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Author: Subject: Methanol -> methanal
S.C. Wack
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[*] posted on 14-8-2009 at 21:10


Quote: Originally posted by kclo4  
Trioxane is in fuel starter tablets and will produce anhydrous formaldehyde upon heating.


Either that or it will distill unchanged at 115C, one or the other.

WTF does this have to do with oxidation of methanol?




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[*] posted on 15-8-2009 at 05:16


I think he has got the wrong polymer of the wrong aldehyde.
If you heat metaldehyde (which is used as a fuel) it sublimes.
If you heat paraformaldehyde (which isn't used as a fuel as far as I know) you get fromaldehyde
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[*] posted on 17-11-2012 at 19:19


Shouldn't you be able to do simple formaldehyde bubbler to purify paraformaldehyde directly into formaldehyde solutions up to 37% conc.? Shouldn't the formaldehyde solutions be suitable for most purposes (hexamine, pentaerythritol, etc.) used as so?

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[*] posted on 17-11-2012 at 19:46


the easiest way to pure formalin solution, is to take a flask of methanol. Heat gently on sand bath, leading up to platinized asbestos or platinum gauze. All you have to do is warm the catalyst whilst the methanol vapor is consistently flowing over it, and lead the tube into some cold water. I think you'll get a standard 32 or 37% solution near room temp. saturation. After you heat the Pt to the required activation temperature, I believe the RXN is self sustaining, endothermic. Very smooth reaction, very pure product. You could almost as easily make acetaldehyde using everclear.
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[*] posted on 17-11-2012 at 19:56


Snip...

[/rquote]WTF does this have to do with oxidation of methanol?[/rquote] ....Snip

I got nothing against you, Wack, and it's really not my business to comment here. Just, you don't have to be an a-hole if you don't want to. That's all. Or maybe I got you all wrong. Maybe you honestly can't see the connection that although trioxane doesn't have anything to do with methanol, the author's end game was formaldehyde. Now, I bet my money you are smarter than that. So?
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[*] posted on 27-11-2012 at 14:23


Here is an article on the synthesis of formaldehyde from methanol with sodium carbonate as a catalyst at 690 degrees centigrade:
http://infoscience.epfl.ch/record/84560/files/92_Su_ApplCata...

Carbon fibers are used as catalyst support.




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[*] posted on 7-1-2013 at 15:12


I think it was Norris' book on organic chemistry that suggests plainly heating copper rod to very hot and submerging it into methanol. No yields were stated but the simplicity is so pleasing.

I will try it some day (probably not soon) just because it is so incredibly simple :o
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[*] posted on 8-1-2013 at 19:38


It sounds tempting, but it's a very bad idea. Think of how the methanol would burst into flames^^ and how you could get intoxicated by methanol vapours.

I don't see the difficulty in obtaining copper oxide, I have a few grams of the stuff from the decomposition of copper carbonate. If I knew how to, I would have mounted some of it onto a support to make a catalyst, and presto! Formaldehyde synthesis for the amateur.

Just wondering, does anyone know the conditions under which aqueous formaldehyde will condense to paraformaldehyde? I would really like to try this out, but for handling purposes, I would prefer to make trioxane or paraformaldehyde, even if this requires an extra step. Wiki said that paraformaldehyde forms spontaneously in aqueous solution, but I seriously doubt that is an efficient synthesis route.




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[*] posted on 9-1-2013 at 10:53


Quote: Originally posted by SixTough  
I think it was Norris' book on organic chemistry that suggests plainly heating copper rod to very hot and submerging it into methanol. No yields were stated but the simplicity is so pleasing.

I will try it some day (probably not soon) just because it is so incredibly simple :o


I've done this many times, the methanol never ignited but I don't know how many times you need to dunk the copper into the alcohol to have any appreciable amount of anything form. It does make a faint formaldehyde smell though.
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[*] posted on 9-1-2013 at 11:53


I would be interested in knowing more about the oxidation of methanol. I have prepared acetaldehyde by distilling it out of acidified ethanol/dichromate (sulphuric acid), but substitute methanol for the ethanol and very little formaldehyde is formed. why ?.
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[*] posted on 12-1-2013 at 15:25


That's a tough question. Preparing acetaldehyde is already quite a challenge:
http://www.sciencemadness.org/talk/viewthread.php?tid=55

Do you mind providing more details on your procedure for making acetaldehyde? (amounts of reagents used, temperatures, yields, that sort of stuff) I'd be really interested to know.

I might be attempting a synthesis of formaldehyde soon. I'm working out the technical details and trying to find a way to do this safely. The whole process is a bundle of danger; flammables, volatile carcinogens, high temperatures, and hydrogen gas.




