| Pages:
1
..
6
7
8
9
10
..
20 |
Aqua-regia1
Harmless
Posts: 33
Registered: 9-12-2006
Member Is Offline
Mood: No Mood
|
|
The pinacol rearragement of ethylen glycol doesn't work. I tested it, with several H2SO4 conc. The only one way: dehydratation route. (to difficult
in home lab, therefore expensiv too) But dehydratation is not to very same oxidation.
|
|
|
bbartlog
International Hazard
Posts: 1139
Registered: 27-8-2009
Location: Unmoored in time
Member Is Offline
Mood: No Mood
|
|
I see what you mean about the oxidation states, C2H6O2 versus C2H4O. This is in line with what not_important says about the polyethylene glycol, not
ethylene glycol, being the substance oxidized.
| Quote: | | I suggest that you might show how oxidation of HOCH2CH2OH (C2H6O2) leads to CH3CHO (C2H4O) |
Looks like it can't. Oxidative glycolic cleavage might still be possible, leading to formaldehyde? Anyway, there is a reaction, but I have yet to
distill the solution to try to separate the product(s). An interesting parallel between the Ca(OCl)2 / polyethyene glycol reaction and the one I
observed (6% NaOCl + ethylene glycol) is that both seem to be delayed. They describe a 30 second delay before a fairly sudden hissing and fireball,
while in the case of my mixture nearly five minutes (with shaking of the test tube) passed before the solution rapidly heated up. Could be purely
thermal runaway, I might try a test tube in a beaker of ice water and see what happens. If it still heats suddenly after a similar delay then
something else is going on.
|
|
|
Jimmymajesty
Hazard to Others
Posts: 153
Registered: 9-7-2009
Member Is Offline
Mood: No Mood
|
|
At the production of dioxane small amount of acetal forms which on hydrolysis releases acetladehyde but the acetladehyde reacts with alcohols (glycol
in this case) to form acetals (I think).
It may wort to try to warm ethanol and drip NaOCl solution into it, here the product would be croton aldehyde which can also be used to make stuff
The home performed dehydrogenation is actually feasible, read the attached paper (oxidative dehydrogenation), it is not that difficult to make similar
apparatus at home.
I collected some info on the web regarding acetaldehyde synth by dehydrogenation which I want to share with you not only for informational
purposes! I hope some of you will try out and improve the method, and finally
post the results.
+Catalytic dehydrogentation is a better method to make acetaldehyde due to less side reactions. The copper catalysts perform better than type of
silver and lasts longer.
+Cu-Co-Cr2O3 @ 280-350°C is used industrially (5w%Cobalt+2w%Chrome+93w%Copper), the method of cat. prep. consists of coprecipitation from acetate
salts, and calcining at 550°C max. Then one have to reduce the cat. by hydrogen... I think it is not necessary as the cat. will be reduced under
ethyl alcohol wapors anyway.
+The Cu to Cr mole ratio is optimal at 10:1.
+The yield is affected by the water content of the original water+alcohol mixture the more the alcohol the more ethyl acetate will form.
+Copper from electroplating seemingly do not catalyse dehydrogenation, high surface are is required! (When I read this I stopped electroplating copper
to steel sponge)
I also have the suspicion that the converter (catalyst used to oxidize stull like NxOy and CH into water etc. may be used to make acetladehyde in a
controlled manner.
Attachment: Acetaldehyde production experimental.pdf (179kB)
This file has been downloaded 1558 times
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
I actually made some of this stuff recently. I took a piece of copper pipe and dissolved it in aqua regia. Then I neutralized with a base. You can
use any base, but you can burn away the ammonia salts if you use ammonia, to get a purer CuO. The catalyst works even if sodium salts are present
though. Anyway, once you neutralize, then boil away all the water, and the mixture will turn black. That's CuO, with other salts mixed in. If you
neutralized with ammonia, the mixture will smoke and burn at points as the ammonium nitrate decomposes or oxidizes other components of the mixture.
