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Author: Subject: The short questions thread (3)
Mixell
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[*] posted on 14-8-2011 at 18:03


When a bond is created, it releases the equivalent energy of the bond to the environment, right?
So for the reaction to be thermodynamically favorable, the energy of the bonds that are created should exceed the energy of the bonds that are broken?
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Morgan
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[*] posted on 23-8-2011 at 18:12
Plastics Ben


I have a heavy box of quarter inch thick 6 X 24 inch sheets of a milky white plastic with a glossy surface and paper coating each side to protect from scratches. But I don't know what kind of plastic it is. It is unaffected by acetone. Any ideas what tests I could do to determine the plastic?
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watson.fawkes
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[*] posted on 24-8-2011 at 05:28


Quote: Originally posted by Morgan  
I have a heavy box of quarter inch thick 6 X 24 inch sheets of a milky white plastic with a glossy surface and paper coating each side to protect from scratches. But I don't know what kind of plastic it is. It is unaffected by acetone. Any ideas what tests I could do to determine the plastic?
It's most likely to be an acrylic polymer, as that's the bulk of tinted sheet plastic out there. Second most likely is polycarbonate, but I don't often see it tinted in trade.

Do you want to know the chemical composition for using it as a reagent, or do you want to select an adhesive, or something else?
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Morgan
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[*] posted on 24-8-2011 at 16:20


It was just some plastic leftover from a photography business where they would mount pictures to it and then cut around the figures with a bandsaw making little statues of a sort of people, pets, etc.
I thought I might find some use for it but wanted to know if it was acrylic or polycarbonate, my two guesses as well. I have been playing around with electrostatics lately and might use it in some way.
I could make one of these only 6 inches instead of CD size.
http://www.youtube.com/watch?v=R9JVSWfgleg
Or perhaps as a plastic base for an electrophorus if it is a good plastic for that.
http://www.youtube.com/watch?v=TO95iGtRVv0
Or maybe I could employ it as an insulator or structural component It's funny how sneaky high voltage is, how it can crawl over surfaces. I experienced that with this device I made a few weeks ago. It's odd how entertaining two thin streams of water can be.
http://www.youtube.com/watch?v=h4WvZAVQtjk

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watson.fawkes
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[*] posted on 25-8-2011 at 02:56


Quote: Originally posted by Morgan  
I have been playing around with electrostatics lately and might use it in some way.
Whatever the chemical composition, it should be just fine for this. While you'll likely get better performance out of a specialty material, what you've got is good enough for basic experiments. My only advice is to clean the surfaces carefully before putting the material into service, in case there's a more-conductive surface coating or residue from the protective paper.
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Mixell
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[*] posted on 29-8-2011 at 06:29


What is the best way to reduce a solution of palladium nitrate to metallic palladium? May be aluminium metal in conjunction with chloride ions?
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Picric-A
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[*] posted on 29-8-2011 at 10:49
Benzhydrol Refusing to Crystallise


I reduced 8g of benzophenone with 3g sodium borohydride (1g excess- the borohydride was old and i though better excess than not enough) in 50ml of methanol. Refluxed for 2 hours then boiled off 25ml of methanol. The remainding cloudy solution was added to 200ml of ice cold water with 50ml of 20% HCl in.

At this point the benzhydrol should crystallise, instead i got a very slightly yellow oil remaining at the bottom and the aqeous layer went opaque white.

What is going on here and why is the benzhydrol not crystallising?

I tryed the reaction again on smaller scale and the exact same happened, no crystallisation at all :(
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bbartlog
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[*] posted on 29-8-2011 at 12:45


Quote: Originally posted by Mixell  
What is the best way to reduce a solution of palladium nitrate to metallic palladium? May be aluminium metal in conjunction with chloride ions?


