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kclo4
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Oh! Well, Acetic acid can be dehydrated with sulfuric acid with out decomposing and I think in the lab H2SO4 is easier to use for drying then B2O3.
The reason for this is probably because "ALL" labs will have concentrated sulfuric acid, while they may not stock B2O3. It also probably takes a
significantly longer time for all of the B2O3 to hydrate to form boric acid. Those are my guesses anyways. I wonder how well B2O3 would work with
dehydrating things like nitric acid, sulfuric acid, etc?
Also I believe formic acid is turned into its anhydride; carbon monoxide, when it is mixed with concentrated sulfuric acid. At least according the the
Wikipedia on Carbon monoxide "CO is the anhydride of formic acid. As such it is conveniently produced by the dehydration of formic acid, for example
with sulfuric acid."
So, I guess they had to improvise and use something not so common.
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Panache
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how would one assess what voltage a globe was designed for in the absences of any markings on the globe or box, i have already blown two, quite
spectacular however they are old and rare and i'd rather not fuck them up.
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solo
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I've been looking for a way to separate glacial acetic acid from acetic anhydride.....as it seems regular distillation will not do it....any
suggestions?
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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kclo4
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Just some ideas I'd consider:
a solvent like chloroform or Toluene to dissolve the acetic anhydride and leave the acetic acid?
Does Zinc react with Acetic anhydride? I'm pretty sure it does with Acetic acid.
[Edited on 26-10-2008 by kclo4]
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solo
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| Quote: | Originally posted by kclo4
Just some ideas I'd consider:
a solvent like chloroform or Toluene to dissolve the acetic anhydride and leave the acetic acid?
Does Zinc react with Acetic anhydride? I'm pretty sure it does with Acetic acid.
[Edited on 26-10-2008 by kclo4] |
The idea is to recover the acetic anhydride....I can efford to loose the acetic acid ...so maybe adding zinc to the solution would bind the acetic
(GAA) and leave the acetic anhydride (AA)alone.....will need to check see if zinc doesn't also react with AA....... but you are right about the zinc
and acidic acid
"The zinc would be oxidized, forming hydrogen gas and dissolving the zinc:"
Zn(s) + 2 CH3COOH(aq) ---> 2 CH3COO-(aq) + Zn2+(aq) + H2(g)
.......................source,
http://wiki.answers.com/Q/What_happens_when_zinc_reacts_with...
.....................solo
[Edited on 26-10-2008 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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12AX7
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Ah, but realize the equation specifies aqueous. Acetic solution is plenty ionic to dissolve and react and all, but as it approaches 100% Ac2O, will
it remain so?
Tim
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solo
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Looking at the physical properties of both I found the melting point of acetic acid to be 16.5 C where as the MP of acetic anhydride is -73.1C hence
I will place a sample solution in the freezer and just pour out my acetic anhydride and leave the GAA .....it seems simple enough...I wish I would
refer to the basic properties of compounds in question to figure out their manipulation something I often overlook, .....live and learn......solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Nicodem
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| Quote: | Originally posted by solo
I've been looking for a way to separate glacial acetic acid from acetic anhydride.....as it seems regular distillation will not do it....any
suggestions? |
Why would distillation not work? I'm quite convinced you don't need any fancy distillation columns to separate such two compounds with boiling points
having a difference of 22K. A regular ~50cm column packed with whatever should do. Probably even a simple Vigreux column would work to some extent.
Also, you can not freeze out acetic acid since the mp is depressed in the presence of acetic anhydride (or any other solvent miscible with acetic
acid). Even if part of acetic acid freezes it will not be all of it.
Zinc powder does dissolve in pure acetic acid at the reflux temperature, but it does so very slowly (it takes a few hours). I don't know how it would
behave in the presence of acetic anhydride though. It is quite possible that acetic anhydride gets reduced by zinc.
| Quote: | Originally posted by Panache
how would one assess what voltage a globe was designed for in the absences of any markings on the globe or box, i have already blown two, quite
spectacular however they are old and rare and i'd rather not fuck them up. |
I assume that by "globe" you mean a wolfram lamp or something like that? In such case you could measure the conductivity and estimate/deduce what
power should it nominally be (from the size or function). From the conductivity you could then establish the power if it would not be for the property
of wolfram to have positive thermal conductivity drop. The equation is otherwise:
Sqr(U) = P * R (from P = U^2 / R)
(for example, if R = 100ohm and P = 60W then U = 77V)
But since this would give you a very wrong result due to the before mentioned reason, you should get a correlation factor by doing the same
conductivity measurement with a lamp of known P and U parameters. Of course, first do tests on a lower U than the calculated one.
