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Author: Subject: Acetaldehyde synthesis
plante1999
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[*] posted on 6-7-2013 at 16:46


If I get a good source of ethylene, I might try the Wacker process in an all glass apparatus. If one got Palladium chloride, and ethylene, as well as the ground glass, it is a fairly simple experiment I think. It happens that I have a 5g Aldrich palladium chloride, of which only 0.7g is for my personal use. I remember reading that 0.5% PdCl2 was used, that means I could do a 100ml reaction solution.

I just need ome ethylene and more ground glass, and I would be ready to go.




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[*] posted on 7-7-2013 at 16:37


Here is some pictures if people are interested:

<img src="http://i1103.photobucket.com/albums/g469/plante1999/DSC00187_zps1749ce00.jpg" width="800" />




I'm actually doing a test with non-regenarated dilute palladium chloride solution and propylene, due to my easy access to it, see the mapp pro thread.

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: reduced image width]

[Edited on 7/8/13 by bfesser]

[Edited on 8-7-2013 by plante1999]




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[*] posted on 7-7-2013 at 18:02


For some reason, I have hard time making hydrochloric acid solution of palladium chloride to react with double bonded organic compound, like styrene, propylene, alpha pinene etc... Even when boiling hot. Does anyone got an idea of the reason that makes the experiment not very success full? Apparently the reduction of palladium chloride by double bonded compound was "very easy" and discovered in 1895.



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[*] posted on 7-7-2013 at 18:09


It's interesting that you're the first person here ever who really wants this. I guess something happened in "I quit", TLDR. A good source of ethylene can be home cooked. 0.5%...references?

...btw...Olefin Oxidations and Related Reactions from Organometallic Reactions v3 1972:

One liter of an aqueous solution containing 17.8 g PdCl2 is charged into a flask connected with a gas burette filled with ethylene and heated up to 50°. After shaking for a few minutes 2.6 liters of ethylene are absorbed and palladium metal is precipitated. Acetaldehyde is isolated by distillation (yield 96%).

...

An aqueous solution containing 1.78 g PdCl2, 150 g CuCl2.2H2O, and 24 g Cu(OAc)2-H2O per liter is charged in a vertical, heatable glass pipe filled with Raschig rings. At 90-95° a gas mixture of 84% per volume C2H4 and 16% per volume oxygen is passed through the solution with a rate of about 50 liters/hr-liter catalyst. Acetaldehyde is separated from the un- reacted gas by cooling and/or scrubbing with water. The space-time yield under these conditions is 10-15 = g/(l X h) The initial muddy (by basic copper salts) solution becomes dear during the reaction, and a constant oxidation degree is reached. This procedure represents the model for the commercial "one-stage process."

The procedure of the "two-stage process" can be carried out with the same solution if ethylene and air (or oxygen) are introduced alternatively. Ethylene is replaced by air when cuprous chloride begins to precipitate and it is fed again when the solution becomes slurried by copper oxychloride. If the reaction is carried out for a longer time the water removed by the unreacted gas must be compensated for by continuous feeding. After several days of reaction an insoluble precipitate of copper oxalate accumulates. It is formed via chlorinated by-products. In this reaction low amounts of mono-, di- and trichloroacetaldehyde, ethylene chlorohydrin, and others can be observed. Similar side reactions take place with higher olefins.


I wonder if the precipitated Pd is effective for something, since otherwise it just gives 3 grams of acetaldehyde.




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plante1999
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[*] posted on 7-7-2013 at 18:38


Thanks, it was a recent crappy chemistry book, I looked in my books, and found a much better reference in Catalysis and chemical processes, page 266, it tells 4g/L as the concentration of palladium chloride.

Much thanks for the reference, I will make the two needed salts for this to try it via the two stage process.

I guess precipitated Pd can be used to hydrogenate thing, or turn to nitrate with HNO3.




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[*] posted on 13-7-2013 at 13:10


It works!!!!!


Muhahahaha.


I made a solution of 0.2g of palladium chloride, approx 15g of copper chloride and 1.4g of copper acetate in just enough water to make to make 100 ml solution. It took some time, but everything dissolved.

After this, I made an apparatus with a shortpath, room tempt water filled condenser. The reaction flask had two neck, one with the shorthpath, and one with the gas dispersion tube. A solution of 50ml sulphuric acid and 20ml 70% ethanol was made, and the reaction flask was braugth to boilling. After that, the sulphuric-ethane generator was heated until ethane steadily got out of the flask, after some point a white precipitate formed very rapidly in the flask (copper I chloride), the flask solution turned yellow and a distillate condensed, altough the condenser was not enough efficient. Then, air was passed in, and the solution, slowly all the copper chloride dissolved back to make the green solution back.


