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ddm
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Anybody here still interested in this electroreduction? Been playing with this for the last 3 yrs.
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Sydenhams chorea
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Quote: Originally posted by ddm  | | Anybody here still interested in this electroreduction? Been playing with this for the last 3 yrs. |
Is a bear catholic? Does the pope shit in the woods?
More seriously, electroreductions can be very versatile. Electrochemical reactions in a whole if the right conditions can be emulated correctly. I'm
thinking about the preparation of simple amines from nitroalkanes, reduction of oximes, but also electro-oxidations. Interesting subjects here are eg.
the preparation of 2,5-dimethoxytetrahydrofuran from malic acid oxidation in an undivided cell, benzaldehydes from propenylbenzenes, ... The
simplicity of the work-up makes all this so appealing imo.
Please share what you want if you will. I'm currently building a couple of simple cells that are more user-friendly than proposed by the starter of
this thread, generally using Tyvek as a diaphragm.
Maybe it could also be a good idea to pool interesting references concerning electrochemical syntheses?
Il n'y a point de sots si incommodes que ceux qui ont de l'esprit.
François de La Rochefoucauld.
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starman
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| Quote: Originally posted by ddm | | Anybody here still interested in this electroreduction? Been playing with this for the last 3 yrs. |
Absolutely.Please share.
@Sydenhams My experience with Tyvek wasn't positive(bad pun) too little current passing. Far better with the battery envelopes.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
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mineralman
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OTTO SNOW talks of forming a paper cylinder and useing gelatine in water to coat it with. I dont know if this works with hydrogenations.
Also, I havn't read any mention of "ANODE BAGS", These are used to stop unwanted insoluble impurities from the anode entering the plateing/reaction
solution,
MATERIAL like DYNEL,VINYON,NYLON & POLYPROPYLENE fabrics, COTTON TWILL & DOUBLE FLANNEL have all been used in the past.
If used in conjunction with the battery bags, could this be a usefull addition to the process? just a thaught MM
[Edited on 15-6-2012 by mineralman]
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mineralman
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two quickies.
Anyone have a pdf/file of OTTO's book on industrial manufacture I could download? Its the section on electro reduction that intrests me. particularly
the making of your own cell deviders from unsized paper and gellatine.
second is SLIGHTLY OFF TOPICISH SAFETY CONCERNED (?)
With Microwave-assisted CTH so simple, why use a route with poisonous Metalic Hg & its salts?
Hope this was ok to post, but I have no problems with removeing it. MM
[Edited on 30-6-2012 by mineralman]
Attachment: Microwave-Assisted_hydrogenation.pdf (856kB)
This file has been downloaded 2160 times
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Organicus
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| Quote: Originally posted by mineralman | two quickies.
Anyone have a pdf/file of OTTO's book on industrial manufacture I could download? Its the section on electro reduction that intrests me. particularly
the making of your own cell deviders from unsized paper and gellatine.
second is SLIGHTLY OFF TOPICISH SAFETY CONCERNED (?)
With Microwave-assisted CTH so simple, why use a route with poisonous Metalic Hg & its salts?
Hope this was ok to post, but I have no problems with removeing it. MM
[Edited on 30-6-2012 by mineralman] |
Text from Otto Snow's Book as requested:
| Quote: | | "An inexpensive substitute for these cups may be made as follows: Wet a sheet of paper, wrap it several times about a large test-tube, folding in to
close the bottom. Mold the paper into shape, then coat it, inside and out, with a hot solution made by dissolving 75 grams of gelatin and 100 g.
K4Fe(CN)6 in one liter of water. When the cup has drained and cooled, it may be removed, and inverted until dry." From: Exercises in General Chemistry
(1924) |
But instead of building a divider out of paper, open up a car battery. There are a lot of separator bags which suite perfect as membranes. Clay or
Paper dividers will produce a lot of resistance and more resistance means more heat in your cell to come by.
best regards
[Edited on 30-6-2012 by Organicus]
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mineralman
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Thanx Organicus, thats great info. Was there any info on paper type? ie: un sized, newspaper etc
I just thaught it would be fun to play with some day soon ( unless the police invent a way to make something out of nothing), Hmm, better make that
sometime in the future
ON THE SUBJECT OF THOSE SCEALED BATTERYS, i HAVE ONE (Oops), a buggered one that is.
