. Before Freon, the stuff we used as refrigerants were toxic. This included things like ammonia, sulfur dioxide, and methyl chloride. A refrigerator leak could be downright dangerous.
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However, as Baum pointed out in the comments below, chances are your newer AC and fridge are not using CFCs, but HFCs or another compound. I've personally been using older stuff, so I forget to mention that the new stuff getting churned out of factories is CFC free, except for Russian products. They still use it in spray cans. Other countries may also be putting CFCs where they don't belong. See below.
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So it's not time to throw out your fridge unless you want to save the ozone, which coincidentally is also technically toxic. Actually, CFCs are technically banned globally. So why do you still see them?
"Psst! you wanna buy some Freon?" The Illicit Trade in CFCs:
News that sounds like a joke: The illicit trade in CFCs is second to cocaine as an illegal import. At least according to Joe Schwarcz, chemistry professor at McGill University. The Montreal Protocol of 1987 allows for stockpiled and recycled CFCs to be used in North America. Older refrigerators and AC units still run on CFCs and must be periodically maintained with this amount. However, countries like Mexico and China are permitted to produce until 2010, and import their wares with false recycled certificates. According to Schwarcz, the Russian Mafia is also making a racket of of this.
I'm waiting to see what will happen in 2010, when many of these sources are no longer permitted to operate.
When you add (actually replace hydrogens with) fluorine to an alkane, it becomes a fluorocarbon, not a chlorofluorocarbon. To get a chlorofluorocarbon, you have to add both fluorine (which doesn't destroy ozone) & chlorine (the chloro- part, which does).
ReplyDeleteFreons & halons aren't quite the same thing. Freons contain fluorine & often chlorine (but no other halogen) while halons (at least usually) contain (as well as chlorine/fluorine) bromine (which also destroys ozone). I don't think halons are actually toxic; I believe they are simple asphyxiants (if a large quantity of halons (or any other inert gas) is released it displaces the oxygen (and other gasses) in air so people can't breathe. Fire can decompose halons likely producing toxic gasses but that isn't a factor here.
Most if not all refrigerators & air conditioners made currently use refrigerants that do not contain chlorine & do not affect the ozone layer.
I meant when you add a fluorine to a molecule that already has a chlorine. I guess that wasn't clear. I've fixed it.
ReplyDeleteFreons, like I said, are just a trade name that generically include Halons sometimes. See here.[PDF]
Halons can have a direct effect on the central nervous system, though the mechanism isn't clear to me.{PDF] Though asphyxiation is definitely possible on a submarine. Still the article said poison, and while I generally don't trust the mainstream media on scientific issues, they have all the information available.
One single bond at a time for the halogens? So the Dess-Martin periodinane is imaginary? ;)
ReplyDeleteSorry Psi*Psi, someone's obviously been fucking with you. ;-)
ReplyDeleteNicely explained. Rated it "Excellent" and have linked to your posting. - Molten Eagle
ReplyDelete