The next step was putting the CuO into a big test tube. Then I got a two-hole stopper and ran a stainless steel tube to the bottom of the tube, then
ran another one from the top of the tube to a beaker of cold water. I'm sure glass or copper tubes would work fine too, I just happened to have SS on
hand. I boiled alcohol in a bottle connected to the inlet tube, then put an alcohol lamp underneath the test tube of CuO. As vapors entered the test
tube, I could see patches of black CuO turning into pink patches of copper metal. The acetaldehyde vapors smelled like a fruitier, not-as-nasty
version of formaldehyde. As in, it smelled a little like formaldehyde, but didn't burn my eyes and throat.
I realize I didn't control the temperature of the catalyst and thus probably generated some formaldehyde in addition to acetaldehyde, in which case
the fruity smell was probably the acetaldehyde. It did work, although I have to add that this stuff has too low of a boiling point to be able to
condense it efficiently or have it around in a pure state. You pretty much have to dissolve it in a liquid.
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
Just discovered two more ways of making acetaldehyde. First is reduction of acetonitrile with tin(II) chloride in hydrochloric acid. This turns
tin(II) chloride to tin(IV) chloride and acetonitrile to an iminium salt which is hydrolyzed to acetaldehyde. Look up the "Stephen aldehyde
synthesis" for this one.
The other method is the ozonolysis of propylene. Those yellow torch tanks you find at the hardware store are mostly propylene, and you can
CAREFULLY!!! bubble them into a polar solvent (preferably a nonflammable one) to dissolve it, then bubble ozone in to split it into acetaldehyde and
formaldehyde. You need to do it in a reducing environment to get these products though. Also, the gas from these tanks typically has an odorant
added to it, which will give it that sulfury gas smell, but that is at a really low concentration and shouldn't affect the chemical properties,
although it would make it harder to tell by smell what your products are.
|
|
|
Fleaker
International Hazard
Posts: 1252
Registered: 19-6-2005
Member Is Offline
Mood: nucleophilic
|
|
The sulfury gas smell would be rendered odourless by ozone! Not that my idea of fun is making ozone and using it as an oxidiser!
Interesting on the stannous chloride side. Please post more information/mechanism and references. I love my tube furnace reactions, but this method
sounds VERY intriguing.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
Quote: Originally posted by Fleaker  | | The sulfury gas smell would be rendered odourless by ozone! Not that my idea of fun is making ozone and using it as an oxidiser!
|
You're right, although the gas is detectable even at really low concentrations so you'd probably still smell it if you didn't get it all. I have an
ozone generator that I use to deodorize/sanitize stuff on occasion so I've already got that covered. On the bright side, the odorants tend to be
methyl/ethyl sulfides, which are used as reducing agents in ozonolysis anyway.
| Quote: | | Interesting on the stannous chloride side. Please post more information/mechanism and references. I love my tube furnace reactions, but this method
sounds VERY intriguing. |
Apparently it requires tin(II) chloride dissolved in ether, then saturated with hydrogen chloride. Check out the attachment.
Yet another synthesis appears to be the destructive distillation of calcium formate and calcium acetate, which would also produce low yields and a lot
of acetone, CO2, and hydrogen, but at least it's really straightforward.
Attachment: stephen aldehyde synthesis.pdf (254kB)
This file has been downloaded 1825 times
[Edited on 4/1/10 by Melgar]
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
Also, tin is pretty easily obtained from lead-free solder, since I have yet to see a lead-free solder that is less than 95% tin. However, the
hardware store muriatic acid I have has quite a bit of iron dissolved in it, (visible by the yellow color) and this immediately plated onto the tin
solder and seemed to prevent it from dissolving very much. Still, this seems to be a good way to get the iron out of my muriatic acid, if nothing
else.
|
|
|
Jimmymajesty
Hazard to Others
Posts: 153
Registered: 9-7-2009
Member Is Offline
Mood: No Mood
|
|
Nice try! But I am afraid you only made small amount of the required stuff
I am going to co-precipitate cobalt and copper hydroxydes, pour the slurry to MgO, activated carbon, or alumina, and heat it to 500°C for some hours.
