Acetaldehyde synthesis

Quote: Originally posted by bbartlog

His original publication is in J. Biol. Chem., 1906, 1, 171. For some reason I can't find this online any more, although a followup paper that he published in the same journal in 1908 is available via Google Books.

I tried something else with less expensive metals/compounds as silver and aluminium oxide:

reduction : CH3CH2OH --(H2SO4(>150*C)/-H2O)--> H2C=CH2 (ethylene)

oxidation : H2C=CH2 + Air --(Ag powder deposited on active charbon/azbest at 200-300*C)--> (CH2-CH2)O (ethylene oxide)

transposition : (CH2-CH2)O --(Al2O3 powder deposited as silver, at 200-300*C)--> CH3-CH=O (ethanoic aldehyde)

and seems to work...
also I can obtain ethilene oxide, through this process, wich is a extremly useful reagent

Here is a process of making acetaldehyde:

And here is the another process:

And the Ag powder / Al2O3 powder can be easily spread in the glass wool:
Take a piece of glass wool and pass it over hot steam. Then put it into a closed jar with some catalyst powder and give him a really good shake.

If you have problem with the silver powder (I remember that I have actually some problems, because silver must be powdered, not granules)... try this:
Put a piece of silver into nitric acid.
After it dissolves, wash in the solution of AgNO3 some copper wool (from electric wires) until a silver film start to form on copper.
Now you have the silver powder on copper wool

also you can try to make the silver mirror reaction using the glass wool in the solution of glucose/sucrose + NaAg(NH3)2 ... but I think is too complicated for our purpose

i have also come up with a few reactions to make acetaldehyde .pls consider them ,we can then choose the most practical one

1.In the beginning pages ,i saw that some members were having trouble with oxidizing ethanol to acetaldehyde using hydrogen peroxide.
but ethanal can be made from ethanol using peroxide if FeSO₄ is added to it .the mixture of peroxide and Fe⁺² is called fenton's reagent
http://en.wikipedia.org/wiki/Fenton%27s_reagent

2.some members suggested doing dehydration of glycol using sulphuric acid but ended up getting dioxane.
instead of H₂SO₄ ,anhydrous ZnCl₂ can be used to get ethanal

3.another member suggested doing ozonolysis on propene ,but it is risky.
alternatively,one could pass propene through cold ,dilute KMnO₄ and get propan 1,2 diol which can be subjected to periodic cleavage using HIO₄ .
even lead tetra acetate can be used if periodic acid is not available

periodic cleavage -http://en.wikipedia.org/wiki/Glycol_cleavage
lead tetracetate preparation-https://www.erowid.org/archive/rhodium/chemistry/lead.tetraa...

if propene is not available ,then propylene oxide(methyl oxirane) can be converted to propan 1,2 diol using acidic or basic treatment ,then the above mentioned diol cleavage can be carried out

propylene oxide http://en.wikipedia.org/wiki/Propylene_oxide

sorry, after posting this link i realised that propylene glycol is directly available-http://en.wikipedia.org/wiki/Propylene_glycol

4.we could also treat 1,1 dichloroethane with base to get gem diols that immediately tautomerise to acetaldehyde
ethylidene choride http://en.wikipedia.org/wiki/1,1-Dichloroethane

5.the sommelet reaction[http://en.wikipedia.org/wiki/Sommelet_reaction could be tried(as Hexamine is very easy to make https://www.youtube.com/watch?v=d2N0zAoVYew ,although the reaction is specific for benzyl halides ,the wiki page says that some aliphatic aldehydes have been prepared

6.finally nitroethane can be converted to acetaldehyde using the nef reaction with 70% yield of acetaldehyde
nef reaction-http://en.wikipedia.org/wiki/Nef_reaction .the yield of acetaldehyde could be increased to 90% if Fe/HCl is used instead of sulphuric acid as told in the wiki page according to this journal-http://www.tandfonline.com/doi/abs/10.1081/SCC-200051681?jou...
if anyone is interested i will upload it tomorrow


P.S. - one member wanted to know how to get selenium dioxide for making methylglyoxal http://en.wikipedia.org/wiki/Methylglyoxal from acetone,which could then be oxidised to convert the aldehyde to acid and then heated to get acetaldehyde by decarboxylation .

