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confused
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[*] posted on 11-5-2013 at 10:28


Quote: Originally posted by elementcollector1  
Apparently, anything will work for filtration (except for a hand pump), even vacuum cleaners. For distillation, I would honestly recommend an aspirator - no suckback or chemical traps necessary for a good plastic one.


yes, but my workarea/lab is not near a water source and rigging up my waterpump with an aspirator while maintaining water flow through the condenser while doing a distillaion isn't really feasible at the moment.

so, how powerful would a standard lab vacuum pump usually be?
and while we're at it, what unit do you guys use to calculate negative presure(vacuum)? Pa, bar, mmHg, psi or atm?
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[*] posted on 15-5-2013 at 06:17


Would candle wax dissolve in methanol if it were melted or would it tend to separate?
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confused
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[*] posted on 15-5-2013 at 06:54


paraffin wax is miscible in methanol,
however, the melting point of paraffin wax is really quite close to the boiling point of methanol, so you would have to continously add more methanol to prevent all of it from evapourating/boiling away unless you use a reflux setup

not to mention that methanol vapours are flamable, so, i highly reccomend using somthing other than an open flame or anything that could possibly create a spark while doing it.

out of curiosity, what would you want to do that for?
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[*] posted on 15-5-2013 at 08:34


Quote: Originally posted by confused  
paraffin wax is miscible in methanol,
however, the melting point of paraffin wax is really quite close to the boiling point of methanol, so you would have to continously add more methanol to prevent all of it from evapourating/boiling away unless you use a reflux setup

Are you sure? I seem to recall finding that heptane didn't mix with methanol as well as I expected, and paraffin would be even less likely to dissolve in it.

The Merck Index says that paraffin is insoluble in water and alcohol.




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[*] posted on 15-5-2013 at 13:43


Quote: Originally posted by confused  
paraffin wax is miscible in methanol,
however, the melting point of paraffin wax is really quite close to the boiling point of methanol, so you would have to continously add more methanol to prevent all of it from evapourating/boiling away unless you use a reflux setup

not to mention that methanol vapours are flamable, so, i highly reccomend using somthing other than an open flame or anything that could possibly create a spark while doing it.

out of curiosity, what would you want to do that for?


I was pondering the possibility of using paraffin as fuel but initially starting the engine with methanol. Methanol has some good qualities but the boiling point so low that perhaps transitioning to wax would work better in some cases. For my purposes, gasoline ruins the fuel/air ratio and becomes too rich, often so much so you can't even get the flame front to chase down into the combustion chamber. Paraffin wouldn't start evaporating until heated to a fairly "high" temperature. I'm trying to keep it simple, the engine feeding off an evaporating pool of fuel in the bottom of the combustion chamber.
I've tried other fuels and some blends - nitromethane, acetone, ether, ethanol, isopropyl, and gasoline.
The store I was at today had nitro for $30.00 a half gallon. It's kind of expensive and doesn't really work for what I do.
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confused
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[*] posted on 15-5-2013 at 16:11


Quote: Originally posted by DraconicAcid  
Quote: Originally posted by confused  
paraffin wax is miscible in methanol,
however, the melting point of paraffin wax is really quite close to the boiling point of methanol, so you would have to continously add more methanol to prevent all of it from evapourating/boiling away unless you use a reflux setup

Are you sure? I seem to recall finding that heptane didn't mix with methanol as well as I expected, and paraffin would be even less likely to dissolve in it.

The Merck Index says that paraffin is insoluble in water and alcohol.


