Sciencemadness Discussion Board

Acetaldehyde synthesis

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bbartlog - 16-10-2013 at 09:10

In my experience a caramel odor is often a tell-tale of formate salts or very dilute formic acid.

Dakin's original experiments did not exclude oxygen, indeed as I recall he sparged his solution with air in order to speed the removal of the acetaldehyde that was formed. But his reaction was conducted at or around 40C. It's also possible that ammonium lactate is less dissociated than other lactate salts and that this would affect the speed of various competing reactions.

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.

WGTR - 16-10-2013 at 09:37

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.


Is this what you are referring to?

http://www.jbc.org/content/4/1/91.full.pdf

http://www.jbc.org/content/1/2/171.full.pdf

http://www.jbc.org/content/4/2/227.full.pdf

[Edited on 16-10-2013 by WGTR]

[Edited on 16-10-2013 by WGTR]

bbartlog - 16-10-2013 at 10:37

Interesting. Yes and no; clearly that is the reference I gave (well, the second one is), and it's mostly on topic, yet none of those three is exactly the paper I remember. Maybe someone other than Dakin did the first piece of work. I'll have to backtrack through the references he gives when I have some time and see whether I can turn it up. It's definitely from that era.

WGTR - 28-3-2014 at 17:50

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

Steam - 29-3-2014 at 05:41

Just made acetaldehyde using Rhodium's method. Got (what looks like) a good yield of acetaldehyde and possibly a slight amount of ethanol. I am too lazy to form the trimer for purification, so I just dried it and called it a day!

http://www.erowid.org/archive/rhodium/chemistry/acetaldehyde...

DoctorZET - 12-4-2014 at 14:01

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 :)

DoctorZET - 12-4-2014 at 14:10

also I know an other good method to make the epoxide of ethylene in large quantities and in a relative small amount of time... but is much more complicated and involve an other intermediate : 2-chloroethanol (Cl-CH2-CH2-OH)...

Crypto - 15-4-2014 at 12:47

DoctorZET can you elaborate a bit on your method? What setup have you used and how have you prepared the catalyst?

DoctorZET - 17-4-2014 at 09:55

Here is a process of making acetaldehyde:

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Crypto - 17-4-2014 at 12:07

After reading the whole thread I must say that the above procedure seems to be the most practical for an amateur chemist. One could prepare the aldehyde practicly in any needed quantity during just one run. No toxic chromates are used which is nice and I guess that the catalyst beds could be placed one after another to omit the condensation step.

Thanks a lot Z. How did you deposit the catalyst on it's support?

DoctorZET - 17-4-2014 at 13:22

And here is the another process:



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DoctorZET - 17-4-2014 at 13:40

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 ;)

DoctorZET - 17-4-2014 at 13:46

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 :)

S.C. Wack - 17-4-2014 at 15:59

Sabatier and Senderens did not use copper scrubbers. Bouveault (attached) made an apparatus improvement going vertical, and used rolls of copper gauze coated with reduced copper, from the hydroxide and hydrogen at 300C.

Attachment: Bull_soc_chim4_3_119_1908.pdf (556kB)
This file has been downloaded 678 times


Oxirane - 1-11-2014 at 13:03

I am planning to do some acetaldehyde in the future. My plan is to drop ethanol into steel tube with dropping funnel to control the feed rate. This vapor will go to SS or glass tube that is packed with catalyst and heated to 300-400C with hot air gun.

Catalyst would be prepared by dissolving copper sulfate into water and mixing silica gel crystals, stirring and filtering out and drying and then pre-heating to decompose the sulfate into oxide with gas flame. This oxide will be flushed with ammonia or hydrogen right prior to use to generate active copper catalyst. This ensures maximum catalytic surface.

Unreacted ethanol will be condensed into first flask fitted with condenser. Flask stands in water and reflux condenser both are kept at 20C. Acetalhdehyde vapors will go over this and condense to next one, where flask is immersed in ice bath with reflux column circulated with same water and insulated to keep it cool as long as possible. From this end an exhaust tube is lead away safely if anything that does not condense comes over.

My idea is that this same setup could be used to produce also formaldehyde and diethyl ether. Ether can be made with Al2O3 catalyst from ethanol, but cannot remember temperature right now. Formaldehyde would be bubbled into cold water which is placed into second flask but otherwise the setup will be the same for all these three.

CuReUS - 3-11-2014 at 04:57

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]

Metacelsus - 3-11-2014 at 07:56

Nitroethane is even harder to get than acetaldehyde.

Oxirane - 3-11-2014 at 15:04

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.

By the way, on the topic, is it possible to catalytically oxidize acetaldyde to acetic acid? I've read on it somewhere and I remember the process is similar to dehydrogenation, but oxygen is introduced to the reactor aside acetaldehyde. But I see there a risk of self-ignition since the reactor conditions are sufficiently hot for that.

