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solo
International Hazard
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/re: synthesis of Acetadehyde
primo pyro.........some references for your claim, on the use of regular antifreeze and H2SO4 to make acetaldehyde I checked rhodium and althoudh I
found th said reaction (Pinacol Rearrangement.) , I guess I just didn't see it clearly or specificallyfor (ethylene glycol) as you stated on your
post. Since I have to make everything this is of some interest.
Noted also something about Zinc , HCl reducing the carboxylic acid to an aldehyde , something said by someone else , not you , but do you know or
have you heard of such a procedure , I myself have been looking both in March's and literature about such reactions but have had no sucess.
thanks, Saludos , from Latin America
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10fingers
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Making acetaldehyde from ethylene glycol sounds interesting. I tried a little experimenting with it though and got nothing. I tried various
concentrations of H2SO4 and different temps and it did not seem to react in any way at all.
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madscientist
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I recently attempted to dehydrogenate ethanol to yield acetaldehyde. I boiled 100mL of ethanol (denatured alcohol) and passed the vapors through a
copper tube that was being heated by a propane burner. Initially, I wasn't cooling the condensation tube effectively enough, so only a small amount of
non-dehydrogenated ethanol was being condensed, and resulting in my backyard being pumped full of a plasticy-smelling vapor, which I assume was
acetaldehyde. I did manage to quickly get it cold. I ended up with around 60mL of liquid. I didn't have the chance to try to analyze it - I hopefully
will do so soon.
I weep at the sight of flaming acetic anhydride.
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10fingers
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I tried the catalytic dehydrogenation of ethanal awhile back. I got a little bit of acetaldehyde but I was using a huge amount of ethanol. You also
need to add air or oxygen to the ethanol before the catalyst. I think part of the problem with my system was that it did not have an efficient
condenser for the acetaldehyde vapors. Acetaldehyde boils at 21* C so you really need to cool it down or most of it will be lost.
I saw a patent where they ran the vapors into cold water to capture the acetaldehyde. I assume that then you have to distill the acetaldehyde out of
the water.
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Marvin
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I dont think you should be adding oxygen before, maybe you are confusing catalyctic dehydrogenation with catalyctic oxidation. Youd distil
acetaldehyde hydrate out of the water, which has a much higher boiling point.
Dehydrogenation, loss of H2, depends critically on the temperature of the catalyst for good yeilds, if you get a lot of undecomposed ethanol its
probably far too cool.
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solo
International Hazard
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Note : here is a recent posting on the subject at the Hive,.......".Novel Discussions"
slothrop
(Newbee)
12-17-02 10:58
No 390260
Benzyl alcohols to Benzaldehydes
From Synlett 2002, 12, pp2041-42,
A Novel and Efficient Oxidation of Benzyl Alcohols to Benzaldehydes with DMSO Catalyzed by Acids
Typical procedure: A mixture of 557 mg of benzyl alcohol, 0.15 mL of HBr (48 %) and 5 mL of DMSO was stirred in an oil bath at 100°C. TLC (petroleum
ether/diethyl ether, 1:1) was used to indicate the completion of the reaction (3 h). To the reaction mixture were added 5 mL brine followed by
extraction with 30 mL of diethyl ether. The ether layer was washed with brine (5 mL x 4). Evaporation of the ether and subsequent buld to buld
distillation produced 530 mg of benzaldehyde in 95 % yield.
//Tyrone Slothrop
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Organikum
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ACETALdehyde
hey, SOLO it´s acetaldehyde not benzaldehyde and I can by no way discover how to adapt this procedure for acetaldehyde.
So this will be grounded in my stupidity please tell me what I overlook.
Madscientist, am I right if I guess that Cu oxide is the catalyst in the furnace-tube reaction? Or what?
Pleaze all tell the whole story not missing the unimportant important details like whats the catalyst is. Yes?
thanks
ORG
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madscientist
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That procedure for preparing benzaldehyde from benzyl alcohol is actually of use. If an equamolar quantity of ethanol was substituted for benzyl
alcohol, I suppose that procedure could be used to prepare acetaldehyde.
It's copper metal, not copper oxide, to my knowledge.
I weep at the sight of flaming acetic anhydride.
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Organikum
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Don´t think so but I am not sure
I don´t believe that it works for EtOH -> acetaldehyde, not at least because the author doesn´t claim thus (and what chemist wouldn´t if there was
a chance it could?).
I remember also having read that not but....
I will try to look it up and find out whats up, also I won´t waste HBr on something what is doable with a plain coppertube.