Assuming you do have an electricity multimeter...
[Edited on 27/10/2008 by Nicodem]
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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Picric-A
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After making trichloromethane from the all too famous Haloform reaction i am left with lots of Sodium acetate whihc i would prefere to keep to make
Methane rather than throw away.
My problem is if there is any exess NaOH in there when i am boiling it down to a powder it would react.
I thoght if i add HCl to the spent mix to convert any remainding NaOH to NaCl then i could seperate the two salts. The only problem is they have
relitivly similar solubility and i am not too good at recrystallisation.
Is there any other way i could get pure sodium acetate out?
thanks!
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kclo4
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| Quote: | | My problem is if there is any excess NaOH in there when i am boiling it down to a powder it would react. |
Are you sure it will decarboxylate that those temperatures?
Think about other possible acids such as sulfuric, etc. The most obvious one here to add would be to just add vinegar!
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Picric-A
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it probably wouldnt decarboxylate but it would give impure acetate...
That is a very good point!
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Formatik
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If you add a mineral acid like HCl to sodium acetate, then it's the stronger acid and will displace the -CH3COO. Acetic acid and NaCl form. The same
thing happens when H2SO4 is added to NaCl.
Adding AcOH sounds like a good suggestion. Add it until the solution is neutral (test with litmus paper).
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Picric-A
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@Formatik- yes it is true that adding HCl to pure sodium acetate will release acetic acid but i am talking about adding it to sodium acetate with NaOH
so it would for the sodium chloride instead of displacing the acid.
And yes i am probably going to use the acetic acid method.
Maybe this could be a method of making formates, formamide easily...
EtOH + CaOCl --> Calcium formate. Calcium formate + H3PO4 --> formic acid
Oh and when you start with acetone and CaOCl it produces calcium acetate... that can be heated to decomp to yield more acetone...
Just a thought.... and i guess impure methylated spirit could be used... and of course you would get plenty of chloroform... 
[Edited on 28-10-2008 by Picric-A]
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bobpage
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What happens when dodecyl hydrogen sulfate is reacted with Ca(OCl)2? Thanks!
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Nicodem
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| Quote: | Originally posted by bobpage
What happens when dodecyl hydrogen sulfate is reacted with Ca(OCl)2? Thanks! |
I assume you are talking about an aqueous solution at room temperature? This must be specified or else the answer can be completely different.
Dodecyl hydrogen sulfate is a relatively strong acid in water solution while HClO is a weak acid (pKa=7.46) thus a proton exchange occurs between the
dodecyl hydrogen sulfate and chlorate(I) anions. This results in formation of HClO in protonation equilibrium (the solution containing also the
solvated ions: Ca2+ cations and dodecyl sulfate anions). What further happens to HClO is a matter of reaction conditions. This can form further
equilibriums depending on the T, concentration, pH and presence of other species. For example, at higher T and/or lower pH the HClO<->Cl2O+H2O
equilibrium becomes important as well as further disproportionation of Cl2O to Cl2, ClO2 and other chlorine oxides. If chloride ions are also present
(for example, by using CaCl(OCl) instead Ca(OCl)2) the HClO gets reduced immediately as it forms to Cl2. The oxidation of dodecyl sulfate anions would
only come into play at higher temperatures in the presence of light trough radical mechanisms (polar mechanisms are unlikely unless the hydrolysis to
dodecyl alcohol happens first).
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Formatik
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| Quote: | Originally posted by Picric-A
@Formatik- yes it is true that adding HCl to pure sodium acetate will release acetic acid but i am talking about adding it to sodium acetate with NaOH
so it would for the sodium chloride instead of displacing the acid. |
Right. As long as you know how much NaOH is in there and how much HCl it needs to be neutral this wouldn't have been a problem.
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Baphomet
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Regarding GAA, has anyone tried gassing Sodium Acetate with dried HCl instead of mixing with aqueous? This would not introduce water, so theoretically
you'd end up with GAA + salt, and distillation would result in pure GAA.. unless some byproducts are formed when using 100% HCl?
\"Who ARE you? You\'re like the drummer from REO Speedwagon - nobody knows who you are\" from \'Employee of the Month\'
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Nicodem
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| Quote: | Originally posted by Baphomet
Regarding GAA, has anyone tried gassing Sodium Acetate with dried HCl instead of mixing with aqueous? This would not introduce water, so theoretically
you'd end up with GAA + salt, and distillation would result in pure GAA.. unless some byproducts are formed when using 100% HCl?