[Edited on 3-11-2014 by Oxirane]

WGTR - 3-11-2014 at 18:58

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):

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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.

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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.

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WGTR - 3-11-2014 at 19:18

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.

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

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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.

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[Edited on 11-4-2014 by WGTR]

Magpie - 4-11-2014 at 12:42

I like the way you built the coiled furnace.

You say the beads don't work too well. Have you thought about making a catalyst bed out of a highly porous inert material like pumice or other volcanic rock? I have such a support that I made from pulverized lava rock for barbeques. My pieces are ~ 1/8" in diameter. I soaked them in concentrated H3PO4 and they are now drying in a desiccator. My intent is to use them to produce dry formaldehyde gas from (HCH=O)3. It's a project that's been on hold for some time. My intent is to use the dry formaldehyde to make primary alcohols via a Grignard reaction.

[Edited on 4-11-2014 by Magpie]

Oxirane - 4-11-2014 at 15:57

Copper hydroxide seems to decompose at such low temp as 80C. How efficient it would be if I made a mixture of precipitated copper hydroxide in water and stirred silica gel into it and filtered it so the hydroxide would accumulate to the granules and then dehydrate them by heating for proper copper oxide?

WGTR - 4-11-2014 at 16:17

Thanks, I try to keep things easy if possible.

For some reason I misplaced the reference that I originally used, but here is one with similar information:

Attachment: Effects of Alkaline-Earth Oxide Additives on Silica-Supported Copper Catalysts in Ethanol Dehydrogenation.pdf (126kB)
This file has been downloaded 604 times

The catalyst works fine as far as I can tell. The beads are porous enough that the gasses permeate them easily. When removing freshly reduced catalyst beads from the reactor, they have a dark violet appearance. Cutting them open reveals bright, soft, copper. Problems that I haven't gotten around to solving yet:

1. Vaporizing the alcohol without a carrier gas. I have saturated nitrogen with alcohol vapors in previous tests, and this worked OK. The problem is that I have all the liquid nitrogen a chemist could want, but most other people do not. For this reason I want to keep the vapor phase 100% alcohol. Conversion is lower this way, but the operation is simpler, and the unreacted alcohol can be sent back to the vaporizer.

2. Alcohol likes to condense on things. The boiling liquid alcohol in the vaporizer needs to be the coldest thing in the entire system, except for the output condenser and return line. Under no circumstances can condensed alcohol be allowed to bubble into the reactor inlet, our drip back into the catalyst bed on the outlet. If liquid makes contact with hot catalyst, the catalyst disintegrates. Vaporization needs to be smooth, without liquid alcohol superheating and bumping. The most straightforward way of maintaining a healthy vapor phase would probably be to enclose the entire system in an oven. The catalyst would run at a higher temperature dictated by its own heating element.

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.

Sabatier wrote a great deal on this. I was so impressed with the book that I bought a (new) copy:

http://books.google.com/books?id=qOjQAAAAMAAJ&pg=PA232&a...

CuReUS - 5-11-2014 at 02:17

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.



cheddite,isn't nitroethane sold as dragster fuel.also there is a very good thread on making EtNO2 incase you cant buy it

oxirane ,i didnt understand your comment,are you saying possessing nitroethane is illegal,because it is not on DEA watchlist http://en.wikipedia.org/wiki/DEA_list_of_chemicals

[Edited on 5-11-2014 by CuReUS]

Oxirane - 6-11-2014 at 14:35

I mean that nitroethane is considered a niche product comparable to nitroMethane for most but cookery chemists, who consider it as a valuable precursor. Nothing more to add on this subject.

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.


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

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?

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.

[Edited on 6-11-2014 by Oxirane]

WGTR - 6-11-2014 at 21:10

First of all, I would strongly encourage anyone who wants to work with alcohol dehydrogenation, or catalysis in general, to read the Google Books link that I posted at the end of my previous post. The book was written by Sabatier, and I think of him as the grandfather of catalysis. The book is free to download. I lot of what I have learned, I learned from this book.

Quote: Originally posted by Oxirane  

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


The decomposition has more to do with catalyst activity than bed size. Copper is the active catalytic material, and its activity varies according to how the catalyst is prepared. Copper hydroxide, gently reduced at the lowest possible temperature (250-300C), will take on a dark violet coloration. This is a very active form of copper, as it has very high surface area. It works well for ethanol dehydrogenation, but is too aggressive for methanol. Copper hydroxide that is dead-burned (as the oxide) at prolonged read heat will have much less surface area. It is too sluggish for ethanol, but works OK for formaldehyde production. Upon reduction it will usually have a bright copper color.

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?


Nitrates are strong oxidizers, especially when heated to 450C. In the presence of reducing agents they won't last long at high temperatures.