Another way would be the one suggested by Melgar, that is to dissolve the hydrohydes in aq. ammonia, pour the solution to something porous and inert,
vacuum treat the stuff then heat it then crush it in a mortar to granules. I can see one problem with MgO carrier, namely it absorbs water so when
alcohol wapor is passed ower it it would become a gel and loose catalytic properties, so my preferred mat. would be activated carbon particles, they
have a lot of surface and can not be dissolved in alcohol ofc. Or rather! the insulation from kanthal heating filaments, they are made of 96w% Al2O3,
being totally heat and corrosion resistant.
Acetonitrile method? I also know some exotic procedure during which acetaldehyde is liberated, some diazotization e.g. but i dunno if you could make
decent quantity of acetaldehyde by that..
Propylene ozonolysis in home lab? I can only see countless problems. e.g.
generation of ozone in useful quantities is a PITA. BTW the smell is probably from ethyl mercaptan which is oxidized by ozone to SO2 then SO3 if you
use excess of ozone, I also have a suspicion that sulfur containing material are more prone to oxidation that propylene, also IIRC
propylene+ozone=explosion unless low temps are used.
I am goint to try out the above posted catalysts asap and post the results.. that means months unfortunately.
Oh! When I made acetaldehyde with my previous setup by catalytic dehydrogenation, the smell was rather unpleasant and spicy when you took a nosefull
of it, it means that a lot of side reaction occurred?!.. The themp of the condenser was not controlled, and the temp. control in the reaction zone was
crude too.. I have to overcome these problems!
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
My ozone generator can do 600 mg an hour in air, meaning it can make a little less acetaldehyde than that. The formaldehyde is a bonus if you can use
it. Since it uses a 1/3 duty cycle on its highest setting, that's like a gram and a half overnight. Also, in an insulated container with lots of ice
and calcium chloride, chances of explosions are minimal if your solvent isn't flammable. CH2Cl2 is used a lot for this reason, although I personally
have yet to try it. Still looking for a decent reducing agent. Also, I'm pretty sure ozone attacks double bonds preferentially, then sulfur
compounds after that. Oh, and mercaptans are oxidized to different things depending on the oxidizer, but rarely to SO2 or SO3.
Actually, the acetonitrile method seems like it would be the most likely to give good, consistent yields, since the iminium salt precipitates out and
can be filtered from the ether. I'll probably try the destructive distillation route too since I have the formic acid, acetic acid, calcium chloride,
and sodium hydroxide that are required.
Activated carbon will burn if there's oxygen present and it's hot enough, so there's a good chance it could reduce your copper oxide to copper metal
and leave as CO2. Aluminum oxide is available as sandblasting grit, and that seems to be a good catalyst substrate. It's used a lot in industry
anyway. Plus it's white, so you'd be able to distinguish your catalyst from the substrate if nothing else. Even silica (sand) seems like it could
do the job well enough.
|
|
|
hissingnoise
International Hazard
Posts: 3940
Registered: 26-12-2002
Member Is Offline
Mood: Pulverulescent!
|
|
| Quote: | | Actually, the acetonitrile method seems like it would be the most likely to give good, consistent yields, since the iminium salt precipitates out and
can be filtered from the ether. I'll probably try the destructive distillation route too since I have the formic acid, acetic acid, calcium chloride,
and sodium hydroxide that are required. |
Hydration of acetylene seems simpler, requiring only C2H2, H2SO4 and Hg.
|
|
|
Jimmymajesty
Hazard to Others
Posts: 153
Registered: 9-7-2009
Member Is Offline
Mood: No Mood
|
|
A gram and a half overnight is not that much unfortunately.. but try it and post the results please! I am working in an olefin plant so pure propylene
is not that hard to get
My ozone generator are made of a test tube with Al foil wrapped around it and a tiny wire in it, I drive the generator with a flyback transformer from
an old television... without the current rectifier part. But a germicide lamp would also do the job.
