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Author: Subject: The Short Questions Thread (4)
Metacelsus
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[*] posted on 15-10-2013 at 17:42


What conditions are you storing it under, and for how long? A good starting estimate would be about 1 gram per 100 milliliters.



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[*] posted on 16-10-2013 at 14:17


It's stored in a brown glass bottle with a teflon-lined plastic cap, at room temperature, in a flammables cabinet. I'd like to put some molecular sieves in the bottle to scrub up any water that might end up in there anytime the bottle is opened.

What is your 1 gram per 100 milliliters suggestion based on?

My best guess is that the maximum I would ever put in is 34 grams. I came to this number by the following calculation:

500 mL of ether can dissolve 7.5 grams of water at room temperature (1.5 grams H20/100mL ether).

The manufacturer of these sieves claims they will absorb 22% of their own weight in water at 25 C.

To absorb the maxmium 7.5 grams would require 34 grams of molecular sieves.

That seems like overkill, but it's the only reasoned estimate I can come up with without advice from someone else with experience.
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Metacelsus
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[*] posted on 16-10-2013 at 14:47


My estimate is based on the procedure we use to store NMR solvents at the lab I work at. I assume you will pre-dry your ether, and the sieves are just to keep it dry during storage. In that case, you probably won't need 34 grams of sieves.



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[*] posted on 16-10-2013 at 14:55


I think you're right. The 34 grams was the maximum I could imagine using, and really seems like overkill.

Thank you for your input, Cheddite Cheese.
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bismuthate
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[*] posted on 19-10-2013 at 04:44


How would NaBH4 react with chlorine?



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Metacelsus
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[*] posted on 19-10-2013 at 07:17


My guess:

NaBH4 + 4 Cl2 -> NaCl + BCl3 + 4 HCl




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bismuthate
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[*] posted on 19-10-2013 at 09:37


Thank you that could be a unique way to make boron if passed over a reducing agent.



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Metacelsus
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[*] posted on 19-10-2013 at 11:09


In my opinion, it would be near sacrilege to use (waste) sodium borohydride to isolate boron. Why not reduce boron trioxide with magnesium or aluminum?



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bismuthate
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[*] posted on 19-10-2013 at 11:15


Don't worry I'm would be making my own impure LiBH4 from boric acid, methanol, lithium ( I can get as much as I need), and hydrogen. I am in an unfortunate circumstance that does not allow me to make the trioxide.
Plus I'm making a creative method:D.




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[*] posted on 21-10-2013 at 10:41
How to make copper gluconate


I really need help with this reaction. I´m trying to make as many as possible compounds of copper and now my challenge is to make copper(II) gluconate. The idea is to get some gluconic acid and let it react with copper carbonate or copper hydroxide. I tried to oxidize glucose by reaction with iodine potassium iodide solution and sodium hydroxide then adding copper carbonate, the final solution was green/blue .. after heating it up it completely lost the color and nothing crystallized out after evaporating water. Anoyone knows where the problem is or better way to make my reaction succesful? :/

[Edited on 21-10-2013 by Hegi]
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[*] posted on 1-11-2013 at 05:37


In Tetrahedron 46 (1990), p. 7454 beta-nitrostyrene is reduced to the amine with BH3/THF generated in situ. Hydrolysis is performed with 1N HCl at 80-85°C for 2 h.

Is this really necessary? I thought boranes can be hydrolized by acidification at RT?
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[*] posted on 2-11-2013 at 03:12


Borane itself is very readily quenched by the addition of water at 0*C. In the reduction of amides and nitro groups however, the product amine complexes any excess borane as the amine-borane adduct, which can be a great deal more difficult to hydrolyse (and thus release the free amine). Heating with 1M HCl is a common method, but I've found a patent (http://www.google.com/patents/WO2007106459A2) that suggests methanolysis in the presence of a catalytic amount of transition metal salt at ambient conditions. I suspect the amine tetramethylborate salt that results is readily hydrolysed by dilute acid, or perhaps even water.

[Edited on 2-11-2013 by DJF90]
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[*] posted on 3-11-2013 at 01:03


Thanks! That makes sense. I never realized amine/borane adducts were that stable. :o
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[*] posted on 3-11-2013 at 01:04
Question


Im thinking of sythesizing some sodium hydroxide since its impossible to buy it where i live

would this reaction work?
Ca(OH)2(aq) + Na2CO3(s) → CaCO3↓ + 2 NaOH(aq)
the solution would then be filtered to remove the CaCO3 and be evapourated to dryness in a suitable container to resist corrosion.

any idea on what container to use?
I'd rather not use glass as i dont want to contaminate the product with silicates.



[Edited on 3-11-2013 by confused]
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[*] posted on 3-11-2013 at 03:50


NO! That reaction will not work, they just won't react.
You can make it by eletolysis.
gloss is just fine.

[Edited on 3-11-2013 by bismuthate]




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[*] posted on 3-11-2013 at 04:07


It will work, simpl have to boil the two together long enough. It used to be an industrial process.



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[*] posted on 3-11-2013 at 04:16


Oh! Well then I apologize. You shouldn't use glass for this one.



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[*] posted on 3-11-2013 at 04:29


in which case, what container would you reccomend that resists strong bases at elevated temperature
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[*] posted on 3-11-2013 at 04:34


Well, steel works along with copper plated containers.



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[*] posted on 3-11-2013 at 04:43


Nickel is resistant all the way to molten NaOH.

[Edited on 3-11-2013 by hyfalcon]
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[*] posted on 3-11-2013 at 04:52


Try aluminum *makes troll face*
You can silver plate glass and plate nickel or copper over that.There's a whole thread on it.




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[*] posted on 3-11-2013 at 05:03


would stainless steel work?
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[*] posted on 3-11-2013 at 05:52


Take a look at this neon sign transformer. http://www.ebay.com/itm/NEW-12-000-volt-12kV-NEON-PRO-SIGN-P...

If you look at the description, it has a whole long speech about it not being able to be used as a power supply for jacob's ladders, tesla coils, ect... It also says trying to use it for something like that will void the warranty. Here's my question: Are solid state NST's like this unable to be used for anything other than neon signs, or are they just trying to deter people from using them for those projects? (I don't care about voiding the warranty)




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[*] posted on 3-11-2013 at 07:26


that seems to be one of the newer switch mode power supplies their alot higher frequency than iron cored NST. Im not entirely sure how it will affect using it for such projects.

Ideally you would want to use a iron cored neon sign transformer for such projects. But i can see how shipping would be a killer, try and find somewhere that makes neon signs, they'll probably have a few NSTs lying around

Quote:
The newer switch mode NST’s are not ideal for Tesla coil use as they have built in GFI ground fault protection, short circuit protection and their components cannot withstand high frequency radio currents – they will simply be fried if they work at all under Tesla coil conditions!

http://www.google.com.sg/url?sa=t&rct=j&q=&esrc=...

[Edited on 3-11-2013 by confused]
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[*] posted on 10-11-2013 at 09:11
Is this reaction possible?




I've been wondering that nforming polyethyleneoxide and polyethyleneglycol is a well known reaction, what could be done with basic or acidic catalyst, but high molecular weight polymerc could be broken down? I've been wondering on producing dioxane from PEG, anyone any idea?
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