It has a bulge to the posative side, I guess it's a defective bat, as theres no damage evident in/around the area.
I took the center strip off the top via a well plased screwdriver and revealed a series of nut's?, all bar two of them had a dip in the center & 2
that had a slight bulge to them were on the negative end, is this normal?
I wanted some input b4 dismanteling the battery, just to be on the safe side, im assuming these can be un done to empty the acid, but am worried that
there could be pressure build up and tampering with them may cause a spray of the acid, possible or not an issue?
any helpfull advice would be much apreciated. thanx MM
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HollowMan
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Hi,
I have a view questions about the battery bag method:
- is there any possibility to stick/ weld the bags?
Because of it´s small shape the cooler (anode) cannot get deep into the bag or in the analyte solution. Thats why I want to make an other shape to
increase contact.
- are there any shops which sell the bags on its own?
[Edited on 22-3-2017 by HollowMan]
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Melgar
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| Quote: Originally posted by HollowMan | Hi,
I have a view questions about the battery bag method:
- is there any possibility to stick/ weld the bags?
Because of it´s small shape the cooler (anode) cannot get deep into the bag or in the analyte solution. Thats why I want to make an other shape to
increase contact.
- are there any shops which sell the bags on its own?
[Edited on 22-3-2017 by HollowMan] |
The material you want is called "microporous polyethylene film", and lots of things are made from it. However, often those materials are hydrophobic,
and water won't be able to absorb into it in order to conduct.
Actually, I just found this paper, going to post it somewhere else too, because it seems really useful:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/197900...
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Corrosive Joeseph
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I read somewhere Tyvek material works as well the aforementioned battery bags..............
Or have a unglazed porcelain pot made.............. Wall thickness should be as thin as possible.............
/CJ
Being well adjusted to a sick society is no measure of one's mental health
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HollowMan
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| Quote: Originally posted by Melgar | | Quote: Originally posted by HollowMan | Hi,
I have a view questions about the battery bag method:
- is there any possibility to stick/ weld the bags?
Because of it´s small shape the cooler (anode) cannot get deep into the bag or in the analyte solution. Thats why I want to make an other shape to
increase contact.
- are there any shops which sell the bags on its own?
[Edited on 22-3-2017 by HollowMan] |
The material you want is called "microporous polyethylene film", and lots of things are made from it. However, often those materials are hydrophobic,
and water won't be able to absorb into it in order to conduct.
Actually, I just found this paper, going to post it somewhere else too, because it seems really useful:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/197900... |
I have the bags already from a car battery. The problem is, that the welding und every site is broken already and I try to use an other shape.
Sticking PE and finding a resistant glue is really not easy.
Could you tell me about some common stuff which is made out of this microporous material?
The problem with the porous porcelain is, that the resistance in comparison to membrane is really. And as I sad, my idea was to bring both electrodes
as close as possible to each other for highest conductivity. This is also easier to mange with just a membrane wrapped over the cooler.
Anyone tried the lamb condom method? Usually its a great cell divider, but I don´t know how it works in acidic conditions..
In a previous post was someone telling, that he will try a goretex membrane (microporous ptfe). I don´t know if this is microporous enough because it
just prevents for water drops. water vapor will come through and its just working within the right steam pressure gradient. What do you think?
Thanks for the .pdf but I would prefer to solve this problem with already available and tested material at first
[Edited on 25-3-2017 by HollowMan]
[Edited on 25-3-2017 by HollowMan]
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HollowMan
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| Quote: Originally posted by Corrosive Joeseph | I read somewhere Tyvek material works as well the aforementioned battery bags..............
Or have a unglazed porcelain pot made.............. Wall thickness should be as thin as possible.............
/CJ
|
I´m still not sure about the minimum pore size which is required to prevent the electrolytes from mixing.
I just filled some water in a battery pag (PE mixture) and after about one hour first drops appeared on the surface of the membrane. The pore size is
about 50 - 100 Angstrom.
The pore size of gore tex is between 0,02-6 micrometer.
I guess the pores of the porcellan are definitly smaller than the battery bags.
Anyone tried stretched PE folies, which are used in the kitchen?
I don´t know where to get porous porcellan with min wall thickness. I´ve tried usuall flower pot with about 0.5 cm diameter, but the resistence is
really high. That means a lot of heat and max 8 A current flow (possible should be about 25 A with my current source). This results in low reaction
rates.