IIRC,when i was small ,we used to make solar cells from selenium wafers found in old transistor radios .but i dont think we can find those radios nowadays
also .if the selenium oxide is used to oxidise ,then SeO₂ would itself get reduced and i remember reading somewhere that hydrides of selenium stink to high heavens ( even worse than hydrogen sulphide)
H₂Se -http://en.wikipedia.org/wiki/Hydrogen_selenide









[Edited on 3-11-2014 by CuReUS]

As the end of the school semester approaches, I find myself with less and less free time in the lab. For this reason, this project is not documented as well as I would like to have it. Along the thread of ethyl alcohol direct dehydrogenation, I'm posing some pictures of how I assembled a single bead string reactor. It has some issues. For one, I would probably choose to replace the glass reactor tube with a similarly sized stainless steel one. Stainless has a bit more elasticity, and is easier to bend safely. Like glass, stainless has low thermal conductivity for a metal. Also, I can more easily braze stainless fittings together than I can fuse borosilicate glass. Thermal shock is not as hazardous with stainless, either.

I tried some initial experiments dehydrogenating alcohol with this set up. The reactor and catalyst are doing their respective jobs, but a better configuration is needed in order to vaporize the alcohol (without superheating the liquid), as well as a better set up to condense and separate the product from the excess alcohol. The excess alcohol also needs to be automatically sent back to the vaporization unit. As such, this design mainly serves to give others ideas; it is not a finished project intended to be used as a cookbook design.

A wooden dowel is covered with two-sided adhesive tape, and sandpaper is wrapped around the dowel one time (80 grit is used instead of 320 grit; 320 grit is unnecessarily slow):



The finished dowel with 80 grit sandpaper is used to sand a groove into the fire-bricks (2300F type), pausing to vacuum the dust from time to time. Afterwards, Kanthal resistance wire is wound tightly around the same dowel.



The wire loosens up once tension is removed from it. The coil is grasped on either end, and carefully stretched out to the correct length. The coil will be a little loose on the dowel, and will not fit into the fire-brick. To remedy this problem, one end of the coil is taped to the dowel, and the other end is held loosely to the dowel with one hand, while spinning the dowel with the other hand. This easily tightens the coil around the dowel, and it can now be fit into the fire-brick. Once the coil is untaped from the dowel, it will expand out slightly in the fire-brick, unspinning a few times. Space out the turns a little if this is necessary. Finally, two more fire-bricks are placed on top, leaving the wire ends hanging out from in between the bricks.

Copper sulphate pentahydrate and magnesium sulphate heptahydrate (Epsom Salts) have almost the same molar mass. Prepare a supported copper catalyst by weighing out 5 parts of copper sulphate pentahydrate to 1 part of magnesium sulphate heptahydrate by weight. Dissolve this in cold water with heavy stirring, and precipitate the hydroxides with a stoichiometric amount of sodium hydroxide. Filter and wash the blueish precipitate on a Buchner funnel with vacuum. Don't allow the precipitate to dry fully. While still damp, form small beads with the precipitate. Thread the beads on thin copper buss wire like a necklace, leaving small loops in between each bead to space them out. When dry, the beads will shrink roughly 50%. The dried beads should be about 70-80% the inside diameter of the reactor. Experience (and a mold) will help determine the correct size of the wet beads.



The following set up was not very effective in actual operation, but photos will be posted to document the process.



With a couple of hundred watts input to the reactor coil, temperatures in the tube averaged about 300C. This is about the temperature needed for alcohol dehydrogenation with this catalyst, while also allowing for long catalyst life. Higher temperatures work better, but the catalyst sinters, becoming ineffective as its surface area decreases. The finished "stack", as well as the reduced (and re-oxidized by room air) catalyst is shown.



[Edited on 11-4-2014 by WGTR]

Quote: Originally posted by Cheddite Cheese

Nitroethane is even harder to get than acetaldehyde.

Quote: Originally posted by Oxirane

For most private chemists(or maybe in this context, cooks), nitroethane would be something that was more likely held behind locked doors than those the hazardous substances legislation generally requires. Using nitroethane for acetaldehyde sounds something like making benzoic acid from benzaldehyde.