I haven't tried the exact procedures outlined in that journal article. It's possible that the silica support helps the catalyst maintain activity even after heating to high temperatures. Fine copper powder (as mentioned above) actually works fine for dehydrogenation. The main reason that other elements are used is to minimize catalyst deactivation. Prolonged heating of fine copper in a reducing environment will eventually sinter the copper into a low surface area material. This may take several hours, and may not be a problem for non-industrial processes. I'm using copper/magnesium oxides in my tests. The magnesium oxide helps the catalyst maintain activity over a longer period of time that copper alone. As I mentioned before, I haven't re-found the exact reference that I pulled this idea from. It was a journal article.

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.


Just prepare the catalyst the way that I did earlier, and that should be an easy start. The catalyst doesn't need to be protected from air. It will oxidize, but it will immediately be reduced again once alcohol vapor is passed over it. I never use hydrogen to reduce the catalyst. Alcohol vapors work just as well.

For methanol dehydrogenation, copper pipe may work as long as it has been oxidized and reduced a few times on the inside. It may take considerably higher temperatures with that type of catalyst, though. Read through the book for more explanation on this.

Oxirane - 7-11-2014 at 00:01

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.

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WGTR - 7-11-2014 at 08:27

Sodium hydroxide reacts with silica gel to some extent, forming silicates. Otherwise, you'll have to try it and see.

Pure copper is very soft. Unoxidized nano-copper can be smeared into a copper streak at room temperature. At higher temperatures this occurs more readily. When milling copper, I've seen the warm copper chips immediately weld themselves to the work-piece while I cut. This is caused by a combination of warmth, an extremely clean surface, and pressure. Gold does the same thing. It is so soft and inert that it can be hammered into one piece without heating. According to the book, 300C is about the highest temperature that one wants to go with a pure copper catalyst, as the copper rapidly loses surface area above this temperature.

[Edited on 11-7-2014 by WGTR]

Oxirane - 9-11-2014 at 02:51

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. :D

NitreRat - 8-3-2015 at 04:48

I've thought of a potentially OTC method that I haven't seen mentioned yet.
Dehydrohalogenation of dichloroethane to vinyl chloride gas followed by nucleophilic substition to vinyl alcohol which rearanges to acetaldehyde.

1. C2H4Cl2(l) + NaOH(al) -> C2H3Cl(g) + NaCl + H2O
2. C2H3Cl(g) + NaOH(aq) -> C2H3OH + NaCl
3. C2H3OH -> CH3CO

This method only uses dichloroethane (a fairly common solvent and easily made from ethylene glycol), sodium hydroxide and an alcoholic solvent. It also can be done with fairly basic glassware.
The main drawback I can see is the highly toxic nature of vinyl chloride gas. Thoughts?

Jimmymajesty - 14-3-2015 at 13:19

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.


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WGTR - 14-3-2015 at 17:20

That's some nice glassware. I'm jealous!

I had always wondered what happened to you. I had followed your experiments in this thread back in the day, and tried some of them myself. I hadn't noticed your posts in the last year.

As an FYI, Teflon-insulated stranded wire uses silver-plated copper strands. I took an individual thin strand, wound it into a double-helix, and found that it didn't take too much current to get it to heat up.

I have personally gravitated towards using a tube furnace configuration with catalyst beads, since that is easy for me to build. What I have never done very well is the acetaldehyde condensation and separation from the excess alcohol. I haven't put the necessary time into fine tuning this process.

So, is the reactor intended to work horizontally? And, did you make it yourself?

[Edited on 3-15-2015 by WGTR]

Jimmymajesty - 15-3-2015 at 01:28

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:)

Jimmymajesty - 15-3-2015 at 11:21

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.



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Magpie - 15-3-2015 at 14:35

That's an interesting looking apparatus, Jimmy. What is the side tap with the stopcock for?

I haven't read this thread but I'm wondering if forming a bisulfite adduct of the acetaldehyde in situ would be a good way to isolate it.

Edit: I skimmed through to page 9 where I found your link to Len1's method for benzaldehyde where he purifies with the bisulfite adduct. I don't know how this would work out for acetaldehyde, however.

[Edited on 16-3-2015 by Magpie]

Jimmymajesty - 16-3-2015 at 13:38

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:


IMG_3605.JPG - 548kB

Magpie - 16-3-2015 at 14:12

I'm really not up to speed on this thread or any reading on making acetaldehyde but I have made/attempted to make propionaldehyde and butraldehyde by oxidizing the alcohols per Brewster. My yields were poor or non-existent.

Why do you have to introduce air? Doesn't the ethanol supply the oxygen for the -CHO? I like your simplified apparatus, though.

CH3-CH2-OH -----> CH3CH=O +H2

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]

WGTR - 16-3-2015 at 20:17

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]


That's an interesting idea. I can't say that I ever thought of that one before. A previous post by Nicodem may answer your question:

http://www.sciencemadness.org/talk/viewthread.php?tid=6118&a...