I would suggest ascorbic acid. But I don't know what the best way is and suspect it will depend on what you're trying to do. I suspect aluminium might have problems, either due to passivation or because aluminium nitrate is itself an oxidiser (but this I assume could be addressed by using enough elemental aluminium).
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Mixell
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[*] posted on 31-8-2011 at 15:11


Anybody knows what is the color of bismuth nitrate solution?
I would have expected it to be yellow/colorless, bur for some reason mine is green (made from nitric acid and bismuth, which was sold as 99.9% purity).
I added the nitric acid to the bismuth, and surely, a vigorous reaction has started (, I continued adding nitric acid when the vigorous bubbling had stopped (at this phase the solution was yellow), then I left it for 10-15 minutes and when I came back, the solution turned green. At the moment a small amount of bismuth is still dissolving in it, but it has retained its green color.

[Edited on 31-8-2011 by Mixell]

[Edited on 31-8-2011 by Mixell]
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Picric-A
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[*] posted on 2-9-2011 at 13:46


Green is probably dissolved NO2. This can be dealt by adding small quantities of urea which causes it to give off nitrogen forming the colourless solution. Alternativly passing a warm stream of air through the solution works.
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Mixell
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[*] posted on 2-9-2011 at 15:35


After passing large amounts of warm air through the solution, it is still quite yellow-green...
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solo
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[*] posted on 3-9-2011 at 14:41


Sodium Cyanoborohydride- A highly selective reducing agent for Organic functional groups
Cinto F.Lane
Synthesis
1975; 1975(3): 135-146
DOI: 10.1055/s-1975-23685


.....on page 144 the study talks about the dehalogenation while showing inertness to towards almost all functional groups, I'v iodated my primary alcohol with Hpo and I2 and resulted with an iodated OH as an HI salt , insoluble in water ....now DMSO can substitute Hexamethylphosphori triamide (HMPA), ....finally my question how is the w/u with NaCNBH4 not familiar with it , but sure its not the same as with NaBH4....Trying not to kill myself doing this procedure.....some have suggested using using ammonium chloride to kill the reaction while I thought of using Na2CO3.....I have searched but not found anything to satisfy me to go on.....thanks....solo


P.S.

I saw this ...."Tetrahydrooxazines 6c,h,i; General Procedure Using Method A
NaBH3CN (0.095 g, 1.5 mmol) was added to a stirred soln of oxazine
4c, 4i, or 4h (0.5 mmol) in AcOH (2.2 mL) under argon. The
mixture was stirred at r.t. for 2 h and poured into a mixture of EtOAc
(100 mL) and sat. Na2CO3 (100 mL). The aqueous phase was backextracted
with EtOAc (2 × 50 mL); the combined organic layers
were washed with brine (50 mL) and dried (Na2SO4). The solvent
was evaporated in vacuo and the residue was subjected to column
chromatography (silica gel).


...source,




Diastereoselective Synthesis of γ-Amino Acids and Their Derivatives from Nitroethane via Intermediacy of 5,6-Dihydro-4H-1,2-oxazines Bearing the CH2CH(CO2Me)2 Substituent at C3
Alexey Yu. Sukhorukov,
Synthesis
2009(5): 741-754
DOI: 10.1055/s-0028-1083360


http://ifile.it/3kzxacy


....although not the same reaction but the work up makes sense, pick up the organic material with the ethylacetate and kill the boro with the Na2CO3....but then i may be overreading in order to go forward....still need some input....

Attachment: sodium.cyanoborohydride.pdf (662kB)
This file has been downloaded 424 times



[Edited on 3-9-2011 by solo]




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Mixell
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[*] posted on 5-9-2011 at 09:24


Anyone knows what is the full reaction mechanism of dissolution of aluminium in the presence of hydroxide ions? A reference would be great.

Never-mind, managed to dig it up myself, if anyone else is interested: http://www.icnet.dk/alhiref/I0009EDC4.0/DOE%20aluminium_wate...

[Edited on 5-9-2011 by Mixell]
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questions
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[*] posted on 5-9-2011 at 19:51
temp


Hey guys, here's a random question;

If I were to take an ordinary glass jar (not made from pyrex or anything similar) and submerg it into acetone with dry ice in it at the temperature of around -77C, would it crack?
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6-9-2011 at 18:57
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[*] posted on 8-9-2011 at 13:29


I just saw bitter almond aroma in grocery store, is it same stuff as bitter almond oil, and is there benzaldehyde in it?

edit. did some hard searching in english and found that its ethyl alcohol and propylene glycol and almond aroma.So is almond aroma chemically what?

