Sciencemadness Discussion Board - diborane aquiring help

diborane aquiring help

chemisch - 3-11-2012 at 00:12

muy typical chemical companys dont seem to carry diborane seemed like a really useful alternative to Lah any suggestions as an individual where i might aquire most preferably in a solvent?

AndersHoveland - 3-11-2012 at 00:26

thermite magnesium reduction of boric acid
reacting resulting magnesium boride with dilute hydrochloric acid
diborane tends to spontaneously ignite on contact with air

Diborane B2H6, mixed with hydrogen, burning rapidly with a pop, when a heated steel wire (not shown in picture), but below red heat, was inserted into the tube. Diborane is very toxic, but makes a pretty green flame.

Diborane can also be more conveniently prepared in the laboratory by warming sodium borohydride with concentrated sulfuric acid (the drain cleaner variety).
http://www.flickr.com/photos/37388341@N00/3999335806/in/pool...

[Edited on 3-11-2012 by AndersHoveland]

bfesser - 3-11-2012 at 10:03

chemisch, what is "Lah"? <a href="http://en.wikipedia.org/wiki/Lithium_aluminum_hydride" target="_blank">Lithium aluminum hydride</a> <img src="../scipics/_wiki.png" /> is abbreviated LAH—ideally LiAlH<sub>4</sub>. Please put a little more effort into your posts!

[Edited on 7/9/13 by bfesser]

BromicAcid - 3-11-2012 at 10:33

Magnesium boride and hydrochloric acid can react to form diborane but this is not something I would consider a preparative method. Stock, the pioneer of borane chemistry used said reaction as his main method of preparing boranes but yields were abysmal and the reaction yields a number of higher boranes which have to be condensed and fractioned tediously. I would wager (even without searching) that most companies do not carry neat diborane, usually it is sold as a complex in THF or dimethylsulfide, search for those.

chemisch - 3-11-2012 at 13:47

bfesser i was on my phone excuse my not wanting to tediously capitalize letters. and BromicAcid i was looking for diborane in THF just was hoping someone knew of a supplier saving me the endless google search

Mailinmypocket - 3-11-2012 at 13:58

Quote: Originally posted by chemisch

excuse my not wanting to tediously capitalize letters.

Tediously capitalizing letters can make a lot of difference, when it comes to chemistry anyways. Naoh (looks like the name Noah misspelled) Whereas NaOH is easier to understand and is the correct way to write it.

Is pressing "shift" while pressing your letter selection that difficult anyways? In their defense, bfesser was not trying to be rude...

chemisch - 3-11-2012 at 14:07

no no, i realize the importance. Capitalizing on a cell phone is just a task which isn't exactly fun. Thats why it would be tedious.

Hexavalent - 3-11-2012 at 15:23

Jesus, it takes absolutely minimal effort to hold down the shift/alt button when typing.

Also, pardon my inquisitivity but what do you actually want diborane for?

chemisch - 3-11-2012 at 16:30

i'm trying not to be rude but like i stated i was on my phone... shifting on a phone is a tedious process. why i was on my phone and not my computer i have no idea. Did not know i was going to get flamed

Well Diborane would be quite useful for reducing carboxylic acids into alcohols where i could use LAH and do a work around but bleh

kristofvagyok - 3-11-2012 at 17:56

Quote: Originally posted by chemisch

Well Diborane would be quite useful for reducing carboxylic acids into alcohols where i could use LAH and do a work around but bleh

If you've got LAH, then I would suggest the standard method for generating diborane: in a gas generator place some LAH under ether and add drop-by-drop some BF3-ether complex. The LAH will react with it to form diborane.

If want to store diborane, then just bubble it in some pyridine, it could be stored this way safely and could be used easily.