Quote: Originally posted by WGTR

Methanol dehydrogenation is easier than that of ethanol. In fact, the above-mentioned catalyst is too active. Much of the formaldehyde will decompose into hydrogen and CO.

Quote: Originally posted by Oxirane

Do you mean that if my catalyst bed is too large, it will decompose most of formaldehyde?

Quote: Originally posted by Oxirane

I understand the linked paper as following: - First in solution are dissolved nitrates of Mg, Ca, Sr and Cu, then mixed in Silica gel, then stirred, filtered, dried and calcined. - Then nitrate of barium is dissolved ontop of the all previous, and stirred, filtered and finally calcined all over. -Then the catalyst is flushed with hydrogen for 2 hours at 300C to produce active catalyst. How can calcium, strontium and other be calcined at 450C from their nitrates while their decomp temperatures are way over 600C? Both temps are somewhat easy to achieve with normal gas burner with insulated container, but that would bring some low-decomposing oxides, like copper, into such high temperature, could we be afraid of heating them "dead", as some mentioned CaO can be done?

Quote: Originally posted by Oxirane

Is the strontium necessary, or should it work with Ca+Cu+Mg+Ba only? How should the catalyst be protected from air, or should it be prepared in situ for each dehydrogenation reaction? Once the cats are applied on the SiO2 substrate, it don't have to be done again anymore, but most likely all the metals will be coated by an oxide layer the second they meet the atmosphere. Should one use pure copper only for formaldehyde dehydrogenation if the reactivity is too large for previous metals? It has been demonstrated that pure copper tube heated to dull red was capable of dehydrogenating ethanol into acetaldehyde in Versuchschemie forum. They got from several hundred ml's of ethanol a 100ml of acetaldehyde. They never tested how long would the catalyst live.

Brilliant, thanks for the information. I will have to reek through the topic with time and read the documents as well.

Could the impregnation of silica gel be done in such way that copper and magnesium sulfates are dissolved in water, silica gel is added and stirred so they soak up, and then sodium hydroxide is introduced until no more precipitation occurs, and then filtering, washing and decanting the silica gel? This would save the need for preparing water soluble nitrates. Calcium chloride could also be added, since this co-precipitates as a calcium hydroxide. This would need the heat to be brougt at 580C at calcination stage in order to decompose the water form, but how important calcium oxide promotor will be, is another matter. Calcium hydroxide is also quite water soluble in relation to catalytic amounts deposited, so upon washing the silica gel with small amounts of water could dissolve most of the deposited Ca off.

I am planning to use the apparatus I presented in acetanhydride topic. The setup is somewhat general and the operating principle is simple. The reactor could be placed vertically as well, but this way the catalyst will hold in there easier.

Unreacted methanol is always more preferable than decomposition, since methanol can be recirculated indefinitely through the bed with refluxing recirculation, but CO and H2 are total loss.

I don't believe 300C will sinter metallic copper in any reasonable time. Other tale is when using gas torch which can put 800-1200C surface temps.

That only shows that "I think" is not worth of "I know". It should be taken into consideration, then. The germans got, as far as I know, acetaldehyde made from ethanol by just heating copper tube without any packing, so even some copper wool would increase the surface area by thousands of times.

I need to do some tests on that silica gel-hydroxide subject. If silica gel absorbs sodium hydroxide, or copper sulfate is absorbed inside and reaction is incomplete, there may be some side-effects. Copper sulfate can be pyrolyzed at over 600C, but that's rather high temperature. This was my first plan because of its straightforwardness.

And I obviously have to assemble the reactor too.

Hi folks, I custom made a new alcohol oxidation reactor, since I broke the old one (I almost cried).

I will also try to oxidize alkanes with it, C3-C6 to see what I can get, and how far the oxidation goes, hopefully not till H2O+CO2. Note that the kanthal filament will be inside the glass tube, instead of heating the glass wall, similar to a ketene lamp.

Hi WGTR tube furnace are the way to go, I had trouble finding someone who would forge me NS-quartz tube end joints made of ceramics or graphite, so I decided to go with glass. I have it prepared with a glass blower for 30dollars + thermometer for 8dollars.