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Melgar
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| Quote: Originally posted by HollowMan | | I have the bags already from a car battery. The problem is, that the welding und every site is broken already and I try to use an other shape.
Sticking PE and finding a resistant glue is really not easy. |
In that case, you need to combine, say, silicone glue with a needle and thread. Or staples, if you think you can coat them all with glue. I have some
teflon thread I could sell you cheap, but really, polyester would probably work fine, and that's what most thread is made out of.
| Quote: | | Could you tell me about some common stuff which is made out of this microporous material? |
Motorcycle covers, and those protective disposable suits like they wear in microchip clean rooms. I think the lead-acid battery membranes are
multiple layers though, that have been modified to change their interaction with water.
| Quote: | The problem with the porous porcelain is, that the resistance in comparison to membrane is really. And as I sad, my idea was to bring both electrodes
as close as possible to each other for highest conductivity. This is also easier to mange with just a membrane wrapped over the cooler.
Anyone tried the lamb condom method? Usually its a great cell divider, but I don´t know how it works in acidic conditions..
In a previous post was someone telling, that he will try a goretex membrane (microporous ptfe). I don´t know if this is microporous enough because it
just prevents for water drops. water vapor will come through and its just working within the right steam pressure gradient. What do you think?
Thanks for the .pdf but I would prefer to solve this problem with already available and tested material at first |
Polyvinyl alcohol is really easy to get. I thought it was in disposable diapers, but actually that's a sodium salt of polyacrylate, Polyvinyl alcohol
is used to make plastic that will dissolve in water though, like those dishwasher tabs. It's also used for 3D printing, because you can use it to
make a support structure that can be dissolved off with water. With PVA, you could dissolve it in water, spray it on a form, and let it dry a little
bit, then spray on the crosslinking agent, in a low-concentration solution. It would turn softer and more gelatinous when it got wet, but after
crosslinking, it'd keep its form, and it should also be a lot more conductive than any of the alternatives proposed so far. The only downside seems
to be that durability and conductivity are inversely proportional, but for this type of thing, durability isn't really a top priority. You'd just
need to be careful with it.
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Corrosive Joeseph
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| Quote: Originally posted by HollowMan | | Quote: Originally posted by Corrosive Joeseph | I read somewhere Tyvek material works as well the aforementioned battery bags..............
Or have a unglazed porcelain pot made.............. Wall thickness should be as thin as possible.............
/CJ
|
I´m still not sure about the minimum pore size which is required to prevent the electrolytes from mixing.
I just filled some water in a battery pag (PE mixture) and after about one hour first drops appeared on the surface of the membrane. The pore size is
about 50 - 100 Angstrom.
The pore size of gore tex is between 0,02-6 micrometer.
I guess the pores of the porcellan are definitly smaller than the battery bags.
Anyone tried stretched PE folies, which are used in the kitchen?
I don´t know where to get porous porcellan with min wall thickness. I´ve tried usuall flower pot with about 0.5 cm diameter, but the resistence is
really high. That means a lot of heat and max 8 A current flow (possible should be about 25 A with my current source). This results in low reaction
rates. |
I'm no expert but the I was always under the impression that the electrons must cross the barrier but the atoms/molecules/compounds
can't.............
That would suggest to me that 'pore size' should be sub-atomic and actually nothing to do with it at all..............
Flower pot must hold electrolyte whilst passing charge through it's walls.............
That's it..................!!
Being well adjusted to a sick society is no measure of one's mental health
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Melgar
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| Quote: Originally posted by Corrosive Joeseph | | I'm no expert but the I was always under the impression that the electrons must cross the barrier but the atoms/molecules/compounds
can't............. |
Not quite, that's what the wire and electrodes are for: they conduct electrons through the wire, but obviously don't allow anything else to flow..
Now, an electrolytic cell is basically just a battery in reverse, turning electrical energy into chemical energy. But the charge that's transferred
in via the electrodes has to be balanced by another charge transfer, of ions. So the membrane has to allow ions to migrate across it, but it should
impede the flow of neutral fluids. Typically this is done by making the membrane out of something that looks like a huge maze of pores on the micro
scale. Neutral molecules won't get very far, or will go in circles, or go in and come back out, because there is just too much maze to get through by
random chance. Ions, on the other hand, have a charge, and thus are pulled consistently in one direction, and eventually find their way over.
