Author Topic: Does OTC acetaldehyde exist?  (Read 192 times)

Enkidu

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Does OTC acetaldehyde exist?
« on: June 21, 2009, 07:19:43 PM »
The only thing that I can find that is remotely close is metaldehyde, but that isn't really sold in the US.

Sedit

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Re: Does OTC acetaldehyde exist?
« Reply #1 on: June 21, 2009, 07:29:36 PM »
I looked thru a couple product databases and came up with nothing. Metaldehyde came up with a few things but the highest percentage is 3.25% so not really worth it.

Better to use a tube furnace with Cu sponge catalyst or use MAA oxidiser. The Mn(SO4)2 seems very effective for alcohols and MAA should work also.

I think thats about as over the counter as your gonna get with this one Enkidu sorry can be more help.
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Enkidu

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Re: Does OTC acetaldehyde exist?
« Reply #2 on: June 21, 2009, 08:52:59 PM »
I have been thinking about the hydration of acetylene. If I can't get the monomer or a polymer, it would be useful if I could generate the ethanal in situ for a condensation.

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Re: Does OTC acetaldehyde exist?
« Reply #3 on: June 21, 2009, 10:59:31 PM »
The fact that the neograviton method of producing BnO from toluene using MnSO4 seems like it should work pretty well for EtOH. Im not completely up to speed with the mechanics of it though so I may be mistaken. I would think that the temperature may need to be lowered but if you can synthesis Acetaldahyde this could be condensed into dilute sulfuric to polymerize it to metaldahyde and allow to to refeed the Ethanol back and give you better handling on the acetaldahyde.

I know for a fact that acetaldahyde was produced using Mangenese persulfate so if thats an option working it up like I just discribed by feeding it into an acid would be the most efficiant route that I know of at the moment.

Using acetylene needs something akin to a tube furnace just lower temepratures also doesn't it?
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Re: Does OTC acetaldehyde exist?
« Reply #4 on: June 22, 2009, 01:48:24 AM »
You may just be in luck Enkidu, ;D I just found an OTC source for it while looking for caulk in my gardge,

DAP latex caulk second listed ingrediant is acetaldahyde the first being ethylene glycol. Due to acetaldahydes volitility seperation from a solid mix like this should not be any problem when using an icewater condenser. Check into the MSDS of DAP latex caulks and you may be able to find what you need.


BTW just cause they list it as acetaldahyde don't mean that its not in its polymerised form so some cleavage maybe in order.
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Vesp

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Re: Does OTC acetaldehyde exist?
« Reply #5 on: June 22, 2009, 03:03:46 AM »
I am very interested in hearing how the DAP latex goes if anyone tries it. An OTC source of acetaldehyde would be excellent.
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Enkidu

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Re: Does OTC acetaldehyde exist?
« Reply #6 on: June 22, 2009, 04:39:11 AM »
I didn't see that anywhere... link?

http://www.dap.com/docs/msds/00010103001_english.pdf

Vesp

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Re: Does OTC acetaldehyde exist?
« Reply #7 on: June 22, 2009, 05:39:27 AM »
It mentions acetaldehyde in the PDF you've posted a few times, look for Ctrl F acetaldehyde, and you'll see that it is in very low quantities. Right?
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Re: Does OTC acetaldehyde exist?
« Reply #8 on: June 22, 2009, 05:56:23 AM »
Dont have a link but I can take a picture tommorow of it if it can focas on the lable.


[edit] I lied

http://www.dap.com/docs/msds/00010103001_english.pdf

A quick google pulled it up and it appears the ammounts (even though this aint the exact one I dont believe) are very minute. Oh well your back to making it again.
« Last Edit: June 22, 2009, 05:59:03 AM by sedit »
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Re: Does OTC acetaldehyde exist?
« Reply #9 on: June 29, 2009, 09:41:26 AM »
From the book I posted a link 2 alrady.
Some ideas:


"Acetaldehyde

This oxidation-product of alcohol is employed industrially in the preparation of certain aniline dyestuffs, and also in making paraldehyde, which has some application in medicine. The two chief sources of commercial aldehyde are the by-products of wood distillation, and the by-products of alcohol rectification. As the boiling point of aldehyde is only 21°, the compound is found in the first runnings of the distillates. From these it is separated by fractional distillation and rectification. The aldehyde for technical purposes obtained from wood is usually of about 95 to 96 per cent. purity.

Another method of obtaining acetaldehyde utilised in recent years is the catalytic oxidation of ethyl alcohol. A current of air is bubbled through warm alcohol, and the issuing vapours are led over a heated finely-divided metal serving as catalyst, in essentially the same manner as is described in the case of methyl alcohol. A process not involving alcohol may be briefly mentioned, namely, the decomposition of lactic acid into aldehyde and formic acid brought about by heating it with dilute sulphuric acid. The lactic acid solution employed is obtained by fermenting a " mash ' of potatoes with the lactic acid bacillus.