When I made acetaldehyde with catalytic dehydrogenation. I never let O2 into the system. Just let it boil and react with copper wire, the overhead condenser was on max cooling capacity i.e. below the boiling point of acetaldehyde @ around 5-10°C. At this temp the acetaldehyde slowly makes it into a trap kept at -30°C. This way I could make some 20-30ml pure acetaldehyde at each 8hrs run. I send a sample of it once to a friend who measured it with HSGC-MS and said it is of lab grade purity.

Of course you can let air into the reaction zone to speed the process but I think you would only complicate things.

The reactor will work vertically the uncondensed liquid will flow back to the reboiler.

Catalysts in mind:
Standard copper oxide made with anodic oxidation of copper metal.
Silver oxide on ceramic rings.
Chunks of catalysts from a catalytic converter, from diesel ang gasoline car too. (diesel has too much platinum and it favors the oxidations to go way too far, but we will see)
Copper oxide on graphit, pressed into granules (from some industrial oxidation reactor)

I had to depart from chemistry for family reasons, but I am back, so to speak

Here is the reactor in operation, the kanthal wire was brought to dull red, the gas evolution was continuous. I led the gas into ccNaOH sol, after ~10mins and orage precipitate appeared with an intense apple smell. The gas was led into 1ml of ccH2SO4 after ~15mins it charred. I did not try to isolate the acetaldehyde since it would require some -30°C temps.

Hi Magpie, the tap is for letting air in below or above the filament, lack of good mixing of the vapors may cause a mini explosion, that is why I still collecting some nerve to try it.

Another method would be to electroplate copper onto the kanthal and heat up the wire under liquid Et-OH itself. It would be interesting to see what happens, maybe all the heat would go into acetaldehyde synth insted of refluxing the Et-OH.

The setup for this is as simple as this:

Quote: Originally posted by Magpie

My thinking on the bisulfite adduct was to simply place sodium metabisulfite in the pot and reflux away, condensing everything back into the pot. Hopefully the acetaldehyde would form the adduct which might be a filterable solid in ethanol. But if the bisulfite is not soluble in ethanol then this likely would not work. [Edited on 17-3-2015 by Magpie]

IIRC the bisulfite should be used in large excess since it is a reversible reaction.

What about reacting the aldehyde with ammonia wapor in ethyl acetate? When the reaction is done. Cool the slurry and filter the crystals.

Magpie:
Et-OH <=> CH3CHO + H2 it is a reversible reaction, you have to eliminate the H2 to speed things up. Air is a cheap reagent for this purpose

Quote: Originally posted by Jimmymajesty

Magpie: Et-OH <=> CH3CHO + H2 it is a reversible reaction, you have to eliminate the H2 to speed things up. Air is a cheap reagent for this purpose

Does the H2 react with oxygen or is the air just a purge gas?
If just a purge gas replace it with N2 or argon.
---------------------------------------------------------------
I just came back from the lab where I tested the solubility of K bisulfite in absolute ethanol. I placed 1g of the salt in a small flask and then added 5 ml of abs ethanol, then heated to boiling. There was no dissolution. I then added distilled water, 1 ml at a time, then bringing to a boil. It took the addition of 12mL of water before the salt was completely dissolved. I will now repeat this experiment with Na bisulfite (if I can find it in my cabinet) and report back.
--------------------------------------------
Remarkably, under the same conditions, the Na bisulfite only required the addition of 3 ml of water to effect complete dissolution at boiling. I will now attempt to find out how much Na bisulfite, if any I can dissolve in 5ml of abs ethanol, and report back.
-------------------------------------------
Even with boiling and stirring I could not get even 0.13g of Na metabisulfite to dissolve in 5ml of absolute ethanol.




[Edited on 17-3-2015 by Magpie]

[Edited on 17-3-2015 by Magpie]

[Edited on 17-3-2015 by Magpie]

Magpie, air is to remove the H2 (oxidize) from the surface of the catalyst.
Today my curiosity conquered my fear and let air into the reactor through the upper tap, the flow was around 1ml/sec but nothing really happened. The temp on the thermometer was remained 110°C, the gas evolution was about the same, maybe it was not enough to make any change, I will give it another go in the coming days.

This time I went with platinum (+rhodium) catalyst scavenged from a catalytic converter of a diesel car.
The thermometer with this type of catalyst was not read as much as with copper, but what does it tell you? Is the platinum cata better because the reaction without air is slightly endothermic?