Ii is EXTREMLY nice to see the process in action, I must make some change to it, so I can make acetaldehyde out of ethanol!

I will keep everybody updated!

[Edited on 13-7-2013 by plante1999]




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[*] posted on 13-7-2013 at 14:55


Ok, so I did another test, with ice cooled water, and it still didn't condensed much acetaldehyde, It did however made lots of HCl gas, I really need more copper acetate buffer in the reaction mixture, I'm pretty sure I also need to add new HCl now. I pretty much made the same smell as when you oppen a bottle of 30% HCl in the summer.

I will need to pass the gas in water I guess.

When the procedure will be successful, I will work on making formaldehyde from Silver and methanol, and make pentaerythriol, for the pyro out there. However, I will probably try to polymerise each to paraformaldehyde and metaldehyde respectively. If anyone want to help me in this project, there is a link in my signature.

here some pictures:

The makeshift apparatus, the white on the reaction flask is due to burning residue:

<img src="http://i1103.photobucket.com/albums/g469/plante1999/DSC00193_zps7d85ec01.jpg" width="800" />


The catalyst solution being used up:




The catalyst solution being regenerated:



The regenerated solution:



<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: reduced image size(s)]

[Edited on 7/14/13 by bfesser]




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shocked.gif posted on 20-7-2013 at 19:36
Using acetone


You can use acetone with a copper oxide catilist. It does make fumes so be careful. Heat copper till red hot then suspend it over some acetone.
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[*] posted on 21-7-2013 at 01:50


This is just an idea for you guys to evaluate: You all know Elmers's glue is made out of polyvinil acetate polymer and may be some water. The idea would be to dissolve some NaOH in the mixture to hidrolize the ester, maybe add some depolymerization promoter compound and then introduce the mixture into a distillation apparatus, distill the lower fractions, mainly water, and then dry distill the slug to obtain mainly vinyl alcohol and higher fragments of the chain. Of course the vynil alcohol should turn ipso facto in to low boiling acetaldehyde and the lower chain polyvinil alcohol could be added to the next dry distillation. As a bonus one would obtain sodium acetate. How do you guys see this idea? I'm basing it on the thermal depolymerization of styrene and delrin polymers and AFAIK polyvinil alcohol should depolimerize too. Sorry for my english and have a nice day!
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[*] posted on 21-7-2013 at 08:59


Has anyone attempted this synthesis? It seems like a very straightforward and simple way to produce Acetaldehyde. I browsed through the entire thread and didn't see anyone else post this although I may have missed it.

If nobody else has attempted it so far, I can reproduce the experiment, however I only have access to potassium dichromate rather than the sodium salt.

Attachment: Synthesis of Ethanal.pdf (37kB)
This file has been downloaded 694 times

[Edited on 21-7-2013 by BobD1001]
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[*] posted on 21-7-2013 at 09:19


An estimated 1.238.876 people have reproduced this synthesis since its invention, for by accident its the standard laboratory procedure for making acetaldehyde and for a long time was a favorite in teaching chemistry.

It is for most here impractical for chrome-salts are hard to come by in most places of the world, up to impossible to legally aquire them as a private person not to talk of bigger amounts.

Thats why other pathways are needed.
For those with the chromium problem at least.

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[*] posted on 21-7-2013 at 10:15


sry if this already covered. b-alanine in (aq) -0HCL. Bleach or HTH.



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[*] posted on 22-7-2013 at 02:53


Hi, I just happened to try on a very small scale the reaction of 95% ethanol and TCCA, so into few drops of ethanol I put some 200mg of TCCA. I expected a spectacular reaction as TCCA loves to do with things (burst into flames), however i didn't notice even heating but a strong smell appeared I'm not sure what it is, somewhat bitter and a little lacrimatory if you sniff too close(not like chloramine !), I suspect this can be acetaldehyde. As I read there was mentioned about it's synthesis from Ca hypochlorite and ethanol, BUT that was very uncontrollable unlike what I observed with TCCA (though it was small volume and I'm not completely sure on aldehyde).
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[*] posted on 22-7-2013 at 03:16


Do you have a dichromate salt or CrO3? If so, then dissolve some of this in dilute H2SO4 and then add a small quantity of ethanol. Compare that smell with the smell you obtain from TCCA and ethanol.