[Edited on 8-9-2011 by Roger86]
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[*] posted on 9-9-2011 at 07:50


It will almost certainly be a weak solution of benzaldehyde.
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[*] posted on 9-9-2011 at 10:30


How would I oxidize polystyrene to form styrene?



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solo
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[*] posted on 9-9-2011 at 17:27


Reference Information


Method of reclaiming styrene and other products from polystyrene based materials
US Patent 6018085

Abstract
A method of reclaiming styrene from polystyrene-containing materials contaminated with animal fats and/or vegetable oils. A solution of polystyrene from such materials in a solvent is heated in distillation equipment to depolymerize the polystyrene and produce a styrene fraction and a heavier fraction, the styrene fraction being separated from the heavier fraction. Prior to heating, an inert gas is used to purge the distillation equipment of oxygen. The method preferably is carried out at the lowest temperature which will achieve the desired rate of depolymerization.

Attachment: Method of reclaiming styrene and other products from polystyrene based materials .pdf (250kB)
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[*] posted on 9-9-2011 at 18:09


Anybody have some information on this product, what combination of chemicals might it be made of?
http://www.uksealants.co.uk/product.asp?idproduct=91
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[*] posted on 9-9-2011 at 18:35


http://lmgtfy.com/?q=calofer&l=1

Looks like it's primarily sodium silicates. More trouble to separate than it's worth.

I wouldn't recommend using the short questions thread as a substitute for Google.

[Edited on 9/10/11 by bfesser]
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[*] posted on 9-9-2011 at 21:37


Quote: Originally posted by questions  
Hey guys, here's a random question;

If I were to take an ordinary glass jar (not made from pyrex or anything similar) and submerg it into acetone with dry ice in it at the temperature of around -77C, would it crack?


depends at what temperature the glass jar is at, if its at -77C, no it won't fail, if its at 400C, yes most likely it will fail. At room temperature its likely to fail depending on its design, cooling it slowly would minimise the chances of it failing, however it would not stop it smoking cigarettes, and as we all know, these cause cancer.




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Morgan
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[*] posted on 10-9-2011 at 01:19


Quote: Originally posted by bfesser  
http://lmgtfy.com/?q=calofer&l=1
Looks like it's primarily sodium silicates. More trouble to separate than it's worth.
I wouldn't recommend using the short questions thread as a substitute for Google.

I spent a few hours reading about K and Na silicates and the hardening process using CO2 or other agents. I had already used Google, imagine that. It's those other proprietary ingredients I was interested in, kind of a materials science point of view.
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[*] posted on 12-9-2011 at 01:08


If a reaction requires Raney nickel catalyst, can it be replaced with really fine powder of nickel, if i expect the reaction to need a lot more hydrogen?

I read somewhere that it should work, but i'd need 75% more hydrogen, but since hydrogen is dirt cheap, it's not really a problem.
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[*] posted on 12-9-2011 at 05:39


Probably depends on just what you mean by 'really fine powder'. I would also expect that the first thing you would need more of is time, not hydrogen, but without a pointer to whatever it is you read I suppose I'm just guessing.
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[*] posted on 12-9-2011 at 11:19


Quote: Originally posted by Roger86  
If a reaction requires Raney nickel catalyst, can it be replaced with really fine powder of nickel, if i expect the reaction to need a lot more hydrogen?

I read somewhere that it should work, but i'd need 75% more hydrogen, but since hydrogen is dirt cheap, it's not really a problem.


Depends on how the 'realy fine' powder has been made. Most fine powders bought commercially have an oxide layer which will prevent hydrogen adsorbtion, rendering it useless for catalylyst use.


If you find a way of making very fine Ni powder under an inert atmosphear/liquid, then that should be usable as a catalyst.
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