I don't know if steam would have any affect on alcohol dehydrogenation. It may actually help it, by diluting hydrogen in the reaction products, and preventing alcohol dehydration. I don't think dehydration is a significant problem with copper catalysts, though.

Magpie - 17-3-2015 at 08:14

Thanks for that good information WGTR. This gives some hope for the method and may justify some experimentation. I see another potential problem, however: assuming that the adduct can be made and removed by filtration now it must be reacted with NaOH to recover the aldehyde. Without reading to find out why I understand that this harms the aldehyde. Cannizzaro reaction perhaps? However, I know that other aldehydes are recovered this way.

Jimmymajesty - 17-3-2015 at 12:03

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:)

Magpie - 17-3-2015 at 13:30

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 :o 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]

Jimmymajesty - 19-3-2015 at 14:21

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?



IMG_3606.JPG - 615kB IMG_3608.JPG - 517kB

Magpie - 19-3-2015 at 15:23

Jimmy, I did a little more reading of this thread and now realize how much work you have done. You probably know more about this synthesis than anyone else on this forum.

I did read in Gattermann (1937) in the forum library that making acetaldehyde-ammonia, a solid, is a practical way to store it, as is making metaldehyde. His procedure looks quite long and complicated.

I really have no plans for making it, although I would like to have some for making crotonaldehyde.


Jimmymajesty - 23-3-2015 at 09:36

Magpie, any luck with the bisulphite method?

I did a two hours run and collected ~20ml, it started to boil by simply holding the glass in hand. Maybe let the vapor onto dry ice is the only option since the refrigerator was ~-10°C still the acetaldehyde smell was as pungent as without the fridge.

I also did a run with methanol, there was not any formaldehyde present. I realized when I came home that there should not be any, since the CH3-OH requires oxigen surplus to be oxidized and on Pt it tends to go till H2O+CO2.

I hoped to be able to co-oxydize Me-OH with Et-OH to get their aldehydes in the same mixture, but you would need 1-2gMe-OH in 2litres of air to get the oxidation going.

Anyway the Me-OH is a good hydrogenating reagent in this setup (CH3-OH => CO + 2H2) and I think with copper it could reduce many things like NO2 groups to NH2

Magpie - 23-3-2015 at 10:19

Nice going Jimmy. You may be the only person on this forum to successfully make acetaldehyde in any significant quantity. Well done.

Did you miss my report from an earlier post? See below.
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.

Jimmymajesty - 24-3-2015 at 13:17

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.



IMG_3624.JPG - 542kB

Magpie - 24-3-2015 at 13:56

Quote: Originally posted by Jimmymajesty  
Hi Magpie, I would have not even considered making it if sciencemadness would not have made it seem easy:)


Yes! There is no limit to what we can do. It's only a matter of time.

Quote: Originally posted by Jimmymajesty  

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


I'm presuming that since ethanol is the feedstock for making acetaldehyde, and I could not get the bisulfite to dissolve in ethanol, it would be of no use for your synthesis. But once you make the acetaldehyde I would certainly think that you can add it to the product mixture and form the aldehyde adduct, a solid. I have used it this way before, successfully. It's a commonly used technique.

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. ;)




clearly_not_atara - 26-3-2015 at 11:53

Two methods not tested:

* Oxidative decarboxylation of lactic acid by bromine water: there's an entire PhD thesis discussing the mechanism of this particular reaction (alpha-hydroxyacids and aqueous Br2) which is probably helpful. Bromoacetaldehyde, a lachrymator, may be produced in some amounts as a byproduct, which is the major downside of this route. However in general acetaldehyde should boil away as quickly as it is formed if the reaction is somewhat warm, and bromine isn't fun to breathe either.

* Triketone Strecker degradation of alanine by dehydroascorbic acid or alloxan; the former is produced by oxidizing ascorbic acid (various possibilities: H2O2; MnO2; etc), the latter by oxidizing uric acid with nitric acid. Alloxan ingestion causes permanent diabetes, so don't. Dehydroascorbate is unstable and must be produced in situ; it is stabilized by acidic conditions.

* Hypochlorite Strecker degradation of alanine; similar to the above but may produce chloroacetaldehyde as a byproduct.