Quote: Originally posted by Magpie

--------------------------------------------------------------- I just came back from the lab where I tested the solubility of K bisulfite in absolute ethanol. I placed 1g of the salt in a small flask and then added 5 ml of abs ethanol, then heated to boiling. There was no dissolution. I then added distilled water, 1 ml at a time, then bringing to a boil. It took the addition of 12mL of water before the salt was completely dissolved. I will now repeat this experiment with Na bisulfite (if I can find it in my cabinet) and report back. -------------------------------------------- Remarkably, under the same conditions, the Na bisulfite only required the addition of 3 ml of water to effect complete dissolution at boiling. I will now attempt to find out how much Na bisulfite, if any I can dissolve in 5ml of abs ethanol, and report back. ------------------------------------------- Even with boiling and stirring I could not get even 0.13g of Na metabisulfite to dissolve in 5ml of absolute ethanol.

Hi Magpie, I would have not even considered making it if sciencemadness would not have made it seem easy

I read your post but what about the adduct? Could you isolate any aldehyde with it?

I did some test with ethanol today paving the road to formaldehyde synth, it may be obvious but it give me a lot of idea what should/shouldn't be done with methanol.
The setup was rigged to be able to let air bubble through ethanol and there was a kanthal filament under the liquid to regulate its temp.
Findings:
If the methanol at room temperature no matter how much air you pump through it it will not ignite
If it is warm and you increase the air flow there is always a point when an explosion occur.
If the air flow is constant and the liquid is constantly heated it starts to boil, when the condensation front reach the ignition source it starts to burn without explosion, at this state no matter how much air I pumped through the boiling liquid I could not make an explosion.

So basically you can do anything with the vapors, they are way above the explosion limit of the mixture, of course it is only true for this test device so be careful with your own setup.

Quote: Originally posted by Jimmymajesty

Hi Magpie, I would have not even considered making it if sciencemadness would not have made it seem easy

Quote: Originally posted by Jimmymajesty

I read your post but what about the adduct? Could you isolate any aldehyde with it?

Quote: Originally posted by Jimmymajesty

If the air flow is constant and the liquid is constantly heated it starts to boil, when the condensation front reach the ignition source it starts to burn without explosion, at this state no matter how much air I pumped through the boiling liquid I could not make an explosion.

This sounds like holding a tiger by the tail.

You have developed quite a technology there - well done. I will continue to watch from the door.

Hi, today I've got an idea on how to make acetaldehyde, using copper catalyst. I'll add my drawing below... I think I'll try it, but I need to buy aquarium air pump and hose barb to ground glass joint adapter (I don't know where I'd be able to get one though - size 29/32). I'd be happy for you to let me know what do you think about this setup - do you think it would work?

Thanks



[Edited on 24-5-2015 by xfusion44]



[Edited on 24-5-2015 by xfusion44]

Quote: Originally posted by xfusion44

Hi, today I've got an idea on how to make acetaldehyde, using copper catalyst. I'll add my drawing below... I think I'll try it, but I need to buy aquarium air pump and hose barb to ground glass joint adapter (I don't know where I'd be able to get one though - size 29/32). I'd be happy for you to let me know what do you think about this setup - do you think it would work? Thanks [Edited on 24-5-2015 by xfusion44] [Edited on 24-5-2015 by xfusion44]

Thanks to both of you

@hawkguy

I'm a little bit confused now. I thought that ethanol would produce acetaldehyde, and acetone something else? Do they both produce acetaldehyde? Otherwise, I don't think that there would be a lot of acetone in acetaldehyde, because I would not boil it during this process, I'd just leave it to evaporate slowly and efficiently - am I wrong?

@Magpie

I also thought about possible explosions, but haven't yet come up with idea about how to minimize the risk. Probably one would just need to accept the risk when performing this - safety equipment would be necessary here.

BR, xfusion

Quote: Originally posted by xfusion44

I also thought about possible explosions, but haven't yet come up with idea about how to minimize the risk.

Quote: Originally posted by xfusion44

Probably one would just need to accept the risk when performing this - safety equipment would be necessary here.

If you want to try something quick and dirty, I would suggest this configuration over doing it in a jar.