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HollowMan
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| Quote: Originally posted by Melgar | | Quote: Originally posted by HollowMan | | I have the bags already from a car battery. The problem is, that the welding und every site is broken already and I try to use an other shape.
Sticking PE and finding a resistant glue is really not easy. |
In that case, you need to combine, say, silicone glue with a needle and thread. Or staples, if you think you can coat them all with glue. I have some
teflon thread I could sell you cheap, but really, polyester would probably work fine, and that's what most thread is made out of.
| Quote: | | Could you tell me about some common stuff which is made out of this microporous material? |
Motorcycle covers, and those protective disposable suits like they wear in microchip clean rooms. I think the lead-acid battery membranes are
multiple layers though, that have been modified to change their interaction with water.
| Quote: | The problem with the porous porcelain is, that the resistance in comparison to membrane is really. And as I sad, my idea was to bring both electrodes
as close as possible to each other for highest conductivity. This is also easier to mange with just a membrane wrapped over the cooler.
Anyone tried the lamb condom method? Usually its a great cell divider, but I don´t know how it works in acidic conditions..
In a previous post was someone telling, that he will try a goretex membrane (microporous ptfe). I don´t know if this is microporous enough because it
just prevents for water drops. water vapor will come through and its just working within the right steam pressure gradient. What do you think?
Thanks for the .pdf but I would prefer to solve this problem with already available and tested material at first |
Polyvinyl alcohol is really easy to get. I thought it was in disposable diapers, but actually that's a sodium salt of polyacrylate, Polyvinyl alcohol
is used to make plastic that will dissolve in water though, like those dishwasher tabs. It's also used for 3D printing, because you can use it to
make a support structure that can be dissolved off with water. With PVA, you could dissolve it in water, spray it on a form, and let it dry a little
bit, then spray on the crosslinking agent, in a low-concentration solution. It would turn softer and more gelatinous when it got wet, but after
crosslinking, it'd keep its form, and it should also be a lot more conductive than any of the alternatives proposed so far. The only downside seems
to be that durability and conductivity are inversely proportional, but for this type of thing, durability isn't really a top priority. You'd just
need to be careful with it. |
Thanks so far for you help.
I already had time to mess around with this car battery bags. They are going to make me crazy. It can be glued after the use of a primer. But every
primer is specific for the glue. So the next problem comes with it: The glue has to seal up the bags and must be resistent
against:reductiv/oxidative/acidic conditions, not soluble in ethyl acetate, ethanol, acetic acid, water.
I´m no specialist for glues and for every test you have to buy the primer.. In two cases after about 2-4 hours just right before the end the glue
dissolved or did´nt seal up enough.
After that glory experience I went on with the well known lamb skin condom which is recommended by uncle fester in his books.
For this reaction I used hcl instead of sulfuric acid in the catholyte solution (to make it as close enough as slotte..). As I already feared the next
problem was just right before:
cl- could pass the condom and was greatly oxidized to cl2, which comes out in a big amount directly into my room. Thats something most of you don´t
like to inhale the next hours I promise. But also the condom wasn´t amused from the cl2 (or the other conditions) because after about 45 min it felt
apart like a wet pice of toilet paper :/.
Anyone tried goretex membrane sucessfully? There is a thread about the usage of goretex as a cell divider (http://www.sciencemadness.org/talk/viewthread.php?tid=30448#...). But I´m not sure If the permeability is much different when the surface tension
of water is being lowed by addition of ethanol/ethyl acetate...
After all experienced with this reaction I´m really going to be a bit pissed. It´s not possible that it´s so hard to find a fucking suitable
membrane.
One more additional info to the car battery bags:
I tested their permeability of water be filling them up with it and let it stand for about 20 hours. After that from about 200ml ablout 30 came thru.
Of course that are other conditions than being surround from water. Something else I recognized was, that during the reduction (15 A) the anode
electrolyte started to increase more and more. Usually the osmotic flow should go from the analyte to the catholyte solution... (happened before the
glue dissolved). Anyone know what happened? The membrane was in direct contact to the cathode. I don´t know of this had an influence.
Additional info to the lamb condom:
The permeability of water did not exist, thats why I was positive surprised at first. For me it looks like just ionic transfer is possible thru this
membrane. Before the condom got wasted the electrolyses had a really hard resistant just like the flower pot. That means not more than 8-9 A are
possible by nearly minimum distance between anode/cathode. In case of the battery bags more than 25 A worked without a problem.