I dont have such things like DCM or acetonitrile, and based on a quick search, acetonitrile is not that easy to make at home..
I would prefer dehydrogenation rather than catalytic oxidation, but if I were to apply catalytic oxidation as a last resort. I would make silver
mirror to a glass tube then stuff the tube with silver sponge made of fusing AgCl and Na2CO3. To cut it short I try the activated carbon first (large
surface area) then Al2O3 insulation rings.
The idea which was discussed upthread is more feasible than the formiate etc methods. Namely you melt tartaric acid with KHSO4 to get pyruvic acid,
and that readily decomposes to acetaldehyde however I am not sure about the conditions and temps that the last part requires. The first part of the
synth: tartaric+KHSO4 is on org synth webpage. BTW the tartaric acid is more OTC here than sodium hydroxide that is a big plus!
|
|
|
Lambda-Eyde
National Hazard
Posts: 857
Registered: 20-11-2008
Location: Norway
Member Is Offline
Mood: Cleaved
|
|
| Quote: Originally posted by Melgar | | However, the hardware store muriatic acid I have has quite a bit of iron dissolved in it, (visible by the yellow color) and this immediately plated
onto the tin solder and seemed to prevent it from dissolving very much. Still, this seems to be a good way to get the iron out of my muriatic acid,
if nothing else. |
Let me see if I got this right - you just leave a piece of soldering tin in the hydrochloric acid, and the yellow color dissappears? I'm not pleased
with the coloring of my acid, and I don't have reagent grade at the moment.
Some tin will dissolve anyways, so I think distillation of 20% HCl would be the best way to go if I want it somewhat metal-free.
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
Well, I tried putting some solder in my HCl again today, and the iron didn't come out as quickly as I thought it would, although it did come out
eventually. I think the yellow iron chloride just gets replaced by colorless tin chloride. I'm not sure how much success would come from distilling
HCl, since it's a gas dissolved in water. My plan was to combine CaCl2 and H2SO4 to form HCl gas, then bubble that into distilled water.
Unfortunately, that reaction got a little out of hand and sulfuric acid got spilled all over the place. I'll try that again with more precautions
once my workbench is de-acidified.
To make acetaldehyde via destructive distillation you need hydrated lime, formic acid, and acetic acid. Hydrated lime is dirt cheap at the hardware
store but you can make it from NaOH and CaCl2 if you just need a little and don't feel like making a special trip. The reaction seems as though it
would produce CO2, formaldehyde, acetone, and acetaldehyde. Probably more acetaldehyde than anything else, although I hear destructive distillation
yields suck anyway.
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
| Quote: Originally posted by Jimmymajesty | | I dont have such things like DCM or acetonitrile, and based on a quick search, acetonitrile is not that easy to make at home.. |
DCM is actually really easy to get. Just go to the solvent section of your local hardware store (our favorite section!) and find the paint strippers.
They all have warning labels on them saying "CAUTION, FLAMMABLE!", "CAUTION, POISON!" or both. Look for the ones that don't say "flammable". Since
DCM is practically the only nonflammable solvent in this aisle, any paint stripper that doesn't seem to be flammable is probably mostly DCM. Also,
look for the sprayable stuff, as in, the stuff that doesn't come as a gooey paste. It's a lot easier to distill.