The wad of copper wire on the left is intended to function as a flame arrester. It should stay cool during normal operation in order to provide this function. The copper wire on the right is a wad of very fine wire (to provide as much surface area as possible). These wads of wire are pushed down into the glass tube, which is then bent appropriately with a propane torch. The left side goes into a rubber stopper in an Erlenmeyer flask that contains ethanol. The ethanol is heated slightly in a warm water bath to increase its volatility. In the same stopper, a glass tube is pushed under the ethanol surface, and air is slowly bubbled through. This forms a fuel/air mixture. During operation, the copper on the right can be heated gradually with a propane torch. If the fuel/air mix is correct, the copper will glow even when the torch is removed. This is kind of fun to look at in the dark.

Just because it is safer than doing it in a large jar doesn't mean it is completely safe. Certainly use a face shield. Leather welding gloves are a good idea if it is necessary to adjust things during operation. Even better, a Plexiglas blast shield can be added for extra safety.

@WGTR

Thanks for the idea

Does it work well? Where does the right side of the tube go? To the condenser? How about efficiency?

BR, xfusion

Quote: Originally posted by xfusion44

Thanks to both of you @hawkguy I'm a little bit confused now. I thought that ethanol would produce acetaldehyde, and acetone something else? Do they both produce acetaldehyde? Otherwise, I don't think that there would be a lot of acetone in acetaldehyde, because I would not boil it during this process, I'd just leave it to evaporate slowly and efficiently - am I wrong? @Magpie I also thought about possible explosions, but haven't yet come up with idea about how to minimize the risk. Probably one would just need to accept the risk when performing this - safety equipment would be necessary here. BR, xfusion

Quote: Originally posted by xfusion44

@WGTR Thanks for the idea Does it work well? Where does the right side of the tube go? To the condenser? How about efficiency? BR, xfusion

Quote: Originally posted by byko3y

+1 for question about effectiveness. Catalyst has a limited activity, so there's also a question about whether ethanol should be boiling, or maybe some inter carrier or air is passed through it without ethanol boiling. I think something like 70°C and air will do the job. Because boiling ethanol is hard to control, and higher amount of oxygen will lead to oxidation into CO2.

@Hawkguy

That's exactly why I asked you about using acetone. If the product is the same, it's really better to use acetone because of its lower BP. But when I'm using acetone instead of ethanol, the smell is more pungent and I think, a little bit different, or is it just me?

@WGTR

Thanks!

Looks like you have a lot of experience with acetaldehyde production Well, you could use copper foil in the jar or even copper wool, but as we already know, it's not very safe to do it with the jar method

BR, xfusion

Quote: Originally posted by xfusion44

Thanks! Looks like you have a lot of experience with acetaldehyde production Well, you could use copper foil in the jar or even copper wool, but as we already know, it's not very safe to do it with the jar method BR, xfusion

@WGTR

Thanks! When I try this, hopefully I'll remember to take some pictures

Quote: Originally posted by WGTR

I'm just going to post this reference for right now; it seems very detailed and useful. I don't think it's been posted before. The Catalytic Partial Oxidation of Ethyl Alcohol in the Vapor Phase

Quote: Originally posted by nux vomica

Hi im working on a pentaerythritol synthesis and i am looking for information if you can calculate the % of acetaldehyde in a solution by using the sodium sulfide method as you would to calculate a formeldehyde solution. I have googled for info but havent had much luck finding any info online. Thanks nux [Edited on 9-12-2015 by nux vomica]

Quote: Originally posted by nux vomica

Yes its a mix of unreacted ethanol and acetaldehyde, I collect the distillate that comes off below 60° c but it would be better to know the % of acetaldehyde in the solution so I can calculate how much to collect , and to check purity of the final product.

Quote: Originally posted by Hawkguy

Quote: Originally posted by nux vomica   Yes its a mix of unreacted ethanol and acetaldehyde, I collect the distillate that comes off below 60° c but it would be better to know the % of acetaldehyde in the solution so I can calculate how much to collect , and to check purity of the final product. Try making paraldehyde and measuring it that way

Quote: Originally posted by nux vomica

Quote: Originally posted by Hawkguy   Quote: Originally posted by nux vomica   Yes its a mix of unreacted ethanol and acetaldehyde, I collect the distillate that comes off below 60° c but it would be better to know the % of acetaldehyde in the solution so I can calculate how much to collect , and to check purity of the final product. Try making paraldehyde and measuring it that way I will have to look into that method, as I already use the sodium sulfide method with my formaldehyde solutions I was hoping it wold work with acetaldehyde as well.

