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Ramium
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[*] posted on 8-6-2016 at 01:09


Can sulphur be used as a stabilizer for acrolein?
If not, are there any other effective stabilizers besides hydroquinone?




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[*] posted on 8-6-2016 at 14:39
Glassware cleaning question


I have managed to get some fine sulfur precipitate on the inside of a PE funnel. (Don't ask.) I would like a simple efficient way of removing it -- obviously there are parts inaccessible to mechanical scrubbing.
My first thought is to sluice a few times with warm xylene but there might be better options.




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[*] posted on 8-6-2016 at 16:37


just hung it on a string in the flood waters j_sum :D



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[*] posted on 8-6-2016 at 16:51


Quote: Originally posted by j_sum1  
I have managed to get some fine sulfur precipitate on the inside of a PE funnel. (Don't ask.) I would like a simple efficient way of removing it -- obviously there are parts inaccessible to mechanical scrubbing.
My first thought is to sluice a few times with warm xylene but there might be better options.


Hot H2SO4 will remove it but that might not be as attractive as xylenes. Also, the PE may melt. Xylenes is probably still your best bet.




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[*] posted on 8-6-2016 at 17:19


It depends upon what solvents that you have and their cost,
e.g. CS2 is a good solvent but expensive, DCM is a poor but cheap solvent,
I have read woelen recommend hot toluene on another forum.
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[*] posted on 8-6-2016 at 17:28


Yeah, I could use CS2. But the stuff is so volatile I am likely to have some evaporate and still leave a bit of residue behind.
Xylene I believe is better than toluene. But maybe I could react it with something?...




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[*] posted on 8-6-2016 at 18:09


Would Piranha solution attack the sulphur ?
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[*] posted on 8-6-2016 at 18:11


I guess it would but I am really not equipped for that.



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[*] posted on 8-6-2016 at 18:12


I'm not sure how available nitrates are in Aus currently, but one method which I find quite effective to remove organic tars(I've heard it works for sulfur too, haven't tried it) from condensers and flasks is to simply prepare some nitric acid with the contaminated glassware. The hot nitric acid oxidizes anything organic(or sulfur hopefully) to either gaseous(CO<sub>2</sub> and H<sub>2</sub> for organics) or liquid forms. With sulfur you would form either sulfur dioxide or sulfuric acid, neither one is a big deal since they're being used in the preparation anyway so the resulting acid wouldn't be significantly contaminated. Worst case, it needs to be redistilled, which isn't a bad idea anyway to remove NO<sub>x</sub> The result is clean glassware and clean nitric acid, a win-win in my book. This also works wonders for stained stir bars, one nitric acid prep and they're good as new. You could probably put the addition funnel in place of a column, and it would be subject to all of the acid vapors which would hopefully oxidize the sulfur.



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[*] posted on 8-6-2016 at 18:35


Thanks gdflp. That's a pretty cool idea. I think the ptfe stopcock will be up to that. I will have to give it a shot. It sounds a bit more appealing than sploshing around hot xylene.



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[*] posted on 8-6-2016 at 18:42


Quote: Originally posted by diddi  
just hung it on a string in the flood waters j_sum :D

Ha. Missed your comment diddi.
No flood waters up here. I am on the side of a hill 700m above sea level. Floods are a bit rare around here.

(Glad I don't have a multi-zillion mansion on the sand dunes overlooking the ocean though.)




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[*] posted on 8-6-2016 at 23:07


Quote: Originally posted by j_sum1  

(Glad I don't have a multi-zillion mansion on the sand dunes overlooking the ocean though.)

You mean you don't enjoy rebuilding your ridiculously expensive home every few years because it constantly gets hit with storms(on your dime I might add because you can't get insurance)? I thought everyone did:P

[Edited on 6-9-2016 by gdflp]




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[*] posted on 12-6-2016 at 23:39
question on ethyl formate synth


Today I started making a bit of ethyl formate via Fischer esterfication.
Apparently no catalyst is needed for this particular ester.

I refluxed 7ml of >90% formic acid and 6ml of ethanol for 11 hours.

The procedure I'm following says to reflux the mixture for 24 hours, but this seems like overkill to me. I can definitely smell the ethyl formate.

Will my yield be just as good if I stop now at 11 hours?







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[*] posted on 21-6-2016 at 14:42


Let's say we have a gas cylinder that can hold unlimited pressure and doesn't expand (not even a little bit). That cylinder is filled all the way to the top (no space left in it), with liquid gas (CO2 for example). Then we close the valve on the cylinder and start heating it. My question is: would the gas always stay in liquid state, no matter how hot the cylinder becomes? The heat, of course, wants to vaporise the gas, but there's no space and cylinder cannot expand, so how could the pressure build up? Also, if the cylinder couldn't hold unlimited pressure, would its failure still be as violent, if there would be no gas above the liquid phase gas?



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[*] posted on 21-6-2016 at 15:47


Quote: Originally posted by xfusion44  
would the gas always stay in liquid state, no matter how hot the cylinder becomes?


No. If the critical temperature is exceeded, it will be a supercritical fluid, not a liquid.