[Edited on 26-3-2015 by clearly_not_atara]

Jimmymajesty - 27-3-2015 at 15:43

Magpie, the tiger did not bite! I did a run today with methanol (Cu catalyst), I let air in below and above the filament also, honestly I did not notice the difference, there was a strong smell of HCHO in both cases.

c n atara I read somewhere that alloxan forms in food that is bleached, like flour and some sugars also.. so like it or not we eat it anyways

Magpie - 27-3-2015 at 15:57

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

gboneu - 12-5-2015 at 13:41

When i was using at som TCCA (Trichloroisocyanuric acid) which is used in pools as Chlorine tablets, When i used Ethanol with this in over 5 min. A student reaction occurred and my lab was smelling Acetaldehyde .xD So i believe that controlling the Temperature might me the trick and you can use it, Though you mey need a catalyst because a little of anhydrous oxalic acid was present and the ethanol wal 99,5% (Anhydride) You can try ir out with 95% ethanol, and no Oxalic acid.
NOTE: I didn't heat the reaction, it just went by it's self

[Edited on 12-5-2015 by gboneu]

xfusion44 - 24-5-2015 at 07:05

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]

IMG_20150524_165659.jpg - 1.5MB

[Edited on 24-5-2015 by xfusion44]

Hawkguy - 24-5-2015 at 07:36

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]
That looks like a pretty good method as for affordability. Keep in mind however that you will also end up with a lot of Acetone in your product, so it will likely have to be purified extensively. You shouldn't need a ground glass adapter for the tube to condenser, use a cork fitted with thevtube. And push that into the socket. Nice

Magpie - 24-5-2015 at 07:39

Beautiful sketch!

What's to prevent a fire (explosion) in that jar?

As the previous commenter said you will have by-products like acetone and unreacted ethanol in the condensate. How will you separate them from the acetaldehyde?

xfusion44 - 24-5-2015 at 08:31

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

Magpie - 24-5-2015 at 09:13

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.


see: http://www.sciencemadness.org/talk/viewthread.php?tid=55&...

(post of organikum)

Also, see jimmymajesty's fine work, this thread

Quote: Originally posted by xfusion44  

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


I'll be standing at the door with a face shield on.

No, I would not do this experiment unless first convinced I would not have an explosion.

xfusion44 - 24-5-2015 at 09:38

@Magpie

Thanks!

Maybe you could just press the lid on top of the jar and seal the gap with PTFE - this should act as a safety valve, so that in case of explosion it would just blow the lid off of the jar.

[Edited on 24-5-2015 by xfusion44]

WGTR - 24-5-2015 at 16:39

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

IMG_1107.JPG - 900kB

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.

xfusion44 - 25-5-2015 at 01:53

@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

byko3y - 25-5-2015 at 02:40

+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 - 25-5-2015 at 06:52

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


Sorry, I thought you were doing the reaction with Acetone. Thats the way I've done it before, because of its boiling point, and I haven't had any explosions with it like I have with Methanol or Ethanol..

WGTR - 25-5-2015 at 09:30

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


No, it does not work very well. Yes, the right side of the tube goes to a condensor. The efficiency (or my patience) was poor enough that I couldn't get quantitative amounts of acetaldehyde from it. At the same time, it will be more effective than a copper spiral in a jar, and much safer. It will also give an idea of how air flow and fuel mixtures affect its general operation. And yes, one can smell some pretty pungent products coming out the other end.

Now, to explain the previous a little better: Temperature control was very difficult with this setup. Yes, the initial heating was accomplished with a torch. However, the thin wire of the catalyst offered poor heat transfer, so localized overheating would occur during operation. The bulk of the wire catalyst was not used evenly. Most of the reaction would occur at one localized area in the bulk wire, usually at the leading edge. The self-sustainability of the reaction was determined by the air-fuel ratio. This in turn was determined by the alcohol temperature and the effectiveness of the air bubbler. As byko3y mentions, it is easy to overoxidize the product.

The air volume was very low. I would estimate about 1 cm^3 per second, but that is probably too fast for this particular setup. When one considers the low air flow involved and that alcohol vapor is a only small fraction of this, it's not surprising that one will wait a very long time for that first mL of acetaldehyde. In "Catalysis in Organic Chemistry" (Sabatier) pg. 654, a column full of copper catalyst 25-30mm in diameter, 1 m in length was used to prepare 500g of acetalydehyde per day. That gives an idea of how slow this process can be.

I gave up on the idea of oxidative dehydrogenation, and instead focused on direct dehydrogenation. The latter process requires the continual addition of heat to continue, so it is less likely to overheat. It also avoids the use of oxygen, so the products are free of acetic acid, water, etc. I detailed the construction of this idea here:

https://www.sciencemadness.org/whisper/viewthread.php?tid=55...

Also, JimmyMajesty's setup is quite impressive, and works on similar princicples. He has done well with the output condensor design, which is something I have yet to do properly. The acetaldehyde product will contain a large amount of unconverted ethanol. For this reason it is always necessary to seperate out the ethanol from the products, and send it back to the boiler. The condensor will need to be able to separate out this alcohol from the acetaldehyde, and also to efficiently condense out the aldehyde. This is easier said that done, as one can see when reading back through JM's posts in this thread.

I would strongly advise reading through Sabatier's book on catalysis. It was such an instructive and interesting book, that I almost read it cover-to-cover in one sitting. It is available for free all over the internet. It will help you more than I possibly could in a thread.

That is a nice drawing, by the way.