...my bad, i was going by the assumption that organic compounds dissolve in organic solvents :(
but i just checked the polarity of paraffin wax and methanol. Paraffin wax is non-polar while methanol is polar
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[*] posted on 15-5-2013 at 19:20


Some tidbit pertaining to some possible exceptions of solubility of "wax compounds" and alcohols.
"Ethanol has been used advantageously
as a co-solvent to modify the polarity of pressurized
carbon dioxide or water for the extraction of natural products
[6, 7]. More recently the application of hot ethanol to recover
waxes from flax fiber processing waste containing cuticle tissue
was also demonstrated [8]. These results motivated the
current investigation of the temperature-dependent solubility of fatty esters in ethanol and the possibility of use in biomassto-
ethanol conversion."
Temperature-dependent solubility of wax compounds in ethanol
http://naldc.nal.usda.gov/download/44460/PDF
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[*] posted on 15-5-2013 at 22:07
electrolytic activation of iron filings


Randolph Carter who I believe knows what he does speaks in this post of electrolytic preparation of purchased iron filings, which were used in a nitropropene reduction to the correspondending ketone.

Now the only "preparation" or activation of iron for such reactions I know of is the short wash in diluted HCl....
But the electrolytic sounds interesting and promising.
If I only had a clue how to do it.

Anybody in the know willing to help me out?

regards
/ORG
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[*] posted on 16-5-2013 at 08:47


Quote: Originally posted by Morgan  
Some tidbit pertaining to some possible exceptions of solubility of "wax compounds" and alcohols.
"Ethanol has been used advantageously
as a co-solvent to modify the polarity of pressurized
carbon dioxide or water for the extraction of natural products
[6, 7]. More recently the application of hot ethanol to recover
waxes from flax fiber processing waste containing cuticle tissue
was also demonstrated [8]. These results motivated the
current investigation of the temperature-dependent solubility of fatty esters in ethanol and the possibility of use in biomassto-
ethanol conversion."
Temperature-dependent solubility of wax compounds in ethanol
http://naldc.nal.usda.gov/download/44460/PDF


Interesting paper. It shows that at 45oC, the solubility of these waxes (all of them esters, not the paraffin sort) is on the order of 0.05 g/L. That's not very soluble at all.




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Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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[*] posted on 16-5-2013 at 23:24


Hi, is there any way to make or extract sodium dodecyl sulfate from commonly avalible products
without oleum, chlrosulfuric acid or SO3?

I need some for preparation of some buffer solutions for microbiology
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[*] posted on 22-5-2013 at 15:29


Is there any known method to turn an enamine to an enol ether? I found only references to turn them back to ketones... But I would need to get an enol ether and not get back the oxo.

Thanks!
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[*] posted on 24-5-2013 at 13:23


I would like to know how to add a methoxy group ....starting with,



.....and end up with this,







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[*] posted on 27-5-2013 at 17:41


I have a question regarding the use of MMO anodes in acidic conditions. I've been doing some work with chlorinating organic compounds using chlorine generated in situ via electrolysis, but to avoid the haloform reaction I need acidic conditions. I have been using graphite anodes, but they corrode rapidly into annoying black sludge. Will a MMO anode stand up to acidic conditions (specifically HCl)?



As below, so above.
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[*] posted on 27-5-2013 at 19:16


If it stands up to Cl2, I'd be willing to wager the same for HCl. Mind you, platinum or platinum-plated is where it's at.



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[*] posted on 28-5-2013 at 10:51


OK, I'm trying it now. I hope you're right!

By the way, where can you get platinum electrodes? Seems expensive.

[Edited on 28-5-2013 by Cheddite Cheese]




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[*] posted on 28-5-2013 at 13:36


Quote: Originally posted by confused  
Quote: Originally posted by elementcollector1  
Apparently, anything will work for filtration (except for a hand pump), even vacuum cleaners. For distillation, I would honestly recommend an aspirator - no suckback or chemical traps necessary for a good plastic one.


yes, but my workarea/lab is not near a water source and rigging up my waterpump with an aspirator while maintaining water flow through the condenser while doing a distillaion isn't really feasible at the moment.

so, how powerful would a standard lab vacuum pump usually be?
and while we're at it, what unit do you guys use to calculate negative presure(vacuum)? Pa, bar, mmHg, psi or atm?


In this case you want a chemical resistant diaphragm pump with PTFE heads, it is not about power but resistance and tolerance to vapors in this case. In the end it solely depends on the size of your briefcase.
There are heaps of vacuum related threads here offering all answers you might look for, pls search.