Acetonitrile isn't that cheap at $50 a liter or so, but every so often a reaction calls for it as a solvent, so I have a bottle on hand. Supposedly,
a recent shortage drove prices up and they aren't normally that high.
|
|
|
DJF90
International Hazard
Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline
Mood: No Mood
|
|
Paint stripper is generally (at least in the UK) a blend of dichloromethane and methanol, so should still bear the "flammable" warning... you'll just
have to read the label (this applies to wherever you are; theres nothing worse than buying something, attempting extraction and finding the desired
material is not a component).
|
|
|
Lambda-Eyde
National Hazard
Posts: 857
Registered: 20-11-2008
Location: Norway
Member Is Offline
Mood: Cleaved
|
|
| Quote: Originally posted by Melgar | | Well, I tried putting some solder in my HCl again today, and the iron didn't come out as quickly as I thought it would, although it did come out
eventually. I think the yellow iron chloride just gets replaced by colorless tin chloride. I'm not sure how much success would come from distilling
HCl, since it's a gas dissolved in water. |
I have distilled HCl with success, but it's only the 20,2 % azeotrope that comes over. That is, theoretically, as I haven't quantitatively measured
it.
The 30 % acid first fumes like crazy until it reaches the azeotropic point, when it starts to distill over. Interestingly, the azeotropic
concentration has a much higher vapor pressure than the 30 % concentation - Just like the distillate I obtained. I don't like the idea of using
precious (at least precious to me) H<sub>2</sub>SO<sub>4</sub> to make HCl. There is an alternative way which involves using
CaCl<sub>2</sub> as a drying agent to extract the water from aqueous HCl, making gaseous HCl.
Bubbling HCl gas made with this method through the distilled 20 % acid is a much more attractive method for me than using sulfuric acid. Alternatively
I can wait a while and buy a liter from Chiron or Fisher Scientific...
But hey, this is going very off-topic. Sorry! 
|
|
|
JohnWW
International Hazard
Posts: 2849
Registered: 27-7-2004
Location: New Zealand
Member Is Offline
Mood: No Mood
|
|
Paint stripper containing CH2Cl2 poses a hazard well beyond the fact that it is inflammable. When it burns, the major product would be phosgene,
COCl2, which is deadly poisonous, and which was used, along with "mustard gas", by the Germans in WW1. Besides, volatile chlorocarbons are also known
as liver toxins, if ingested or inhaled in any large quantity.
|
|
|
manimal
Hazard to Others
Posts: 180
Registered: 15-1-2008
Member Is Offline
Mood: ain't even mad
|
|
| Quote: Originally posted by Melgar | | Just discovered two more ways of making acetaldehyde. First is reduction of acetonitrile with tin(II) chloride in hydrochloric acid. This turns
tin(II) chloride to tin(IV) chloride and acetonitrile to an iminium salt which is hydrolyzed to acetaldehyde. Look up the "Stephen aldehyde
synthesis" for this one. |
I'm pretty sure the Stephen aldehyde synthesis is done anhydrously with dry HCl gas being piped in.
The H2SO4 dehydration/rearrangement works, but only under pressure. At atmospheric pressures, the glycol gets etherified and escapes the reaction.
There is a US patent somewhere on H2SO4 dehydration of simple glycols in a pressurized still.
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
| Quote: Originally posted by Lambda-Eyde |
I have distilled HCl with success, but it's only the 20,2 % azeotrope that comes over. That is, theoretically, as I haven't quantitatively measured
it.
The 30 % acid first fumes like crazy until it reaches the azeotropic point, when it starts to distill over. Interestingly, the azeotropic
concentration has a much higher vapor pressure than the 30 % concentation - Just like the distillate I obtained. I don't like the idea of using
precious (at least precious to me) H<sub>2</sub>SO<sub>4</sub> to make HCl. There is an alternative way which involves using
CaCl<sub>2</sub> as a drying agent to extract the water from aqueous HCl, making gaseous HCl.
Bubbling HCl gas made with this method through the distilled 20 % acid is a much more attractive method for me than using sulfuric acid. Alternatively
I can wait a while and buy a liter from Chiron or Fisher Scientific...