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I guess sodium acetate trihydrate should be able to react with gaseous HCl since once the surface reacts there will form some acetic acid slightly
diluted from hydration water and thus work as reaction medium for further HCl absorption. Probably even anhydrous sodium acetate could do, but making
the anhydrous salt is not so straightforward. The only problem is that once you distil out the liquid you would end up with somewhat diluted (~55%)
acetic acid containing lots with HCl. Perhaps you could concentrate it somewhat by fractionation with a good column, but this would not remove the
HCl. HCl should be removed by adding some sodium acetate, distil again and only then fractionate. I think using H2SO4 or H3PO4 would be more rational
work-wise.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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bobpage
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| Quote: | Originally posted by Nicodem
What further happens to HClO is a matter of reaction conditions. This can form further equilibriums depending on the T, concentration, pH and presence
of other species. For example, at higher T and/or lower pH the HClO<->Cl2O+H2O equilibrium becomes important as well as further
disproportionation of Cl2O to Cl2, ClO2 and other chlorine oxides. If chloride ions are also present (for example, by using CaCl(OCl) instead
Ca(OCl)2) the HClO gets reduced immediately as it forms to Cl2. The oxidation of dodecyl sulfate anions would only come into play at higher
temperatures in the presence of light trough radical mechanisms (polar mechanisms are unlikely unless the hydrolysis to dodecyl alcohol happens
first). |
Thanks, that's the part I was having trouble with!
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Panache
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What distillation columns have people had success with under high vacuum? I'm using a perkin triangle to exclude forerun and temperature control is
normally my method for adjusting the reflux ratio (not the most ideal), however i can add in a cold-finger on top of the column if necessary.
Also dmcs (dimethylchlorosilane, a silalising reagent) treated glass wool appears to be used preferentially in analytical procedures over standard
glass wool, does anyone know why?
[Edited on 30-10-2008 by Panache]
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Klute
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I guess excessive silanol concentration on the glass wool would increase the acidity, which could cause side reactions during sensitive distn. If
completly silylated, the glass would be much less polar, and would have a much weaker influence. To some extent, the silanol groups could also modify
the heat of vaporisation of polar compounds, as the hydrogen links would have to be broken before complete vaporasition, although I think that would
be pretty minimal..
I have always used vigreux columns for vacuum fractionnations, but then again I have never needed very picky seperations, and rarely use very high
vacuum (<0.1 torr) distillations. I prefer column chromatography.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
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Panache
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| Quote: | Originally posted by Klute
I guess excessive silanol concentration on the glass wool would increase the acidity, which could cause side reactions during sensitive distn. If
completly silylated, the glass would be much less polar, and would have a much weaker influence. To some extent, the silanol groups could also modify
the heat of vaporisation of polar compounds, as the hydrogen links would have to be broken before complete vaporasition, although I think that would
be pretty minimal.. |
Well amongst the various bits of information i managed to track down was a one line explanation that for analytical work dcms treated glass had less
'holdup'. This couples well with your theorising. Noticably absent from this forum i have realised are any analytical chemists. guess they're not mad.
| Quote: |
I prefer column chromatography. |
And you are the only one, lol.
Hope your are feeling better.
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Klute
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Funny, everyone at work tells me the same (about the chroamtography)
I did quite some analytical chemistry, nothing too complicated, mostly titrating solutions and mixtures with routine technics. But now I can finally
devote myself to organic chemistry entirely 
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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Picric-A
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Hydroxylamine
Has anyone made this before?
All the synthesis look difficult so i was wondering if anyone has found a way that is suitable to perform in a home lab.
This method looks feasable:
Raschig synthesis: Aqueous ammonium nitrite is reduced by HSO4−/SO2 at 0°C to yield a hydroxylamido-N,N-disulfate anion, which can be
hydrolyzed to give (NH3OH)2SO4.
NH4NO2 + 2SO2 + NH3 + H2O → [NH4]2[N(OH)(OSO2)2]
[NH4]+2[N(OH)(OSO2)2]2− + H2O → [NH4][NH(OH)(OSO2)] + [NH4][HSO4]
2[NH4]+[NH(OH)(OSO2)]− + 2H2O → [NH3(OH)]2[SO4] + [NH4]2[SO4]
Solid NH2OH can be collected by treatment with liquid ammonia. Ammonium sulfate is insoluble in liquid ammonia and is removed by filtration; the
liquid ammonia is evaporated to give the desired product
But the liquid ammonia would be a problem along with having to use Ammonium Nitrite which is dangerously explosive.
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starman
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Formic acid from linseed oil/H2SO4
this reference(18)
States large quantities of formic acid available from this reaction.Bit of a long shot as is ancient history but was wondering if anyone had seen the
original reference or has knowledge of the likely reaction conditions or yeild,particularly %H2SO4 used and formic acid concentration of the
distillate.
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