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[*] posted on 21-6-2016 at 19:50


Quote: Originally posted by gdflp  
I'm not sure how available nitrates are in Aus currently, but one method which I find quite effective to remove organic tars(I've heard it works for sulfur too, haven't tried it) from condensers and flasks is to simply prepare some nitric acid with the contaminated glassware. The hot nitric acid oxidizes anything organic(or sulfur hopefully) to either gaseous(CO<sub>2</sub> and H<sub>2</sub> for organics) or liquid forms. With sulfur you would form either sulfur dioxide or sulfuric acid, neither one is a big deal since they're being used in the preparation anyway so the resulting acid wouldn't be significantly contaminated. Worst case, it needs to be redistilled, which isn't a bad idea anyway to remove NO<sub>x</sub> The result is clean glassware and clean nitric acid, a win-win in my book. This also works wonders for stained stir bars, one nitric acid prep and they're good as new. You could probably put the addition funnel in place of a column, and it would be subject to all of the acid vapors which would hopefully oxidize the sulfur.

This is working beautifully. I am going to have to remember this trick for future grungy glassware.
Thanks.




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[*] posted on 22-6-2016 at 01:00


Quote: Originally posted by Sulaiman  
Would Piranha solution attack the sulphur ?


In my experience, yes.




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[*] posted on 22-6-2016 at 22:13


Can sodium nitrate be used in place of potassium permanganate to oxidize o-xylene to phthalic acid?



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[*] posted on 23-6-2016 at 04:35


Quote: Originally posted by Orenousername  
Can sodium nitrate be used in place of potassium permanganate to oxidize o-xylene to phthalic acid?

Not practically.
Maybe by adding HCl and H2O2 you would get a kind of Aqua Regia that may eventually oxydise (halogenate or nitrosate or both) the side chain depending on the Temperature...but reaction may also happen into the ring...

Afterwards a base treatment would hydrolysate the side chain nitroso or halide...




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[*] posted on 23-6-2016 at 11:10


Quote: Originally posted by Metacelsus  
Quote: Originally posted by xfusion44  
would the gas always stay in liquid state, no matter how hot the cylinder becomes?


No. If the critical temperature is exceeded, it will be a supercritical fluid, not a liquid.


Thanks!




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[*] posted on 23-6-2016 at 11:39


What's the most basic, relatively safe way to make a black-powder-esque pulver from ammonium nitrate without sulfur, and how does one go about making a bang with it? I just need something small for independence day, to tear apart a small cheese block(speaking literally, sharp cheddar cheese)...
Definitely not a kewl, but one needs some fun once and a while. Thanks for any help.




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[*] posted on 23-6-2016 at 15:35


What is the composition of marble? I want to get calcium acetate and calcium chloride, and I thought about using marble, but I cant seem to find a place where it says what marble is composed of, since in some places it says its mainly just CaCO3 (in wich case a recrystalisation should be enough to purify?), and in other places I found it is CaCO3, CaO (no problem so far), SiO2 (wont react with the acid I think, so that leaves me with something to filter, no problem either), Na2CO3 (this is where it would get bad, however where I saw it it says it contains small amounts only, but I dont know how small) and other minor carbonates.
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[*] posted on 23-6-2016 at 17:06


Quote: Originally posted by ficolas  
What is the composition of marble? I want to get calcium acetate and calcium chloride, and I thought about using marble, but I cant seem to find a place where it says what marble is composed of, since in some places it says its mainly just CaCO3 (in wich case a recrystalisation should be enough to purify?), and in other places I found it is CaCO3, CaO (no problem so far), SiO2 (wont react with the acid I think, so that leaves me with something to filter, no problem either), Na2CO3 (this is where it would get bad, however where I saw it it says it contains small amounts only, but I dont know how small) and other minor carbonates.

Reduce the marble into fine powder and wash with hot demi-water then filtrate...the filtrate will contain the Na2CO3, if ever present!

For other minor carbonates...most are unsoluble and hard to separate...MgCO3 (white), CuCO3 (green), FeCO3 (?), Fe2(CO3)3 (orange-red)...

Colour is an indication of pollution by other cations...so I advice you to use white chalk stick used in schools to write on the black board...then at least you have CaCO3 with only traces of white unsoluble carbonates...




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[*] posted on 23-6-2016 at 17:13


Quote: Originally posted by The Volatile Chemist  
What's the most basic, relatively safe way to make a black-powder-esque pulver from ammonium nitrate without sulfur, and how does one go about making a bang with it? I just need something small for independence day, to tear apart a small cheese block(speaking literally, sharp cheddar cheese)...
Definitely not a kewl, but one needs some fun once and a while. Thanks for any help.

NH4NO3/C to make a banger...that will be hard!
Maybe add a little very fine Al powder, but your NH4NO3 needs to be very dry (it is hygroscopic) to get a kind of flash.

Use C black of fume, it is very light and ultrafine for a better homogeneity of the mix.

Then do an ignition test in the open.

Then do a confinement test into a cardboard roll, with a fuse and cardboard stopers...or simpler into the famous triangle banger with a fuse out of a corner (triangle made from a ribbon of paper).

[Edited on 24-6-2016 by PHILOU Zrealone]




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[*] posted on 25-6-2016 at 19:03


I was wondering what salt has the highest melting point? Just looking up a few I could think of, calcium fluoride was the highest at 1418 C/2584 F. Or is there a combination of two salts that might work together that have some high melting point?
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