I am willing to perform your experiment as well and smell the result. I know the smell of acetaldehyde and can certainly tell whether it is that compound or some other stuff. I do not really like the smell of acetaldehyde, but it is not so bad as some people want you to believe.




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[*] posted on 22-7-2013 at 03:24


Hmm, I have some ammonium bichromate if it'll work I can try (isn't that a cognac-like smell at low concs.? ), however I'm afraid that chlorine smell from TCCA admixed with what supposedly is acetaldehyde can make it indistinguishable.. A better test is needed (I have no distillation apparatus also), and be careful if you scale up or do it in glass (who knows), also I want to note my TCCA has significant amounts of boric acid in it, just in case. Thanks!

[Edited on 22-7-2013 by papaya]
EDIT: What is written in wiki https://en.wikipedia.org/wiki/Potassium_bichromate

"Ethanol determination

The concentration of ethanol in a sample can be determined by back titration with acidified potassium dichromate. Reacting the sample with an excess of potassium dichromate, all ethanol is oxidized to acetic acid:

CH3CH2OH + 2[O] → CH3COOH + H2O
... "
There must be an error or everything depends on concentrations?

[Edited on 22-7-2013 by papaya]
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[*] posted on 6-9-2013 at 04:53


I remembered a chemistry demonstration where a copper penny is heated until it glows, then suspended in acetone vapors. The hot metal catalyzes the oxidation of acetone, which heats the penny, sustaining the reaction.

The oxidation product appears to depend upon how much oxygen is mixed with the acetone vapor. Oxygenated vapor forms acetaldehyde; anoxic vapor forms ketene.

I wonder if it would work to take a metal pipe and put a copper scrub pad inside, connected to a power supply to give it the initial heating. An aquarium pump passes air through acetone, forming an oxygenated vapor. This passes over the hot copper, then into a condenser.


www.job-stiftung.de/pdf/versuche/Catalytic_Oxidation_Acetone...
http://www.rsc.org/Education/EiC/issues/2012September/cataly...
http://lecturedemos.chem.umass.edu/chemReactions5_4.html





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[*] posted on 6-9-2013 at 05:42


I tried this demo a few weeks ago with a bit of copper wire.

<img src="../scipics/_warn.png" /> <em>Beware; one of the products, ethenenone (ketene), is a <a href="http://en.wikipedia.org/wiki/Ethenone#Hazards" target="_blank">highly toxic gas</a> <img src="../scipics/_wiki.png" />!</em> <img src="../scipics/_warn.png" />

The video that inspired me to try it:
<iframe sandbox width="560" height="315" src="//www.youtube-nocookie.com/embed/bczUv043XtY?rel=0" frameborder="0" allowfullscreen></iframe>




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[*] posted on 7-9-2013 at 16:49


You could covert acetone to it by a copper oxide catilyst
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[*] posted on 10-9-2013 at 03:24


Probable viable synthesis via glucose:
1°)fermentation of glucose into lactic acid by lactobacilus
HOCH2-CHOH-CHOH-CHOH-CHOH-CH=O --> 2 CH3-CHOH-CO2H

2°)oxydation of lactic acid by conventional oxydisers into pyruvic acid
CH3-CHOH-CO2H -ox-> CH3-CO-CO2H + H2O

3°)thermic decarboxylation at moderate temperature of pyruvic acid into acetaldehyde
CH3-CO-CO2H --> CH3-CH=O + CO2(g)

[Edited on 10-9-2013 by PHILOU Zrealone]




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[*] posted on 11-10-2013 at 04:22


Is there a procedure for formation of lactic acid from glucose? Could saccharose be used too?

Lactobacillus can be obtained from yoghurt i guess.
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[*] posted on 11-10-2013 at 19:13


Lactic acid can be oxidized directly to acetaldehyde without prior conversion to pyruvic acid, by adding dilute hydrogen peroxide to ammonium lactate solution. At one time this was used as a method for assaying lactic acid in blood (a hundred years ago). Too lazy to dig up the reference but I think Dakin actually published something on this topic.

So far as obtaining lactic acid is concerned, the fermentation is not difficult. I posted something here about it and managed to obtain 1400g of calcium lactate despite being pretty damned sloppy with my process.


[Edited on 12-10-2013 by bbartlog]




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[*] posted on 11-10-2013 at 19:32


Lactobacillus can be bought from White Labs (and maybe Wyeast). It is used for making Belgian-style sour beers (lambic, gueuze among others). Lactic acid can anyways be had cheap from eBay vendors. It is also used in homebrewing for adjusting mash pH.