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.


The temperature I was using was about 40-60C. It has to be adjusted to change the air-fuel ratio. I would generally get the alcohol concentration as high as I could, while it would still allow a self-sustaining reaction in the catalyst.

xfusion44 - 26-5-2015 at 04:42

@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 :D

BR, xfusion

WGTR - 26-5-2015 at 20:41

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 :D

BR, xfusion


You're welcome! There's more than one way to do things like this. I think that JimmyMajesty's setup has been the most practical overall, as he has made the most here using direct dehydrogenation (as far as I know).

Certainly, as you try things out, post pictures and ask questions if needed. I enjoy seeing people's practical setups on this topic.

xfusion44 - 28-5-2015 at 06:09

@WGTR

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

Hawkguy - 18-6-2015 at 16:57

Hey if Aldehyde/ Ketones can be collected by a destructive distillation of a corresponding Calcium salt, can Acetaldehyde be produced from Calcium Acetate?

gdflp - 18-6-2015 at 17:22

No, you don't get acetaldehyde, you get acetone. http://www.sciencemadness.org/talk/viewthread.php?tid=16216 It was suggested earlier in this thread, but calcium formate is required as well and yields are pathetically low. http://www.sciencemadness.org/talk/viewthread.php?tid=55&...

Hawkguy - 18-6-2015 at 20:40

Rats I thought I found an easy shortcut. Well, back to the Dichromate style oxidation then.

clearly_not_atara - 2-8-2015 at 15:14

From Advanced Organic Chemistry, Fieser & Fieser, (c) 1961, found at a used book sale (^,^):

12.6 - Tosylate method - Kornblum found (1959) that primary saturated alcohols are converted into aldehydes in 60-85% yield by oxidation of the tosylates with dimethyl sulfoxide (DMSO) in presence of sodium bicarbonate at 150C. Benzylic tosylates are oxidized smoothly at 100C. The required esters can be produced from the halides; for example, by reaction of n-octyl iodide dissolved in acetonitrile with silver tosylate.

Ethyl halides might be more reactive than octyl, so the iodide might not be necessary... also if you have tosyl chloride or even [m]ethanesulfonyl chloride you're probably set. Ethyl tosylate can also be prepared by the reaction of ethyl orthoformate with toluenesulfonic acid and fractional distillation.

https://www.erowid.org/archive/rhodium/chemistry/sulfonic.es...

Silver tosylate can be prepared by salt metathesis from silver nitrate and sodium tosylate; AgOTs precipitates. See:

http://onlinelibrary.wiley.com/doi/10.1002/047084289X.rs030/...

Be aware: the autoignition temperature of acetaldehyde is 185 C. Don't blow yourself up. But ethyl tosylate is more reactive than longer alkyls thus shouldn't have to get so hot.

[Edited on 2-8-2015 by clearly_not_atara]

S.C. Wack - 14-11-2015 at 18:05

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

Without the googly part, that's
https://www.ideals.illinois.edu/bitstream/handle/2142/4460/e...

There is also the earlier
https://www.ideals.illinois.edu/bitstream/handle/2142/4543/e...

Related paperwork using copper turnings, etc. (formaldehyde is also made from methanol)

Catalytic Partial Oxidation of Alcohols in the Vapor Phase—III
W. Lawrence Faith, D. B. Keyes
Ind. Eng. Chem., 1931, 23 (11), pp 1250–1253
DOI: 10.1021/ie50263a014

Catalytic Partial Oxidation of Alcohols in the Vapor Phase.IV
W. Lawrence Faith, P. E. Peters, D. B. Keyes
Ind. Eng. Chem., 1932, 24 (8), pp 924–926
DOI: 10.1021/ie50272a022

Attachment: ie50263a014.pdf (145kB)
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Attachment: ie50272a022.pdf (161kB)
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[Edited on 15-11-2015 by S.C. Wack]

nux vomica - 9-12-2015 at 15:42

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]

Hawkguy - 9-12-2015 at 16:11

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]


What would the Acetaldehyde be dissolved in... Ethanol?

nux vomica - 9-12-2015 at 16:21

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.

Hawkguy - 9-12-2015 at 16:25

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

nux vomica - 9-12-2015 at 16:36

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.

Hawkguy - 10-12-2015 at 16:17

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.


What's nice about doing it this way is that you lose no product during the testing.

nux vomica - 10-12-2015 at 18:08

I ran another batch last night and ended up with 60mls of acetaldehyde ethanol mix I will try your suggestion if I can tonight thanks nux.

Daffodile - 9-3-2016 at 20:46

Huh I found a patent that said Acetaldehyde can be prepared by dry distilling/ pyrolyzing Barium Formate. Might be interestng to anyone looking for alternate routes to such a product.

EDIT: I'm reading old SM threads on the topic, and I can't get a consistent answer, some say the pyrolysis produces Acetone or Formaldehyde.