But hey, this is going very off-topic. Sorry! |
Eh, if I use cheap-ass buffered H2SO4 drain cleaner and CaCl2 driveway ice melter, it's not that expensive. I kind of like that reaction because it
converts all the Cl and H ions to HCl and it goes slow enough that you don't get a room full of HCl vapors instead of getting them in solution. The
CaCl2 + muriatic one is good too, although I don't think it's as efficient and it seems like you have to use a lot of CaCl2. But that stuff is cheap
so who cares.
| Quote: | | Paint stripper is generally (at least in the UK) a blend of dichloromethane and methanol, so should still bear the "flammable" warning... you'll just
have to read the label (this applies to wherever you are; theres nothing worse than buying something, attempting extraction and finding the desired
material is not a component). |
Yeah, that's true for the paint stripper here too, but I figured the methanol level must be comparatively low because the containers weren't marked as
flammable. And yeah, reading the labels is always key.
| Quote: | | I'm pretty sure the Stephen aldehyde synthesis is done anhydrously with dry HCl gas being piped in. |
Yeah, I post a more detailed explanation a few posts down.
|
|
|
Jimmymajesty
Hazard to Others
Posts: 153
Registered: 9-7-2009
Member Is Offline
Mood: No Mood
|
|
Hi folks!
If I were to make gaseous HCl I would pour 20w% HCl sol. into conc H2SO4 and distill off the gas, then lead it through a H2SO4 wash bottle to absorb
traces of H2O, the H2SO4 then could be regenerated by heating.
I would not even attempt the CaCl2+H2SO4 method based on the Ca(NO3)2+H2SO4 experience, you will make an awfull mess for sure!
My problem is acetonitrile, I was a trainee once in an isocianate plant, acetonitrile was used as a solvent for HPLC uses, but I forgot to steal
some..
I could buy DCM but it is expensive so I won't! BTW DCM based solvents is being drawn out from hypermarkets, at least in my country. I could buy it a
year before or so, the methanol content was 10w%, but also there was a slurry layer on the bottom which was IIRC some kind of pine resin which during
distillation solidifies maybe polyemrizes into the flask!
Melgar! you have all the necessary chems to give the procedure a try! so it is your turn!
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
If you only want a small amount of acetaldehyde you can just try with the Kornblum oxidation of ethyl bromide. Ethyl bromide can be made from ethanol,
KBr/NaBr/NH4Br and H2SO4 (there are examples on the forum). Ethyl bromide reacts with DMSO fairly rapidly, so all you need to do is stir a solution of
ethyl bromide and NaHCO3 in DMSO for a day at room temperature and then distil out acetaldehyde (mind the condenser cooling!). The Kornblum oxidation
generally requires heating at 80-100°C for most alkyl halides, which is not an option for the volatile EtBr, but I think its reaction with DMSO to
give the intermediate S-ethoxysulfonium ion, occurs at lower temperatures already.
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
| Quote: Originally posted by Jimmymajesty | Hi folks!
If I were to make gaseous HCl I would pour 20w% HCl sol. into conc H2SO4 and distill off the gas, then lead it through a H2SO4 wash bottle to absorb
traces of H2O, the H2SO4 then could be regenerated by heating.
I would not even attempt the CaCl2+H2SO4 method based on the Ca(NO3)2+H2SO4 experience, you will make an awfull mess for sure! |
Weird, I've done both reactions and they never gave me much trouble. The end result is CaSO4, aka gypsum. But it's gypsum as a powder which is
easily washed out with water. Granted, the H2SO4 is a loss, but I found a pretty cheap local source ($10 a liter) so it's not a major problem.
I think heating the H2SO4/water/HCl mixture would give off a lot of fumes. But I guess you could send the vapors through any basic solution to
minimize smells.
| Quote: | My problem is acetonitrile, I was a trainee once in an isocianate plant, acetonitrile was used as a solvent for HPLC uses, but I forgot to steal
some..
I could buy DCM but it is expensive so I won't! BTW DCM based solvents is being drawn out from hypermarkets, at least in my country. I could buy it a
year before or so, the methanol content was 10w%, but also there was a slurry layer on the bottom which was IIRC some kind of pine resin which during
distillation solidifies maybe polyemrizes into the flask!