Anyway, I have found this nice PowerPoint presentation: "Oxidative Preparation of Aldehydes and Ketones" It´s a good one IMHO:
[Edited on 19-12-2002 by Organikum]
Attachment: acetaldehyde.ppt (348kB)
This file has been downloaded 6619 times
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solo
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RE: aldehydes
Organikum: I just assume it would work, no proof just a feeling after seeing how it works on benzaldehydes. I liked the prsentation al aldehydes and
ketones, I learned something.
I will be asking you about some details about the biotransformation .......as I set up my unit
Greetings, from Latin America
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blazter
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tube furnace
I have experimented a bit with a tube furnace to hopefully use it to produce acetaldhyde and formaldhyde. While i did not actually get it to work i
did find that when i just had a stream of ethanol vapors from my boiler into open air i could put a pre-heated coil of #14 copper wire into the stream
and it had a "shimmering" appearence. Also, while the heated coil was in the stream the vapors were no longer visible in the air as they were before.
I assume that the reason the vapors were no longer visible was that they were converted so a vapor with a MUCH lower boiling point and therefore
volitalized fully in the air. The tube furnace i have never worked because there was no way for me to admit a stream of air into the system to mix
with the ethanol vapors. Sometimes i fould that when just starting the contraption, and pre-heating the catalyist tube there was some white vapors
visible coming out of the condenser, but these quickly dissappeared. My guess is that the air already in the system was consumed and only a tiny
amount of ethanol was reacted. Hopefully, as i get more time I'll add a fan or fish tank bubbler to get a steady stream of air.
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DeusExMachina
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I didnt have time to read all the posts but I would like to see if this would work for making the acetaldehyde. Someone said that
C2H6O and H202 plus a catalyst will make acetaldehyde.
C2H6O + H202 + HNO3
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DeusExMachina
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sorry, that post got messed up and I dont know why I can't edit it. I was asking if C2H6O + H202 + HNO3 = C2H4O
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solo
International Hazard
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Here is a recent post on acetoaldehyde synthesis recently posted on the Hive, at
http://www.the-hive.ws/forum/wwwthreads.pl
Captain_Mission
(Stranger / Eraser)
12-20-02 17:50
No 391191
acetaldehyde can be made from acetylene using HgSO4. It´s just a normal alkyne hydration forming an enol CH2=CH-OH, wich isomerises to CH3CHO.
I hope this is a good source.........
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Organikum
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no air needed!
Hey blazter, you don´t have to blow air into the tube and it must not be as hot as most believe. If your copper glows you are far to high with
temperature.
I found this nice setup on the net:
The start of the reaction can be seen as the copper in the tube gets brighter.
The hydrogen is catched over water on the left side. Before firing up the burner the EtOH is boiled until you see it condensing in the tube.
And thats it. Thanks to Dr.Blume Germany for this 
ORG
[Edited on 13-4-2003 by Organikum]
[Edited on 13-3-2004 by Organikum]
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solo
International Hazard
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RE: synthesis of acetaldehyde
Acetaldehyde may be conveniently prepared by distilling from paraldehyde in the presence of a trace of sulfuric acid; an efficient fractionating
column should be used..........solo
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trinitrotoluene
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Today I mixed 10ml of freshly distilled 95% ethanol with 15ml of 30% H2O2 in a 250ml flash. I then shook the mixture, after that I noticed a smell,
the smell it a fruit like oder which as described in the book may be some acetaldehyde. I'm not sure how much though.
TNT
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Polverone
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ethylene glycol - again
Well, I've again found reference to the preparation of acetaldehyde from ethylene glycol. The first was from The Chemistry of Carbon
Compounds (forget full title, multi-volume set). It says that acetaldehyde can indeed be prepared by heating ethylene glycol with dilute H2SO4.
Unfortunately, no details were given. The original reference seems to be from a Russian chemistry journal from 1902 - not the most accessible
reference. Under the same heading it said that passing ethylene glycol vapors over alumina at 200 C gave a mixture of acetaldehyde and polymerization
products.
I found more confirmation in Wheland's Advanced Organic Chemistry (1949), though again details of the experimental conditions are not
given. Finally, a recent Tetrahedron Letters article mentioned the conversion of ethylene glycol to acetaldehyde by H2SO4, though the authors were
investigating the mechanism with computer simulations so there were again no lab details given.
If I still had ready access to my lab equipment you can guess what I'd be trying this weekend.
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Organikum
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most simple and OTC from pyruvic acid
When you boil pyruvic acid with diluted H2SO4 you get acetaldehyde boiling out of the reaction.