P.S.: Working under argon is recommended to avoid explosions

chemisch - 3-11-2012 at 20:35

well that was my main issue that LAH i can acquire easily but i don't have the funds currently to work under argon makes sense your method but impractical just wanted to buy it lol

Nicodem - 4-11-2012 at 03:54

Quote: Originally posted by chemisch

Well Diborane would be quite useful for reducing carboxylic acids into alcohols where i could use LAH and do a work around but bleh

Why would you want to use something as exotic and hazardous like diborane for reducing carboxylic acids, when you can use standard reagents like BH₃×THF or BH₃×Me₂S solutions which are much more manageable and less hazardous, and most importantly, easy to acquire from any major chemical supplier?

stoichiometric_steve - 4-11-2012 at 05:32

Quote: Originally posted by chemisch

well that was my main issue that LAH i can acquire easily but i don't have the funds currently to work under argon

sounds a bit like bullshit, but it could just be me.

chemisch - 4-11-2012 at 12:33

see i'm still just trying to learn my classes arent moving as fast as i would like how would i be able to tell if Diborane would be able to reduce something that borane couldnt?

and stoichiometric_steve i'm a student and i just looked into using argon its not as expensive as i thought but still

kristofvagyok - 4-11-2012 at 13:12

Quote: Originally posted by chemisch

i'm still just trying to learn my classes arent moving as fast as i would like

Best way of learning chemistry is to get good books and not blowing up yourself. Trust me.

chemisch - 4-11-2012 at 13:43

just to note my attempts to aquire diboarne were not in the relative future more like 6months to a year so by all means i wasnt trying to blow myself up

stoichiometric_steve - 5-11-2012 at 15:54

so basically you don't know shit about the stuff you're trying to attempt, eh? you're a waste of time.

chemisch - 5-11-2012 at 20:28

no. that's incredibly rude. i was simply trying to figure out the practicality of acquiring diborane most of the feedback was quite helpful and i appreciate it alot. Steve, for your information the whole idea behind forums/Threads is to waste time... if you don't want to contribute by asking or attempting to answer questions don't post simply to bash me that's not fun

AndersHoveland - 6-11-2012 at 03:36

Quote: Originally posted by BromicAcid

usually [borane] is sold as a complex in THF or dimethylsulfide, search for those.

In some situations, the reactivity of diborane is significantly different from that of borane in the form of an adduct with ether.

Dr.Bob - 6-11-2012 at 06:32

I will agree that diborane may react differently than BH3-THF, but most acids reduce fine to alcohols with BH3 in THF or DMS, usually works at RT but can be heated gently if needed. If that does not work, due to sterics, then LAH at reflux is the next best way (always best to add the substrate to the LAH slurry in THF for best results, in my experience). Very few practicing chemists I have met would use diborane for that, just too hazardous and hard to work with, compared with just squirting in a soln. of BH3 in THF. Similar to using triphosgene rather than phosgene or dipinacol borane rather than pinacol borane, since they are less hazardous and cheaper/easier to ship.

chemisch - 6-11-2012 at 10:07

How would I find out if DMS or borane would reduce indoor-3-acetic acid for example?

chemisch - 6-11-2012 at 10:24

Wait I was getting DMS confused are you referring to DMS as a solvent?

chemisch - 6-11-2012 at 10:28

OK I got this I got confused for some reason I thought you were talking about DMSO which was really confusing me

Dr.Bob - 6-11-2012 at 12:00

Quote: Originally posted by chemisch

How would I find out if DMS or borane would reduce indoor-3-acetic acid for example?

Not sure how to reduce indoor-3-acetic acid, but if you are looking to reduce indole-3-acetic acid to indole-3-CH2CH2OH, that might be doable. A simple search showed over 10 literature refs, most of which used LAH or DIBAL for the reduction. There are none for borane or diborane listed for the unprotected NH on the indole, so it may be that borane reagents complex with it. Many more use the methyl ester, which is much more easily reduced.

Do a literature search. If you have access to Scifinder, Reaxys, or a library with some chemistry database, try it. But even Google and wikipedia can produce some papers on nearly any chemistry subject now.

[Edited on 6-11-2012 by Dr.Bob]

chemisch - 6-11-2012 at 13:21

Yeah that's what I was looking to reduce the carboxylic group to ethanol I found literature stating that diborane would do it at room temp but like previously stated its quite exotic not sure if I have access to those databases but I'll ask around

Hopefully my local university has those resources

[Edited on 6-11-2012 by chemisch]