johnon50 - 5-1-2007 at 14:34
in this month's Analog, theres a reference to beach sand being dissolved in ethylene glycol + NaOH; anybody heard of this?
Dr. Beaker - 5-1-2007 at 14:57
this sounds trivial. NaOH disolved in ethylene glycol, and then sand (silica) is disolved in the basic solution. the only (relatively) interesting
thing is that Na2SiO3 is soluble in (CH2OH)2.
Ozone - 5-1-2007 at 17:52
The action of molten Li (~180°C) is quite impressive on glass; it makes an exciting laboratory demonstration. It appears that the salts, specifically
LiNO3, are also quite aggressive; please see:
http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/1935/57/i04/...
It also appears that Li can attack Si carbide as well:
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1151-2916...
For excellent coverage of HF, check out Woelen's website here:
http://www.oelen.net/science
Have fun, be Careful!
O3
ferrocene - 5-1-2007 at 19:34
Yes, I've heard of it.
It came out of a research group I worked in at the University of Michigan.
The compound produced is a modestly interesting penta-coordinate silicon compound.
Of somewhat greater interest is the fact is that the base can work in catalytic quantities.
Interesting that it would show up in Analog more than 10 years after the initial work was published.
Mr. Wizard - 5-1-2007 at 19:46
I have noticed that a small piece of the Lithium foil, from a dead Lithium battery, 2 cm x 1 cm; when burning will burn an impressive hole in a
concrete driveway, almost a cm in diameter. 
chemoleo - 5-1-2007 at 20:27
Question is, under what conditions does it dissolve? High temperature, high pressure, or benign conditions?
I'd sure find it surprising for it to dissolve readily at say, RT.
ferrocene - 5-1-2007 at 22:28
The dissolution happens at the boiling point of ethylene glycol, about 200 C. At that temperature water, the other product of the reaction, boils off.
The rate of reaction, is, of course, dependent upon the surface area of the silica. Fumed silica (<10 nm particle size) will dissolve in a few
hours. Sand takes quite a bit longer. And yes, Pyrex dissolves, too, given long enough.
Triethanolamine works quite well as the base for this reaction. The triethanolamine forms a tri-dentate chelate (well, almost tetra-dentate, with a
weak bond to the N possible) with the silicon, the fourth valence being taken up with an ethylene glycolate.
Ozone - 5-1-2007 at 22:46
Mr. Wizard,
'Tis wicked on the sand! For glass it need not be burning--molten will do; the reaction with the glass provides enough enthalpic heat to maintain the
spontaneous reaction (but I bet the burning stuff is neat!). It's not so good on skin either!
You ought to see what happens when, ahem, one is foolish enough to try to solder a wire onto a Li button cell... The etherial solvent bursts the case
and ignites whilst spraying molten Li all over.
*message* We were pulling Li metal out of my friend's hand (quickly!)--whew. Not good. It was *ugly*, but he said it did not hurt much (I suspect
nerve damage). He healed up well though, and hospitalization was not required.
If the solution conditions are relatively mild using the glycol-alkali, that would be the novelty. Ferocene, can you point to good inside references
for this stuff?
Any ideas on supercritical water?
Cheers,
O3
ferrocene - 5-1-2007 at 23:16
For example:
"SiO2 as a Starting Material for the Synthesis of Pentacoordinate Silicon Complexes‚" Chemistry of Materials, 1994, 6, 2177-2192.
This chemistry was first explored several years earlier. IIRC, there are some early papers in Nature that describe crystal structures and synthetic
routes of the ethylene glycol compounds themselves. This paper will have all of those references.
Over the years, we've tried to figure out what to do with the stuff. There are ideas, but nothing truly useful of which I'm aware.
thanx
johnon50 - 10-1-2007 at 09:59
thanks folks! have some ores high in silicates and that looked interesting. excellent info on pentacoordiate silicon.