[Edited on 10-3-2016 by Daffodile]

clearly_not_atara - 23-3-2016 at 14:22

Both quotes from page 2:

Quote:
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.


Quote:
the condensed chemical dictionary states that pyruvic acid is derivated by dehydration of tartaric acid by distilling with potassium acid sulfate so both decarboxilation and pinacol rearrangement happen in this reaction.


Both from page 2. I noticed that the mechanisms of these reactions are all acid-catalyzed, and in fact are all catalyzed by H2SO4. Tartrate undergoes a pinacol rearrangement to oxaloacetate, which decarboxylates to pyruvate, which decarboxylates to acetaldehyde. Why not simply heat tartaric acid in sulfuric acid?

clearly_not_atara - 28-3-2016 at 11:48

http://www.organic-chemistry.org/abstracts/lit3/684.shtm

Selective, aerobic, uses catalytic 4-hydroxy-TEMPO, ferric nitrate, sodium chloride, and silica. Would've edited this into my last post but I can't and this reaction looks frankly amazing from an atom economy and safety standpoint.

[Edited on 28-3-2016 by clearly_not_atara]

nux vomica - 12-9-2016 at 19:15

Link to youtube video https://youtu.be/7XNoWUeWxIk

Magpie - 12-9-2016 at 19:47

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]

nux vomica - 12-9-2016 at 20:19

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]


Thanks magpie i am going to do some more work on the purification tonight so i can post some more info .

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.

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

[Edited on 13-9-2016 by nux vomica]

Magpie - 13-9-2016 at 08:58

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.


I replaced the silicone tubing with a smaller PVC (Tygon) tubing. It works just as well or better as the ID is smaller.

Quote: Originally posted by nux vomica  

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


I tried to make those out of coat hanger wire but it is too stiff.

nux vomica - 14-9-2016 at 19:10

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



20160913_182448.jpg - 793kB

20160913_191508.jpg - 643kB

Magpie - 14-9-2016 at 22:08

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.

nux vomica - 14-9-2016 at 22:39

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


Capture 2.PNG - 42kB Capture.PNG - 45kB

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.

nux vomica - 26-9-2016 at 23:53

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.

20160927_173827.jpg - 489kB

clearly_not_atara - 17-11-2016 at 13:40

Found this by accident, no really:

https://books.google.com/books?id=Cbc2AAAAQBAJ&pg=PT1830...

Quote:
Oxidation of alcohols with NaOCl can also be performed in the absence of nitrosyl radicals or a transition metal by the addition of certain promoters such as phase transfer catalysts, beta-cyclodextrin, or the use of an ionic liquid as solvent. The PTC/NaOCl protocol has emerged as the most convenient method of choice. A distinct advantage of the PTC/NaOCl protocol relative to the NaOCl/AcOH procedure is the ability to oxidize primary alcohols to aldehydes with minimal overoxidation to the ester, and the ability to oxidize alcohol substrates selectively in the presence of double bonds. In addition the PTC conditions do not require the use of chlorinated solvents and often afford fast rates of reaction at ambient temperature.


It appears that the likely mechanism of the hypochlorite/PTC oxidation is the electrophilic addition of the alcohol to hypochlorite ion:

RCH2OH + OCl- >> OH- + RCH2OCl (slow)

This is deprotonated by hydroxide, which is extremely basic in aprotic solvents:

RCH2OCl + OH- >> RCHOCl- + H2O (fast) [solvent cage effect]

and eliminates chloride:

RCHOCl- >> RCHO + Cl- (fast)

The aldehyde doesn't react further because this intermediate forms:

RCHO + OCl- >> RCH(OCl)O-

which is both much less acidic (negatively charged) and does not generate free hydroxide ion, so the elimination of HCl to form RCO2- is much less favorable.

Examples:

1-octanol + NaOCl [EtOAc/H2O, Bu4NBr] >> 1-octanal (86%)

15-desmethyl-cholesterol + NaOCl [EtOAc/H2O, Bu4NBr] >> 15-desmethyl-cholesterone (72%)

http://www.sciencedirect.com/science/article/pii/S0040403998...

Another version is catalyzed by cyclodextrin (Febreze) and occurs in water:

cinnamyl alcohol + NaOCl [beta-cyclodextrin, water] >> cinnamaldehyde (99%)

The cyclodextrin procedure may be more appropriate for ethanol, actually.

[Edited on 17-11-2016 by clearly_not_atara]

tsathoggua1 - 18-2-2017 at 09:31

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

PHILOU Zrealone - 18-2-2017 at 16:39

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

How much % metaldehyde are present into your pellets?
Here in Belgium the % is relatively low (5-12%)...in the past (20-25 years ago) the % was much higher and that route to obtain ethanal was viable. Why the % reduction? Probably thanks to Europe régulations to fight against poisoning and toxic casualities of humans and animals.