Pyruvic acid is easily prepared from sodium pyruvate available over the net (unsuspicious not so expensive) or at the healthstore (expensive).
Stochiometric amounts of HCl should do the trick I guess.
Thats from a 1992 Chembook (for teachers education / university).
This is not the cheapest way but:
Pyruvic acid is also conveniant prepared by biosynthesis - I look this up and post the patent numbers next time plus personal experiences so there is
any interest shown.
I prepared DIOXANE several times now from ethylene glycol in very good yields - this solvent is very useful! How to twist this to get acetaldehyde -
no clue. For sure simple boiling with H2SO4 gives DIOXANE - and thats fine. 
thats a good one isnt it?
ORG 
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KABOOOM(pyrojustforfun)
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awesome!
pyruvic acid is the end product of glycolysis. fermentation then use it to make ethanol via ACETALDEHYDE . if we could deactive the last involved
enzyme (not sure for name but maybe aldehyde hydrogenaze) ...
alcohol dehydrogenase is a natural enzyme that does the reverse reaction (alcohol to aldehyde)
the condensed chemical dictionary states that pyruvic acid is derivated by <i>dehydration of tartaric acid by distilling with potassium acid
sulfate</i> so both decarboxilation and pinacol rearrangement happen in this reaction. just needs wine lees (so fucked, all alcoholic drinks are
forbidden here!  )
anyway what about doing the pyruvic acid decarboxilation by distilling its salt with excess alkali in a aqueous sol?
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chloric1
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AYY Carumba!
KABOOM! Man that sucks no alcohol. I must admit in many ways alcoholism is like a plague here in America but there many more who know how to
rationaly use this substance in moderation. HOw better a way to manage high cholestriol than a glass of Pinot just before bedtime Also, when petrol fuel shortages reach a crisis level we only have our vast
midwestern cornfields to turn to to power out generators and automobiles.
As far as acetylaldehyde goes, it looks simple and straight forward and I am anxious to make about 100 ml or so for various uses. I don't know
about the availability of the various yeast in Iran but starch can be converted to dextrose by boiling in water acidified with a small amount of HCL.
Dextrose is easily fermented to ethanol solution in a few weeks time.
Fellow molecular manipulator
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KABOOOM(pyrojustforfun)
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no problem with alcohol man (I have <i>lab</i> recipe for fermentation and further purification. spirited EtOH is also available ), I was
talkin about wine lees as a source of tartaric acid it's probably purchasable where wines are made traditionally. maybe even supermarkets have
it. should check ...
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Magpie
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another (tough) route to acetaldehyde
From my 2qtr notes in organic chemistry: Aldehydes can be made from the corresponding alcohol using CrO3*2pyridine complex (Collins reagent). Solvent
is CH2Cl2; temp 25 deg C. This has the advantage of not carrying the oxidation too far, which would yield an organic acid. (This is a problem with
the Na2CrO7/H2SO4 synthesis, as aldehydes are easily oxidized.) The pyridine serves to "poison" the reaction. Be warned that pyridine is
nasty stuff (really sickening odor) and is a carcinogen, I believe. I would recommend having very good ventilation if this is used.
I realize that with all these nasty reagents it would be easier to just buy the acetaldehyde!
Organikum: I like your photo from Dr. Blume. I would have killed for those jacks in organic lab last winter. I also noted the clay tile bench top.
In the USA we normally use a 1" thick epoxy resin.
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Organikum
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Torula yeast produces up to 25g per liter of pyruvic acid during his fermentation cycle.
Make the sodium salt in situ as pyruvic acid is hard to isolate - evap, filter wash - HCl, voila - pyruvic acid.
MagPie:
If you use an simple matter-converter acetaldyde is no problem at all. For most here a matter converter is more easily in reach as this famous reagent
ya know?
Yes! Dr. Blume rulez!
[Edited on 21-11-2003 by Organikum]
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Theoretic
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From various chemistry books i've seen evidence that copper doesn't act as a simple catalyst. One says that the hydrogen made is absorbed
into the copper and then is oxidized by air. The other, among other oxidizing agents that produce acetaldehyde from ethanol, lists CuO at 300 C, so I
assume it's much more efficient than simple copper. I guess that the initial "white fumes" were the result of the reaction that
happened untill the copper became saturated with hydrogen and all the outer CuO layer was consumed. I assume if the tube was heated strongly enough,
the hydrogen would desorb and there would be no problems. Looking at the evidence, I suggest finely powdered CuO in a copper tube (taking no
chances).
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