We at SCM, well at the least the real ones, measure vacuum in "s**k!" a unit which is directly derived from the english weight "stone". The detailed information is in the "over 18" section of SCM.

regards
/ORG
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[*] posted on 31-5-2013 at 19:39


http://www.britannica.com/EBchecked/topic/17932/aluminosilic...

"Aluminosilicate glasses find applications similar to those of borosilicates, but the former can stand higher operating temperatures; glasses with relatively high alumina contents and no boric oxide are exceptionally resistant to alkalies. "

That sounds smashing, baby. Has anybody heard of it used; or why isn't it common? Just hard to melt, or another flaw?


Solo: There was a synthesis of 3-something-pyr, nicotine maybe, wherein first was brominated, then chlorinated, bromine removed. It's ugly but what else? Demethylenation? Best luck creating a special enzyme, actually, it's a long shot but some kind of hydroxylase might work!! A cactus enzyme eh? It works fa them.

[Edited on 1-6-2013 by halogen]

[Edited on 1-6-2013 by halogen]
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shocked.gif posted on 1-6-2013 at 17:58


Gorilla Glass?
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[*] posted on 1-6-2013 at 21:02


For labware though. I found some stuff: centrifuge tubes, raw tubing, it's apparently helium proof. It's not common, it can't be that much more difficult to form, looking at brittanica's mp diagram. I'd thought chemists would appreciate alkali&heat resistance.

And - this is the answer! :

"Aluminosilicate glass is very difficult to work with because it is very prone to reboil. That is, while bringing it a working temperature, the glass develops bubbles over the surface that are impossible to remove. One other challenge with aluminosilicate glass, which is different from other glasses, is that you can't clean itwith hydrofluoric acid (see Sec. 4.1.10). If attempted, it will cause the surface to develop a translucent sheen that is also impossible to remove. It is safe (for the glass) to clean the surface with nitric acid"

From http://www.scribd.com/doc/79709916/7/Different-Types-of-Glas...

[Edited on 2-6-2013 by halogen]
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[*] posted on 4-6-2013 at 12:06


In a water pump for a condenser/distillation setup, what would be the ideal rate of flow (in GPH) for the pump to have?



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[*] posted on 4-6-2013 at 12:57


Quote: Originally posted by Variscite  
In a water pump for a condenser/distillation setup, what would be the ideal rate of flow (in GPH) for the pump to have?


I don't think it really matters what the GPH is as long as there is a constant flow and the reservoir is big enough to allow for a constant temperature throughout the distillation.
I use a salvaged desktop fountain pump, it is very small, but adequate for normal distillations. However, when I setup for refluxing I have to run two pumps together to get constant vertical flow, or elevate the reservoir.




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[*] posted on 5-6-2013 at 11:28


Quote: Originally posted by confused  
Hi, is there any way to make or extract sodium dodecyl sulfate from commonly avalible products
without oleum, chlrosulfuric acid or SO3?

I need some for preparation of some buffer solutions for microbiology


Many shampoos and detergents are nearly pure sodium dodecyl sulfate solutions already. If you find a shampoo without dyes or frangrance, it might be good enough for simple biology work. Just look at the labels.
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[*] posted on 5-6-2013 at 20:12


Quick question about HCl

I recently purchased some toilet cleaner stating to be 10% HCl, it sounded like a liquid in the bottle though after checking it is more of a disgusting gel, is there anyway to extract the HCl, perhaps thermal decomposition and re-absorption in water?

Thanks for any answers.
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[*] posted on 6-6-2013 at 18:39


When chlorinating an amino alcohol (tertiary amine, secondary alcohol) with ZnCl2 and HCl, would complexes ruin the party?
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[*] posted on 7-6-2013 at 05:38


Does plastic destroy chlorine dioxide, ie can I use a plastic testtube when making the gas or do I have to stick with glass (worried about explosions + shrapnel)
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