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CycloKnight Harmless
Posts: 45
Registered: 4-8-2003 Location: United States of Britainnia
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posted on 26-1-2005 at 04:56
Benzaldehyde via Cl2/toluene
Hi folks,
what follows is some discouragement for the Cl2/toluene method and then a procedure for making benzaldehyde using electricity.
I would just like to add that anyone attempting to make benzaldehyde using the toluene chlorination route to think again, unless you know EXACTLY what you are doing. It is a bitch and a half. I've done it, twice. It will take months to get rid of the benzyl chloride smell off the glassware & general lab area.
First time I did this experiment, my method for checking the progress of the chlorination was to intermittently weigh it out (and measure the volume), to measure the density. It works, but the stuff is tear gas'n a half. Within seconds of opening the reaction vessel, my eyes were involuntarily fused shut, with tears running down my face...Ahh the joys of chemistry. I would say working with benzyl chloride is about 5 times worse than working with chlorine, at least.
By the end of the first experiment, I'd been chlorinating for days and I had fairly pure benzyl chloride (at least 70%, pre distillation) which is only half way there - "To hell with this!" I thought. I dumped my benzyl chloride, only to learn a month later that I could have reacted it with my Kg of hexamine to make benzaldehyde!!!!! (Instead of the benzal chloride route I was aiming for.)
During the second experiment, I used a hydrometer actually inside the 3L 3neck RBF to measure the density without actually having to open the RBF. This is a genuinely good idea. It was held in place by allowing the top couple inches of the hydrometer to fit inside a large tube that was fixed to the cork of the middle neck. The idea is that as the hydrometer bobs around (up and down) inside the refluxing flask it can't go anywhere but up and down (so it can't smash against the side of the flask during reflux).
But, in the end I got fed up and decided to go electrochemical instead.
At first the chlorination thing seemed quite tempting, but halfway through I thought the electrochemical route (which I'd done before) was like a dream come true! And it is by comparison, unless you live in a desert like Mendeleev said.
A good way of doing this reaction is by using US patent 808095. Its the electrochemical route, but runs 24 hours a day, and with my 2amp DC power supply, takes around 60 hours to fully regenerate. It produces around 100ml benzaldehyde per run (based on 1Kg of regenerable oxidizer).
I've done this many times, and it works like a charm. Basically, I do it in a giant 3L pyrex beaker, with 2 lead electrodes (the positive anode is larger with a much larger surface area than the cathode). This requires no membrane!
It is absolutely fool proof! If anyone wants to see pictures, I will take them and post them here - just say.
I use approximately 1Kg of manganese ammonium alum, made by adding manganese sulfate to sulfuric acid (60%+) which already has an excess of ammonium sulfate dissolved in it. The molar ratio for MAA is 2 moles manganese sulfate to 1 mole ammonium sulfate. It is a orangy-yellow precipitate. When you pass a current through it - it oxidizes and turns dark red. Its really cool to watch, you see the dark red pouring off the anode, gradully turning the yellow mix dark red. It lasts a long time, I've never worn it out - getting used over and over and over again!
The ratios (from the patent, scale down accordingly) are: 47.5 Kg mangano-ammonium sulfate, 45 Kg water, 79Kg of 98% sulfuric acid.
The reaction mix is heated to 50 C, and with stirring 4Kg toluene are added. When the dark red solution has turned yellow again - reaction is finished!!! The solution REAKS of cherries!
The patent says steam distil, but don't. Use solvent extraction, the steam will leach out your acid from the mixture. The product (from 4kg toluene) is 3.7Kg benzaldehyde, 0.6 Kg toluene, of course if you are using 1Kg of oxidant instead of 47.5 then you will get about 100ml or so.
that yet), etc. It can also be used for producing organic acids by adjust the reaction temperature and acid concentration. The only things this cell consumes is reactant (ie. toluene, methyl alcohol, ethyl alcohol, etc) and electricity...My point exactly.
I see that people are looking for non-electrochemical methods for making benzaldehyde, but I suggest taking a closer look at this procedure, I've used it many, many times and it is quite versatile. It is the real mckoy.
I made my manganese sulfate from dismantled D size alkaline batteries, by reacting the MnO2 (100g per battery) with HCl to make the chloride (vent chlorine outside!), and then reacting the chloride with sulfuric acid to make the sulfate.
BTW, I then used most of that sulfate to make the carbonate (by reacting it with sodium bicarbonate) and then with acetic acid to form the acetate, but that is for another experiment that I won't go into detail here....Maybe down at the hive when it's up and running again. Hey hive guys, I'm wondering if this oxidizer (MAA) can be used to react benzene+acetone in the same way manganese(III)acetate can. That is my next project.