Melgar! you have all the necessary chems to give the procedure a try! so it is your turn! |
My problem is lack of ether. I have some, but it's definitely not very clean or dry, and probably is contaminated with water and ethanol. I'm trying
to dry it using an aluminum amalgam, since that should theoretically work almost as well as sodium or potassium. It'd be nice if I didn't have to
make it myself from Everclear.
As for the other two reactions, they both produce formaldehyde, and I want to try and make formaldehyde-free acetaldehyde so I can make sure I
recognize the smell.
Lately I've been trying to make my own ethanol from distiller's yeast and sugar water. It's been a little tricky initially, especially hooking my
distillation apparatus up to a practical boiler device. However, I did notice something VERY interesting. When it's hooked up, the first bit to come
over smells identical to what I smelled when I ran ethanol vapors over copper oxide. No formaldehyde smell either. This makes sense, because these
buckets have been sitting around for at least a month beyond when they were ready, as I've been trying to make time to distill them. They weren't
airtight, so it seems plausible that oxidizing bacteria have gotten in and started to oxidize the ethanol to acetaldehyde. The next step would be
acetic acid, but that has a higher boiling point and they probably haven't gotten there yet. If this really is acetaldehyde, this would be a really
easy way to make it, although there would have to be a way to get it out of the ethanol/water/acetic acid that it's dissolved in.
By the way, the smell that I think is acetaldehyde is a sweet, fruity smell that smells vaguely like overripe plums. I'm still not sure how to get it
out. Making an imine perhaps? But then, how to isolate the imine? And would it be especially temperature-sensitive?
[Edited on 4/6/10 by Melgar]
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
Just did the acetonitrile reaction in ether, but even though it was successful, it was kind of a letdown to do all that work for a test tube half full
of something that smelled like overripe plums. But anyway, I think that's the last time I'm going to do that reaction. I can make liters of the
stuff by fermenting sugar in buckets and letting it oxidize beyond the initial fermentation. Plus, I learned that sodium bisulfite will react with
acetaldehyde to form a precipitate. The precipitate can be made to release acetaldehyde by treating it with a base. You can probably get sodium
bisulfite from brewing stores, but you can also make it yourself. I did. Basically, you have to bubble SO2 through an aqueous solution of Na2CO3. I
got the SO2 by burning sulfur in a jar and having an aquarium pump pumping in fresh air, while the fumes were going out an exhaust pipe and into the
Na2CO3 flask. It was a fairly cool and very easy reaction, while not being all that dangerous either.
|
|
|
Jimmymajesty
Hazard to Others
Posts: 153
Registered: 9-7-2009
Member Is Offline
Mood: No Mood
|
|
The case is the same with DMSO.. unfortunately i do not have any.
I think the best method would be ethanol dehydrogenation or catalytic oxidation, as there wold be no side products, (maybe some ethyl acetate and
acetic acid which can be fractionated and used for something else). If croton aldehyde formed due to harsh reaction conditions it could still be used
for making penataeritrithol.
I am not familiar with fermentation processes, but Melgar promised to try it out and post the results as his next experiment so I leave it for him Be careful with yeast because it can easily overoxidize your desired product to
acetic acid, and it will certinly do so in that conditions.
Yes saturated NaHSO3 (best if freshly made because it has the tendency to absorb oxygen) solution and acetaldehyde forms a crystalline compound which
can be decomposed by adding a strong acid, the case is the same with cc NH3 solution, you can make aldehyde ammonia then release the aldehyde by
adding H2SO4.
BTW in wine shops potassium metabisulphite can be bought which formula is K2S2O5, maybe you can convert it to KHSO3 by adding KOH I am not sure of
that, I am also uncertain if K2S2O5 forms precipitate with aldehydes.
When pure sulphur is burnt SO3 forms too which makes a white smoke with atmospheric moisture, so your sulphite will not be purer than 92% of the
theoretical at saturation (IIRC).
Oh! Have you identified the aldehyde by silver mirror test?
|
|
|
| Pages:
1
..
6
7
8
9
10
..
20 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