It is quite possible that these various methods of obtaining aldehyde for industrial purposes will sooner or later be superseded by processes based upon the oxidation of acetylene. In one such process this gas is led into a hot dilute sulphuric acid solution, containing not more than about six per cent. of the acid, together with mercuric oxide. The acetylene is oxidised to acetaldehyde, which forthwith distils from the hot liquid, so that the process is a continuous one. The mercuric salt is gradually reduced to metallic mercury, which can be re-converted into the oxide electro-lytically, and used again. A good yield of pure aldehyde is said to be obtained.2

1 Zeitsch. angew. Chem., 1911, 51, 2429. 2 F.P , 455370.

On a small scale aldehyde is prepared chemically as follows. Two hundred and ten grams of potassium bichromate, broken into pieces about the size of a pea, are placed in a large round-bottomed flask of about 3 litres capacity, together with 840 grams of water. The flask is fitted with a tap-funnel, and is connected with a condenser and receiver, the latter being well cooled with ice. Keeping the flask cooled, a mixture of 210 grams of alcohol (90 per cent.) and 280 grams of strong sulphuric acid, also well cooled, is slowly added through the funnel, and the mixture well shaken. Much heat is evolved, and aldehyde distils over, with more or less water, acetal, and alcohol. Towards the end of the operation the heat of a water-bath may be applied to the flask. The distillate is rectified on the water-bath at about 50°, the vapours being led through a reflux condenser, which retains water and alcohol, into receivers containing anhydrous ether. The ethereal solution of aldehyde is now saturated with gaseous ammonia (dried by passing over lime), when the aldehyde-ammonia separates out as a white, crystalline mass. This is separated, drained, washed with ether, and dried. Pure aldehyde may be obtained from it by dissolving it in an equal weight of water, and distilling the solution on a water-bath with dilute sulphuric acid (1.5 parts of cone, sulphuric acid to 2 parts of water). The distillate is collected in a cooled receiver, and dehydrated with calcium chloride.

Acetaldehyde is a colourless, mobile liquid, sp. gr. 07951 at 10°, and boiling point 21°. It serves for the preparation of paraldehyde as already mentioned. By the action of aluminium alcoholate it is converted into ethyl acetate.1 Thus ethyl acetate can be produced from acetylene."



Also Alanine + bleach = acetaldehyde + acetonitrile depending on the conditions and ratios.
« Last Edit: June 29, 2009, 09:47:14 AM by Goldmember »

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Re: Does OTC acetaldehyde exist?
« Reply #10 on: July 06, 2009, 10:47:47 PM »
Quote
A process not involving alcohol may be briefly mentioned, namely, the decomposition of lactic acid into aldehyde and formic acid brought about by heating it with dilute sulphuric acid.

Ethyl lactate avalible as a green paint stripper at Lowes or Home Depot and the only listed ingrediant hydrolyzes in H+/H2O or OH-/H2O to Lactic acid and Ethanol.

This sounds as a viable source of both Formic acid and the Acetaldahyde given that the yeilds are good as hydrolysis of the Ethyl lactate with H2SO4 should take it all the way to Acetaldahyde and Formic acid. The condenser could be kept at a temperature which promotes reflux of the ethanol but allowing the Acetaldahyde to pass should in theory yeild a large amount of Acetaldahyde and Formic acid/EtOH solution which could be used as is dissolved in EtOH or better precipitated as the a formate and used that way.

Can we have more information on this because to much H2SO4 degrades Formic acid to Carbon monoxide to not room for ignorance here.

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Vesp

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Re: Does OTC acetaldehyde exist?
« Reply #11 on: July 07, 2009, 07:20:52 AM »
Depending on the conditions, you may also get ethyl formate as a product. So I guess that is something to consider.
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Re: Does OTC acetaldehyde exist?
« Reply #12 on: July 07, 2009, 12:22:19 PM »

"Can we have more information on this because to much H2SO4 degrades Formic acid to Carbon monoxide to not room for ignorance here."

Yes carbon monoxide is a by-product if conc`H2SO4 is used alone. Addition of manganese dioxide avoids this I think.

There are many alternatives out there if one chose to start from lactic acid.

This is interesting.The use of manganese sulfate in conjunction with permangante to effect a selective oxidation.Could be made to work on piperic acid etc.I know this is analysis scale,but the underlying principle remains the same:

http://docs.google.com/gview?a=v&q=cache:iPi8iqmw2lgJ:www.corn.org/methods/J-36.pdf