Talk:Halocarbon

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This article, originally a redirect to the excellent article on haloalkanes, was expanded into a full article in order to provide a common source of information about the several chemical families of halogenated organics. These compounds have been beacons of modern industrial chemistry. At the same time, together with petroleum distillates, they have proven to be the most challenging of the modern environmental pollutants.

Craig Bolon 04:08, 27 January 2006 (UTC)

Disputed[edit]

This artuicle implies that all halocarbons are hazardous and are very carefully regulated. This is not true. Some halocarbons are not hazardous and are very common, like polytetrafluoroethlyene or teflon, which is just polymerized C2F4. Also, dichloromethane is still often used in household products (see its uses). Also, R-134-a, a flouroalkane, is often used as a refrigeratnt and it computer cleaning products (comperessed gas is used to blow away dust) since it is not ozone depleting. While some halocarbons where banned and are unsafe, this article needs to state more clearly that not all of them are regulated heavily and are dangerous. Also, not all of them are unreactive, acid halides (like acetyl chloride, CH3COCl) and a few other species are very reactive (unlike most halocarbons). Also, some species (like HCFCs, chlorophenols, and HFCs are too voatile or reactive to persist in organisms and bioaccumulate. Polonium 00:26, 17 April 2006 (UTC)

Addressing objections[edit]

The above comment claims "some halocarbons are not hazardous." Not proven. Such assertions recall the promotion of halocarbons in the decades from the 1930s through the 1960s. Manufacturers tended to stress benefits and discount hazards. Some hazards, such as chloracne, were gross and should have been obvious, while others, such as ozone depletion, were subtle and took years of effort to understand.

As the article says, all halocarbons, including PTFE, dichloromethane and refrigerant R-134a, are potentially hazardous when exposed to high temperatures, because they decompose, releasing free halogens and other toxins. Given decades of effort that it has taken to recognize and cope with halocarbon hazards, any statement about current regulations should be provisional, as the controversy over PFOA in recent years clearly illustrates.

The comment about acid halides does make sense, although practically it is limited to reactive intermediates rarely encountered outside chemical process enclosures. A qualification has been added to the article. The one trying to distinguish hazards on the basis of volatility does not. Refrigerants of similar volatility differ widely in their potential for ozone depletion.

Craig Bolon 16:32, 20 April 2006 (UTC)

request merging Organic halide to this article[edit]

Organic halide started out as redirect to haloalkane but this article much better covers the concept. V8rik 20:05, 30 April 2007 (UTC)

  • Done. V8rik 15:38, 5 May 2007 (UTC)
I haven't been privy to any discussions related to this topic, but in my view and experience, when organic chemists talk about halocarbons, they mean compounds that contain only carbon and halogen, and occasionally those which might have a single hydrogen in addition to multiple halogens (sometime called hydrohalocarbons). The absence of hydrogens gives very special chemical properties to these materials (i.e. PTFE, many of the Freons, CCl4 as inert solvent for radical reactions, etc) which resulted in the special class name halocarbons being coined. Compounds like Me-Cl would not be considered halocarbons, CCl4 would be. This is an extension of names like hydrocarbons (only hydrogen and carbon), cyanocarbons (each carbon fully substituted with CN groups, the WP article on this also over generalizes this name), lithiocarbons (materials like C2Li2 and CLi4), oxocarbons and even the original use of carbohydrates. I think "Organic Halides" would be the proper title for this article, usually subdivided into the various classes which determine important reactivity characteristics of the halide (alkyl halides, aryl halides, vinyl halides, allyl halides, etc, and, of course, halocarbons). Halocarbon is a nice snappy name, but it should not be used in this very general way. ChemistHans 17:00, 20 August 2007 (UTC)

Hi ChemistHans, you have made a good point, a name change to organic halide or organohalide would be a good idea. I also note that the distinction between halocarbon and haloalkene is not explained in the haloalkane article V8rik 21:08, 20 August 2007 (UTC)

I'm not experienced enough with WP to make such a change. I first noticed this in articles which referred to the Halocarbon page: n-Butyllithium (where I removed the link) and Organolithium reagents (it's still there). —The preceding unsigned comment was added by ChemistHans (talkcontribs) 22:42, August 20, 2007 (UTC).

Classifications[edit]

i think the classifications would be better reworked like this:

-Shootbamboo (talk) 04:41, 28 November 2008 (UTC)