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[*] posted on 12-1-2013 at 18:55


Typical procedure, from Hale in SM library: Methyl alcohol (100 ml) is placed in a flask which is kept at a temperature of 40°, and connected to a horizontal combustion tube in which a roll of copper foil (5 cm. long) is placed. The other end of the combustion tube is connected to a condenser and a well cooled receiver.

A stream of air is driven through the alcohol causing a mixture of air and alcohol vapour to pass through the copper coil, which should be heated until it just glows. The reaction will proceed without further heating and a solution of formaldehyde in methyl alcohol will collect in the receiver.

Small explosions on the copper do no harm; but the temperature should not exceed a dull red heat or some of the aldehyde will be decomposed.

A much improved yield (about 80 per cent.) may be obtained by substituting pumice, coated with a mixture of silver and copper, for the roll of copper foil.


Perhaps this refers to precipitated metal.


Quote: Originally posted by SM2  
Just, you don't have to be an a-hole if you don't want to.

Oh, I want to. Maybe, though it will never be PC, it may be best if someone is, someone not having to represent the staff, in the best interests of a semi-serious science forum/information depository with 18989 threads and over a quarter million posts. This is nothing new for anyone who has accidentally read several of my posts. I'm a smartass by nature and others for sure are not good at it, and obviously a lifelong antisocial type.

There are threads that are much too long, see them. This is obviously a narrowly defined one, yet we want to start new branches of discussion in it like trioxane and preparation of acetaldehyde and paraformaldehyde (which belong in and already are in appropriate threads). If you support this, that's your problem, I want no part of it. Explanation seemed unnecessary.




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[*] posted on 18-1-2013 at 18:31


Quote: Originally posted by blazter  
speaking of conversion of methanol to methanal, is something i've researched a bit myself and am interested in too. probably the most useful but of information i found on the topic is in the pdf that i've attached. it shows experimental data on various catalyists for the conversions and reaction conditions. if one could construct an apparatus that passed methanol vapor + air over a catalyist one could have a LARGE amount of methanal if they wanted.


Iron (III) oxide is a cited catalyst. One way to prepare, perhaps by dissolving Fe in Oxalic acid. Separate out the FeC2O4 (avoid an excess of H2C2O4 as it would complex back into solution) and heat. The thermal decomposition of Iron oxalate produces a very fine form of FeO and Fe (actually burns in contact with air). Further heating can form Fe2O3 (see "Thermal decomposition of ferrous oxalate dihydrate studied by direct current electrical conductivity measurements" by K. S. Rane, A. K. Nikumbh and A. J. Mukhedkar, link http://link.springer.com/article/10.1007%2FBF01113573?LI=tru... ). Well, at least, this is a possible route to an Iron (III) oxide catalyst.
---------------------------------------------------------------------------------------

For Copper oxalate's thermal decomposition as a source of fine Cu, please see "The thermal decomposition of copper (II) oxalate revisited" by Emmanuel Lamprecht, Gareth M. Watkins and Michael E. Brown. Link: http://eprints.ru.ac.za/436/1/Lamprecht_The_thermal_decompos...


[Edited on 19-1-2013 by AJKOER]
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[*] posted on 19-1-2013 at 06:05


I must ask, why go through all the trouble of making oxalates? There are much simpler ways to obtain iron oxide, and copper oxide can be obtained by decomposing its carbonate. If it's to obtain a finely divided powder, it's not worth it, that's what the mortar and pestle is for. If all else fails, use two sheets of paper and a hammer.

I'll tell you what the real challenge with this synthesis is, to do it safely and controllably. Making the catalyst is no problem, even sodium carbonate can be used. What would be useful to know is how to mount the catalyst into a tube of some sort.




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[*] posted on 29-12-2013 at 18:48


Quote: Originally posted by S.C. Wack  
A stream of air is driven through the alcohol causing a mixture of air and alcohol vapour to pass through the copper coil, which should be heated until it just glows.


A little word of caution on this for anyone who tries it. The chemicals contained in this are flammable, and with the air bubbling, they are getting mixed with O2. So the tubing has a potential of air/fuel explosive. Having an open flame for heating can be the initiator. If its glass equipment you don't want to be near it should it go off. Take precautions.
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[*] posted on 30-12-2013 at 14:56


Quote: Originally posted by roXefeller  
If its glass equipment you don't want to be near it should it go off. Take precautions.


The combustion tubes of yesteryear were porcelain, 2-5 mm thick walls.




