Sciencemadness Discussion Board

Lithium Aluminum Hydride / Lithium Hydride recovery from Tetrahydrofuran solution?

APO - 16-9-2013 at 13:44

A while back I was reading on here about reducing agents. Along the way I came across a thread that stated Lithium Aluminum Hydride and Lithium Hydride cannot simply be separated from a Tetrahydrofuran solution by evaporation, that it formed a complex similar to Lithium Bromide in N-Butyl Lithium or Methyl Lithium. It listed some method of precipitating the Lithium Aluminum Hydride or Lithium Hydride back out of the Tetrahydrofuran, somewhat similar to forcing Hexanitrohexaasaisowurtzitane out of Ethyl Acetate with Chloroform but without adjusting it's form. Is it true that Lithium Aluminum Hydride and Lithium Hydride can't easily be separated from Tetrahydrofuran once dissolved? Is it true that they form a complex of some sort? If not, can they be separated by simple evaporation, say under a vacuum environment?

[Edited on 17-9-2013 by APO]

kristofvagyok - 16-9-2013 at 13:59

LiH is almost insoluble in tetrahydrofuran, while LiAlH4 is well soluble, so the separation is easy, just filter it.

Just a comment: if you write sentences without abbreviations, e.g.: you write lithium aluminium hydride instead of LAH, or just LiAlH4, than it could be much more easily interpreted by others...

APO - 16-9-2013 at 14:40

No, I meant getting back either of them out of separate solutions, not from a mixture. I heard once they're dissolved that they're difficult to get out.

Abbreviation or Ignorance

bfesser - 16-9-2013 at 14:45

IIRC &mdash; <em>If I Recall Correctly</em>
LAH &mdash; <a href="http://en.wikipedia.org/wiki/Lithium_aluminium_hydride" target="_blank">lithium aluminium hydride</a> <img src="../scipics/_wiki.png" /> <em>(easy enough to just write LiAlH<sub>4</sub>;)</em>
LH &mdash; <a href="http://en.wikipedia.org/wiki/Lithium_hydride" target="_blank">lithium hydride</a> <img src="../scipics/_wiki.png" /> <em>(properly abbreviated LiH)</em>
THF &mdash; <a href="http://en.wikipedia.org/wiki/Tetrahydrofuran" target="_blank">tetrahydrofuran</a> <img src="../scipics/_wiki.png" />

Sometimes I think that people who abuse abbreviations use them because they don't rightly know what they stand for. Unless you're one of those people (I despise) who type only with their index fingers, it wouldn't kill you to just write out what you mean. If you are one of those people, it takes a week maximum to learn to type properly&mdash;an invaluable skill. I don't understand the excuses of the elderly, either... the computer keyboard is based on the typewriter layout. Nobody is still alive who was born before the invention of the typewriter (they would be approximately 150 years old).

&lt;/disgruntled rant&gt;

APO - 16-9-2013 at 18:23

Sorry I didn't know that abbreviations are such a big deal, many threads on here have them in great abundance, so I figured since I was feeling a bit of carpel tunnel from writing an essay for school, that using some acronyms wouldn't be such a bad idea. Anyway, I edited my initial post, and elaborated what I recall reading, and I included some examples that they reminded me of.

bfesser - 16-9-2013 at 18:41

No worries, I'm just a bit cranky today&mdash;trying to set up a server to seed the latest forum backup, and failing. Please don't take my post personally, it's merely my grudge against laziness in general. Acronyms are fine, but it's best to define them before use; unless they're ubiquitous chemistry acronyms that everyone here should know (e.g. THF).

APO - 16-9-2013 at 19:29

It's fine, my whole lab was recently confiscated by the police, along with most of my personal belongings such as my computer, camera, phone, and about two grand worth of chemistry/engineering supplies and equipment for my projects. Not to mention countless issues brought on by this. Long story short, I get it since I got a lot on my plate too.

Bot0nist - 16-9-2013 at 19:58

Why? How old are you, if you dont mind me asking? My limited experiance with law enforcment officers has varied greatly from that. Must be the circumstances...
Sorry to go OT, but that subject intrests me currently

APO - 16-9-2013 at 20:13

Me and my sister got in a fight, I was covered in blood and in need of medical attention, once the police arrived after I called 911, they saw everything in my room and suspected I was running a meth lab, so they called in the hazmat team. After five weeks of scrupulous testing they found no evidence of any illegal activities. They insisted it was a hazard, once I told them my safety procedures, they said it was inappropriate. It's been over six weeks without my lab equipment, computer, camera, phone, and other confiscated items. I just turned fourteen late last month.