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[*] posted on 11-10-2013 at 20:12
Formation of Lactate from Sugars


Quote: Originally posted by Random  
Is there a procedure for formation of lactic acid from glucose? Could saccharose be used too?

Lactobacillus can be obtained from yoghurt i guess.


Process for producing a lactic acid-amine complex
Publication number EP2630114 A1
Publication date Aug 28, 2013

http://www.google.com/patents/EP2630114A1?cl=en

It looks like lactate can be produced directly from the reaction of glucose with barium or calcium hydroxide in a hot water solution.

This is also alluded to in page 335 of:

Victor von Richter's Organic chemistry: or, Chemistry of the carbon compounds, Volume 1, P. Blakiston, 1899.

"Other methods consist in heating grape sugar and cane sugar with water and 2-3 parts barium hydrate to 160C..."


[Edited on 12-10-2013 by WGTR]
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[*] posted on 13-10-2013 at 22:41
Oxidation of lactate to acetaldehyde with H2O2


Quote: Originally posted by bbartlog  
Lactic acid can be oxidized directly to acetaldehyde without prior conversion to pyruvic acid, by adding dilute hydrogen peroxide to ammonium lactate solution. At one time this was used as a method for assaying lactic acid in blood (a hundred years ago). Too lazy to dig up the reference but I think Dakin actually published something on this topic.
[Edited on 12-10-2013 by bbartlog]


Attached is a useful reference for what you are referring to. Apparently sodium lactate can be oxidized by H2O2 to acetaldehyde when the reaction is done in nitrogen, in the absence of oxygen. If atmospheric oxygen is present, then the acetaldehyde forms peroxides.

Attachment: The Oxidation of Sodium Lactate by Hydrogen Peroxide.pdf (643kB)
This file has been downloaded 604 times
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[*] posted on 14-10-2013 at 22:00


I decided to try a quick experiment, just to get a feel for what would happen with the lactate approach.

I added enough water to 10.0 g of NaOH to form a 50mL solution, under heavy stirring. In another beaker, 10.0g of dextrose was dissolved in water to form 40mL of solution. Both beakers were heated on a hot plate to 70-80C.

With the NaOH solution under heavy stirring, the dextrose solution was pipetted into the NaOH solution over a period of 30 minutes. As the dextrose was added, the color of the solution progressively went from yellow, to orange, to a dark burnt orange/black as more dextrose was added.

The pH was measured at about 14, and 50% H2SO4 was then added gradually to bring the pH down to about 6. Once the solution was neutral, the color changed from orange/black, to light clear orange. The odor of this solution was not very pleasant at all, and became more noticeable when the solution pH was adjusted to neutral. Looking through some references I realized that I had just performed "Moore's Test", even down to the point of noting the strange odor. (Page 190, Practical Organic and Bio-chemistry By Robert Henry Aders Plimmer; Longmans, Green & Company, 1915)

10mL of this solution was diluted into another beaker to form a 50mL solution, and this was stirred at 30C. 2 mL of 30% H2O2 was added, and the solution was covered and left to stir for several minutes.

I wanted to see if there would be any tell-tale odor of acetaldehyde. If it was there, it was masked by the odd caramel odor already in the solution.

After looking through the reference on the "oxidation of sodium lactate" I listed above, I noticed that they were diluting the lactate to M/50, which I understand to be 1/50 Molar. This is actually very dilute, something that bbartlog alluded to earlier. I think that trying to isolate acetaldehyde from such a diluted solution would cause many frustrations if attempted.

This quick experiment encourages me to go back to working on catalytic dehydrogenation of ethanol instead. I've managed to isolate a small amount of acetaldehyde that way, but I need to work on improving the reactor design to make it more "user friendly".

Taking some ideas from Sabatier's book "Catalysis in Organic Chemistry" and others, I've settled on a single bead-string reactor design. Round copper/magnesium hydroxide beads are threaded onto a copper wire, and the catalyst assembly is inserted into a borosilicate tube. The tube is inserted into an aluminum block (with internal surfaces blackened by FeCl3) to provide even heating, and the block is placed directly on a hot plate set to 300-350C. The hot plate surface and the aluminum block are then covered by firebricks.

The current design leaves the reactor tube in a horizontal configuration, which I don't think is best when trying to reflux the unreacted ethanol. Right now I'm recycling the unreacted ethanol manually after each batch run. The next configuration will be a vertical reaction tube, with a heater built into the aluminum block. This whole assembly will be enclosed in a couple of firebricks, to help retain the heat.


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