Anyway, the sulfate isn't hard to make from scratch, and ammonium sulfate from the garden centre was first purified by doing the following:
The crude brown ammounium sulfate was dissolved in water (almost saturated), then vacuum filtered (any filter will do, really) a couple of times to remove most of the gunk. Then I boiled it down to a mushy mix with constant stirring, then let it cool a bit. Then I added methylated spirits (or denatured alcohol if you are in the US) and all that brown crap just floats to the top, carefully remove it with a baster/syringe/dropper. I used a dropper, which took a while!
When your crystals are reasonably white, just boil off all the alcohol, done!! You can use your purified ammonium sulfate (as is)for the electrochemical cell. That wasn't hard, was it?
I made my electrodes by making a form out of Al foil, and then melting lead in a crucible made from a STEEL deodorant can cut in half, with a handle made from a C-clamp stuck on the top. I used a blow lamp to melt the lead (I put the lead fishing weights in the can and heated), then just poured the lead into the Al foil mold on a disused wooden breadboard, mmm - I love the smell of burnt wood. Or you could just buy lead sheet, but I couldn't be bothered.
[Edited on 2-13-2005 by Polverone] Organikum clandustrial priest Posts: 1984 Registered: 12-10-2002 Location: Europe Member Is Offline Mood: Missing the old SCM....
posted on 26-1-2005 at 05:27
The electrolytic method described is the one presented by Uncle Fester, patent US808095. It has the same drawback like many electrolytic pathways and like the ammonium-persulfate method:
The amounts of oxidant etc. used are a little large - scaling up to interesting amounts of benzaldehyde - 500ml or more - calls for quite bulky setups, lots of H2SO4 etc. Ok when you have a spare garage to dedicate for benzaldehyde production though.
You can do the math yourself to find this out.
When going technical/continous, the toluene oxidation by air in the gasphase as posted by Polverone are probably much better, when doing batches - we will see.
I agree that BzCl is a bitch. Therefor I by now experiment to find and later to present a WORKING OTC kitchen method with MnO2 (pigment quality - pyrolusite) in the 100ml product range. /ORG
Attachment: us808095_bdehyde_alectro1908UF.djvu (66kB) This file has been downloaded 1002 times
The USA are not the center of the world.
CycloKnight Harmless
Posts: 45
Registered: 4-8-2003 Location: United States of Britainnia
Member Is Offline Mood: Experimental
posted on 26-1-2005 at 06:39
Electric benzaldehyde
Yes, i agree that there is a vast excess of oxidant. Though, it is perfectly regenerable and not too much of a bother - but scaling up is a problem...for single batch runs. My cell holds exactly 2.2 litres of acid-oxidant mix, I don't think it's alot of work for 100ml - though that does depend on what you want it for. It's really just a case of switch on, and let stir on the stirrer plate. A couple days later react and extract. Practically a one pot synth, and able to produce all kinds of compounds. If you need such a unit to produce formaldehyde, why not use it to make benzaldehyde as well? Or benzoic acid? I did a little bit of critical path management, and I ended up with the above method as the path of least resistance (For me, at least).
Also, should you get busted - your lawyer could always argue that you use the cell for making formaldehyde...Or whatever, there is a long list to choose from.
I am thinking of working on some kind of 2 phase oxidizing mixture, whereby the cell (stirred) is continuously run with a very large excess of toluene floating on top which is continously removed and extracted (distilled).
Excess toluene simply being returned to the cell. The benefit of this is that the cell runs constantly, but only needs a relatively TINY amount of acid-oxidant mix (tiny compared to industrial sized single batches). Intead of having the large excess of oxidant that sits in the bottom of the beaker, only enough that dissolves is necessary here, since it's continuously regenerated!
Larger current means more mix (or larger + electrode) - but you see my point. Also, the lead electrodes do not corrode. At least not to an obvious extent - they change from shiny to grey. Over time alot of benzaldehyde could be made and the process could be made mostly maintenance-free. Occasionally acid and oxidant carryover will need to be removed from the benzaldehyde extractor/distiller, but that's not much maintentenance. This process (if workable) is mainly limited by the anode surface area and the amount of current you are able to supply! (and corresponding cooling of course...)
However, after a trial run it may be found that the oxidant needs to be toluene-free when it is regenerated by the anode, which would mean a separate vessel (with heating and cooling inbetween to drive off toluene prior to regneration) for regenerating. I suspect that benzoic acid by-product could be generated if toluene is present in the mix while current is passed - but I don't know yet.