Now with such a low % it is probably better to start from ethanol.

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

tsathoggua1 - 18-2-2017 at 16:51

Fucking politicians. IMO someone needs to come up with 'politician pellets' that can be scattered around where such vermin congregate and off them. At least there would be little collateral damage, given politicians aren't generally a wildlife menu item.

I just grabbed the slug pellets. 3%. Pretty measly, but the container is full more or less, not sure if any have been used but either totally or almost full. I had a go at my old man once and told him to stop putting slug pellets down because of the hedgehogs that are likely to eat the poisonous slugs.

And we do have them round here, I've seen them snuffling around at night. Cute as hell they are, if caught gently in the hands, the distribution of spines is too wide to do damage unless someone were to badly handle them. After a while they start getting a little more trusting and uncurl, start snuffling at your hands.

I took one in years ago too, just a baby, found it in a back alley with winter coming on, there was no way it would have survived hibernation since it was too thin and scrawny. Kept it over winter, fed it up and eventually, released a nicely plump, well-fed fighting fit hedgehog.

I'll try roasting some of those slug pellets, ground up with a little H2SO4 added.

Question-concentration of H2SO4? I have 98% should conc. sulfuric be used or should it be diluted first? and is heating actually necessary?

PHILOU Zrealone - 18-2-2017 at 18:42

Hedgehogs, yes cute and usefull as insect-eaters.
I had also one once a few days...but those are night/nocturne animals...and it was doing such a noise at night that it woke the neightbourgs up....so I set it free quite fast afterwards.

If it is for hydrolysis...there is no need to use too concentrated acid...the acid is a catalyst but the reactant is the water...so without water...it won't work.

Now the real problem is to know what are the 88-97% remaining material...is it compatible with H2SO4, has it a value, on its own or as a derivative...

Maybe you could work on an extraction first...to increase the %...owing to the cyclic ether (acetal) nature of the tetramer...it must be soluble in organic solvents...like benzen or chlorofom...of course if the rest of the material is not soluble into the solvent too.

tsathoggua1 - 18-2-2017 at 19:35

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

PHILOU Zrealone - 19-2-2017 at 06:43

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 :D;):P:)

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]

unionised - 19-2-2017 at 07:59

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

PHILOU Zrealone - 19-2-2017 at 16:19

Quote: Originally posted by unionised  
Slug pellets and dilute sulphuric acid might turn out to be a better synthesis of furfural than ethanal.

Why? Because of the 88-97% remaining unknown material? Is it a pentose/hexose (cellulose or polyose) related material?

tsathoggua1 - 20-2-2017 at 07:13

Cheap? more or less free since I already have the sulfuric, and the the pellets were bought by my old man for killing slugs. I took them, just in case he got tempted to use them, because of the effect on wildlife in part (I am very much an animal lover, and indeed I'd even side with the slugs rather than kill them, I'd just catch them and move them to the garden of somebody I didn't like. And if I see snails in the street when I'm out I'll stop to pick them up and place them at the side of the street or on a garden fence assuming its not sunny and hot. If it is, I put them in the shade under someone's garden plants; to avoid those in the middle of the street being trodden on accidentally, or deliberately for that matter and crushed)

And partly because a lot of me was looking at the jar of pellets and thinking...hmm bet that tetramer of acetaldehyde can be depolymerized and some acetaldehyde had from it!

I don't know what the slug pellet base is,, the bulk filler I mean. I'll give it a crack now once I've finished my smoke and had my morning dose of morphine, chlormethiazole, clonidine, tizanidine and additional oxy.

Edit-slight delay, need to find a spare mains plug for my water pump for the condenser. Also, checking, also found another half to 3/4 full pack of metaldehyde slug pellets, although they are metaldehyde based it doesn't say what percentage is in them or what the base material is either. Plus as a bonus another full pack, but not metaldehyde, ferric phosphate. Which presumably in the anhydrous state is a lewis acid and could be dehydrated using P2O5 as a slurry in some suitable solvent of choice?

[Edited on 20-2-2017 by tsathoggua1]

Acetaldehyde by pinacol rearrangement?

Magpie - 11-3-2017 at 11:13

Does anyone know if acetaldehyde can be made by the pinacol rearrangement of ethylene glycol. If so, would it be practical for the home chemist?

byko3y - 11-3-2017 at 21:53

https://dx.doi.org/10.1016/S0040-4020(02)00103-5 - Ethylene glycol to acetaldehyde-dehydration or a concerted mechanism
https://dx.doi.org/10.1002/(SICI)1099-1395(199910)12:10%3C74... - Hydrogen as a migrating group in some pinacol ­rearrangements: a DFT study
I have no double the reaction is possible, but I have no idea how to perform it. The only thing I'm sure is that you can't get acetaldehyde by heating ethylene glycol in a dillute sulfuric acid.

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