Using Ionic Liquids To Replace Organic Solvents

An Anonymous Coward writes: "The NY Times (free reg required) has a story about ionic liquids possibly taking over from some of the nastier organic solvents. Apparently these things have been around since the 40s, but are only just getting a lot of attention now. They are supposed to be a lot more environmentally friendly, offer all sorts of wonderful properties for carrying out chemical reactions, and so on. They may be cool and different, but are they really better? Salt on the roads in the winter causes all kinds of problems -- aren't other kinds of salts going to cause problems in large quantities? On the other hand, cool and different is good too."

Comments

Another alternative

[cperciva]

Another alternative is to use supercritical water. (ie, water at high pressures and temperatures). Apparently the chemistry of water changes dramatically as the temperature and pressure are increased, and it becomes pretty non-polar, and consequently can act as a solvent for all sorts of messy organics.

At least, that's how I understand it -- it isn't my research or even my field so I don't really understand any of the details.

Re:How does this work?

[meridoc]

There's a difference between polar and ionic. Yes, the rule is "like dissolves like," so polar things dissolve polar things (and non-polar things dissolve non-polar things). Water and table salt are both polar; table salt (NaCl) also happens to be ionic.

An ionic compound simply means that the pieces basically are held together by charge attractions. In the case of NaCl, chlorine is pulling so hard on the lone electron from sodium that it is almost removed; consequently, Na has a (net) postive charge and Cl has a (net) negative charge. The whole "opposites attract" thing keeps Na and Cl together as a tiny part of a table salt crystal.

Nasty organic solvents are not always polar. Benzene, methane (and other pure carbon-hydrogen chains) are not. Water is highly polar, but because the earth has lots of water, it's cheap and available. Phenol and Xylene are very nasty and very polar. Acetone's not so bad (on a smallish scale).

The NY Times article mentions "the salt," which may be confusing. A salt, in chemical terms, includes a whole family of things and is not limited to NaCl. Neither article intends on using sodium chloride as the ionic solvent (I don't think) because it has a high melting temperature (which is a good thing for the salt shaker in my cabinet). What the researchers in the articles are proposing is a substance that is ionic (like table salt, but not necessarily polar) that has large constituents so that the solvent would not get in the way of the desired reactions.

Anyone else notice..

[Muad'Dave]

the horrible chemistry 101 mistake?

"Sodium chloride, the chemical name of table salt, consists of equal parts of sodium and chloride."

That's like saying Prozac(tm) consists of equal parts Pro and Zac.

Or you can try...

[Big Brass Balls]

here. No need for that poofter registration bullshit.

--
Do I play Hockey?
Posting at -1 since April 18/01.