Some helpful comments are highly appreciated
Thanks
PS: The needle/thread method I didn´t tested so far. Silicone on its own doesn´t fit on the bags. It´s like putting some hot glue on a teflon pan.
[Edited on 27-3-2017 by HollowMan]
[Edited on 27-3-2017 by HollowMan]
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yobbo II
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Going back to the flower pot.
If you obtain a ceramic tile and and an 'angle grinder', also called a disk cutter or a friction cutter and make sure you have a disk for cutting
stone in it.
The glaze can be removed from the tile and you can also make the tile much thinner by carefully rubbing at the surface. Put the tile down an a soft
firm surface that will hold it it place. Some time is required to get the tile really thin.
The resistance if this very thin ceramic will be less than the much ticker walled flower pot. Use a ceramic tile that you think has more porosity than
one which have been fired at a high temperature.
It should be possible to make you own ceramic membrane by biscuit firing a suitable mix?
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HollowMan
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I´m not sure how much the resistance deepens on the wall thickness. The condom was so thin but the resistant was definitely as high as the much
thicker clay cylinder. Of course I don´t know the difference in the pore size..
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Melgar
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| Quote: Originally posted by HollowMan | | PS: The needle/thread method I didn´t tested so far. Silicone on its own doesn´t fit on the bags. It´s like putting some hot glue on a teflon pan.
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What kind of silicone glue did you try using? The best one I've found is the GE stuff that comes in a tube that looks like this:
That will stick to everything, even teflon. It doesn't stick very well to polyethylene, but the point is just to make a gasket that the needle and
thread would hold the polyethylene to. When I had to make a seal between two polyethylene parts, I bolted them together, then loosened the bolts and
put this glue between them, then tightened them down again. You could do this with a needle and thread too, but you should probably fold it over
itself first before doing that, so you get a better seal.
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S.C. Wack
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An unglazed crucible. Another option: sintering glass powder of the right mesh size.
Gentle hydrogenation with Pd in GAA + H2SO4 or some forms of Pt might be just as effective?
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HollowMan
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Alright I´ll tell you how I´ll go on:
First I try the easiest version: Getting a pice of Goretex membrane and look if this works.
After I´ll get the glue with needle/thread to try this variant
Anyway I´m still open for more advices ideally proven ones
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HollowMan
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| Quote: Originally posted by S.C. Wack |
An unglazed crucible. Another option: sintering glass powder of the right mesh size.
Gentle hydrogenation with Pd in GAA + H2SO4 or some forms of Pt might be just as effective? |
An unglazed crucible is too small for my cooler and I prefer something flexible. Did you try it? I´m afraid of the resistance, too.
I don´t have the possibility to sinter my own membrane. Also as cheap as possible is recommended so Pt/Pd variants are to expensive for me. You see
I´m still at the beginning I don´t even know how the yield will be with this reduction method.
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yobbo II
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Are RO filter membranes any addition?
https://www.espwaterproducts.com/ro-filters-membranes/
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Melgar
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I'm pretty sure they do the opposite of what you want: allow neutral molecules through while excluding ions.
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HollowMan
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After playing for a while with this kind of reduction Tyvex seems to be the best variant as cell divider.
But still a few problems occured:
- temperature controll (what is the best temperature for this kind of reduction?? usually I can hold it at about 24°C
- how can the rxn determinated? Just by watching increasing H2 Evolution? thats not that easy, because after every step in the reduction
alken->alkan->oxim->hydroxylamine the h2 evolution increases.
- the best result I got was 50% with a substituted nitroalkene. Usually 60% or more should be possible
- what kind of catalytsolution is the prefered one?
- 4:4:1 (EtOH:GAA:50%H2SO4)
- 2:1:1 (EtOH:GAA: 6M H2SO4)
- Substitute EtOH with IPA?
Does a higher acid concentration lead to more Polymerisation via intermolecular diels alder reaction?
The reaction time was calculated as followes:
[m (g)* z (=8 Faraday)*F (96485 A*s/mol)] /[I (Ampere (A))*M (molweight (g/mol)]
Usually I determinated the rxn after about 1,25x of the calculated reaction time
Anyone knows a good solvent for the TLC?
The nitropropene is good visible with PE:EA (petrolether:ethylacetate) 3:1 but the Amine wasn´t running...
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