Nice going nux! Please give us the details on this preparation including purification and the yield.

I love seeing use of the peristaltic pump, and have noted your fine homemade mantle.

Also, did you make those joint clips? I want some of those for high-temperature reactions. What kind of wire did you use? Anything special or just coat hanger wire?

[Edited on 13-9-2016 by Magpie]

Quote: Originally posted by Magpie

Nice going nux! Please give us the details on this preparation including purification and the yield. I love seeing use of the peristaltic pump, and have noted your fine homemade mantle. Also, did you make those joint clips? I want some of those for high-temperature reactions. What kind of wire did you use? Anything special or just coat hanger wire? [Edited on 13-9-2016 by Magpie]

Quote: Originally posted by nux vomica

I find i use the peristaltic pump more than a dropping funnel as long as the silicon tube can take the liquid flowing through it.

Quote: Originally posted by nux vomica

I got the clips off ebay after the plastic ones kept melting or cracking.

Ive uploaded another video showing the purification of the acetaldehyde and the yield.
https://youtu.be/-x_lMokdjxk

Quote: Originally posted by Magpie

Very nice. I like the simplicity. Does the CaCl2 absorb water? Are azeotropes a concern? Did you have a lot of bumping? I have tried that method for making butyraldehyde and propionaldehyde without much success(per Brewster). But CaCl2 was not used. I will definitely be trying this.

thanks magpie I got the information out of a book on google books




The calcium absorbs the water and seem to smooth the boiling out.
As I understand it there isn't a azeotrope with water or ethanol so separation is reasonably straight forward.

Cheers nux.

I found a intresting occurrence happening in the storage bottle that my Acetaldehyde is kept in, there seems to be crystals of some sort forming on the walls of the bottle , i can only presume that metedehyde is forming and i wonder if a tiny amount of Sulfuric Acid has somehow contaminated the bottle and has catalysed some of the Acetaldehyde.

Quote: Originally posted by tsathoggua1

Here is a thought The tetramer of acetaldehyde is readily available. Metaldehyde is the tetramer, paraldehyde the trimer (nasty shit, really, really nasty stuff, its in some of my physician's books dating back from the 1700s as a sedative-hypnotic. My advice is not to try it, you will thank yourself. Its awful in vivo, it stinks and it eats some plastics, not sure which will resist it, but like chlormethiazole, its quite aggressive towards plastics vulnerable to it) Metaldehyde is the active ingredient in slug pellets. Slugs ingest or absorb it through skin contact and its transformed in vivo to acetaldehyde which poisons the molluscs in question. Two ideas-attempting depolymerization with either conc. or dilute sulfuric acid. Or thermal depolymerization. I'll give it a try, since I've a large tub of slug pellets in the lab courtesy of meaning to try exactly that. I won't use them on the garden, since it would poison other creatures eating the dead slug/snails, and in any case, I'd sooner they eat the plants than kill them. First, I'll try a simple thermal depolymerization of powdered slug pellets in an alembic leading any vapours into an ice-diethylene glycol/CaCl2 bath cooled collection vessel and see what happens. If no luck, then will try addition of a little sulfuric. Anybody know if acetaldehyde attacks plastics? Should be easy to separate acetaldehyde from any paralydehyde, since the BP of the latter is 124'C

Quote: Originally posted by tsathoggua1

I was thinking keep it simple, and do a destructive distillation on the powdered pellets, soaked in a little sulfuric.

Try in small quantity first...and see if it works...
Such a test is cheap and fast...so I would say go for it

I also have bought the product and stocked some at home just in case a few years ago...too bad I didn't did this before the % reduction .

[Edited on 19-2-2017 by PHILOU Zrealone]

Quote: Originally posted by unionised

Slug pellets and dilute sulphuric acid might turn out to be a better synthesis of furfural than ethanal.

Acetaldehyde by pinacol rearrangement?