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[*] posted on 31-12-2013 at 15:52


I'd probably use a brass tube to do this, as its easy to heat and has more copper for the catalysis, but any other glassware in the setup is still a danger.
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[*] posted on 31-12-2013 at 17:55


Combustion tubes can be wrapped with very fine piano wire to reduce the explosion hazard. It was used in the stanley steam boilers. This doesn't eliminate the hazard.
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[*] posted on 10-2-2018 at 19:49


Hi, I'm very new here. Due to my condition and living arrangement I can only use that which is otc or inexpensive. So I'm curious: could the cleaning material known in America as "chore boy", a copper wire padding similar, at least in concept, to steel wool, be used as the catalyst? I would imagine that, like steel wool, this material would be coated in some form of protectant so would possibly need to be checked for, perhaps a paraffin. i can't recall a time when I ever saw any with an oxidized appearance. It's the closest thing I can imagine to as "copper gauze" and I don't have any silver wire, at least, not to my knowledge. I've personally reduced oxides on copper by dipping hot copper, not even red hot (at least that I could see) into methanol and it came back shiny as if new. This was a few old pennies I'm speaking of and nothing more. Ives learned so much since I've found this forum. Thank you for your wisdom and your time.
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[*] posted on 11-2-2018 at 07:34


The wise let me overhear them saying how you have been elected to determine the optimum packing and surface area of the Cu for yield. There is a touch of machine oil on Chore Boy, and 3M's item is something with a copper coating.



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[*] posted on 13-2-2018 at 16:35


Quote: Originally posted by Mailinmypocket  
Quote: Originally posted by SixTough  
I think it was Norris' book on organic chemistry that suggests plainly heating copper rod to very hot and submerging it into methanol. No yields were stated but the simplicity is so pleasing.

I will try it some day (probably not soon) just because it is so incredibly simple :o


I've done this many times, the methanol never ignited but I don't know how many times you need to dunk the copper into the alcohol to have any appreciable amount of anything form. It does make a faint formaldehyde smell though.


Wrong quot sorry

[Edited on 14-2-2018 by Photosensitive]
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[*] posted on 13-2-2018 at 16:38


Quote: Originally posted by S.C. Wack  
Typical procedure, from Hale in SM library: Methyl alcohol (100 ml) is placed in a flask which is kept at a temperature of 40°, and connected to a horizontal combustion tube in which a roll of copper foil (5 cm. long) is placed. The other end of the combustion tube is connected to a condenser and a well cooled receiver.

A stream of air is driven through the alcohol causing a mixture of air and alcohol vapour to pass through the copper coil, which should be heated until it just glows. The reaction will proceed without further heating and a solution of formaldehyde in methyl alcohol will collect in the receiver.

Small explosions on the copper do no harm; but the temperature should not exceed a dull red heat or some of the aldehyde will be decomposed.

A much improved yield (about 80 per cent.) may be obtained by substituting pumice, coated with a mixture of silver and copper, for the roll of copper foil.


Perhaps this refers to precipitated metal.


Quote: Originally posted by SM2  
Just, you don't have to be an a-hole if you don't want to.

Oh, I want to. Maybe, though it will never be PC, it may be best if someone is, someone not having to represent the staff, in the best interests of a semi-serious science forum/information depository with 18989 threads and over a quarter million posts. This is nothing new for anyone who has accidentally read several of my posts. I'm a smartass by nature and others for sure are not good at it, and obviously a lifelong antisocial type.

There are threads that are much too long, see them. This is obviously a narrowly defined one, yet we want to start new branches of discussion in it like trioxane and preparation of acetaldehyde and paraformaldehyde (which belong in and already are in appropriate threads). If you support this, that's your problem, I want no part of it. Explanation seemed unnecessary.


How can i make a 37% or 32% formaldehyde in water out of the methyl alcohol formaldeyhde solution which i get in the recieving flask Thanks!
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[*] posted on 2-3-2018 at 08:17


Hi everyone. I searched a little bit and I remember somebody saying they wanted to make formaldehyde, somebody else recommending pcc, and then the other person responding that they can't get that in their country. I apologize if this is the wrong forum, as I can't seem to find that exact conversation. Anyways, I found an otc source of pyridinium chlorchromate, though I don't know the concentration and I don't know the price, as I've never needed to put myself into a situation where I'd need to purchase such a product. Anyways, this pcc is found in a certain in vitro urine test adulterant likely sold at a "tobacco" shop near you. Most of these tests involve the use of oxidizers, one being nitrites, one being peroxide/per oxidase, and one that made me sit up, pyridinium chlorchromate. The name of the brand that has the pcc is "urine luck". I'd like to be able to tell you with absolute certainty the percentages, the likelihood of success with the use of this, and the price (which I suspect could be ridiculous. I've heard stories that put the price range for these things near 40 us$, and it's not a pure substance. Anyways, I hope this helps you on your journey toward whatever experiment you are interested in attempting. Just be safe, likely you already know, but formaldehyde is often labeled as carcinogen. Chromates aren't exactly nontoxic either (see Erin brockovich). Anyways, hope this helps.
Ps, btw, if you have a "GNC" store near you, or equivalent, perhaps you can find it there. I haven't subjected myself to their extortionist pricing in some time.

[Edited on 2-3-2018 by Omniquist]
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