Maybe someone else knows?
Polverone Super Administrator
Posts: 2300 Registered: 19-5-2002 Location: The Sunny Pacific Northwest Member Is Offline Mood: walking on sunshine posted on 26-1-2005 at 13:41 Pictures!
Yes, let's see some pictures. I always enjoy gazing upon others' DIY setups. Upload to the "scipics" account as described here so that you can place multiple, inline images in your post instead of using attachments.
PGP Key and corresponding e-mail
Tetramer Harmless Posts: 2 Registered: 25-1-2005 Member Is Offline posted on 26-1-2005 at 15:58 Quote:
Originally posted by Icarus
There is another oxidant worth trying: persulphates are used in electronics etching and easy available. I read a patent that used persulphates and compounds of copper, silver, or iron as catalysts for the toluene->benzaldehyde. I tried without succes before using ammonium persulphate like patent.
Reaction worked some. I smell benzaldehyde. I was unable to isolate it but I think I make mistakes. Persulphate is oxidant and other metals are catalyst. I use ammonium persulphate since I had not sodium persulphate. Maybe this is part of my trouble. I want to try again but cannot find lost patent
I wasn\'t born a threat, but I was born to be one.
Organikum clandustrial priest Posts: 1984 Registered: 12-10-2002 Location: Europe Member Is Offline Mood: Missing the old SCM....
posted on 26-1-2005 at 23:13
Posted by Osmium at the-hive: Quote:
Benzaldehyde
Ferrous-Copper Catalyst: Toluene (7.6 g.), water (35 ml.), ferrous sulphate (0.110 g.) heptahydrate, cupric acetate (0.072 g.) and methanol (8 ml.) are placed in a 250 ml. reactor.
Sodium persulphate (47.05 g.) in an aqueous-methanol solution of sodium persulphate is added slowly to the mixture which is maintained at 70.degree. C., in an atmosphere of nitrogen and under agitation.
The organic phase is separated after two hours and the aqueous phase is extracted with ethyl ether.
The combined organic phases are distilled to afford 8.29 g. (95% yield) of very pure benzaldehyde (compared against a pure sample).
US-Pat 4,146,582
/ORG
PS: Ammonium-persulfate should work too. Pleasse notive the big amount of persulfate needed. Smell of bitter almonds doesnt say much - it smells already in strong in traces in special when warm and with water.
[Edited on 27-1-2005 by Organikum]
The USA are not the center of the world.
S.C. Wack bibliomaster Posts: 973 Registered: 7-5-2004 Location: Cornworld, Central USA Member Is Offline Mood: Enhanced posted on 27-1-2005 at 01:01 misc.
NiO2: Eng. Pat. 22887, 1900
MnO2, H2SO4, and catalyst: GB138999
Belongs in the chlorination thread, if anywhere: GB816253 H2O2 and catalyst: US3531519
benzyl bromide and sodium nitrate: US1272522
CycloKnight Harmless
Posts: 45
Registered: 4-8-2003 Location: United States of Britainnia Member Is Offline Mood: Experimental posted on 27-1-2005 at 13:48 {img}http://www.sciencemadness.org/scipics/anode.jpg{/img} [Edited on 29-1-2005 by CycloKnight]
Icarus Harmless Posts: 12 Registered: 17-12-2004 Location: The Stratosphere Member Is Offline Mood: getting warmer
posted on 27-1-2005 at 19:56
"PS: Ammonium-persulfate should work too. Pleasse notive the big amount of persulfate needed. Smell of bitter almonds doesnt say much - it smells already in strong in traces in special when warm and with water. "
Someone who has forgoten more about chemistry, than I know about it, once said that there may be issues with the Cu salt and NH 3 complexing. Only one way to find out I suppose.
[Edited on 28-1-2005 by Icarus] [Edited on 28-1-2005 by Icarus] CycloKnight Harmless Posts: 45 Registered: 4-8-2003 Location: United States of Britainnia
Member Is Offline Mood: Experimental
posted on 29-1-2005 at 14:58
Manganese ammonium alum cell
Okay, as promised here is my photo essay of the mananese-ammonium alum cell, which can be used for the oxidation of various compounds. Here is the anode:
Here is the power supply:
The white powder in the coffee jar is the ammonium sulphate I made from the brown garden stuff using the simple purification procedure I described 2 posts ago in this thread. Here is the cell a few hours after the reaction has commenced:
It took about 3 days to convert all of the yellow mangano-ammonium sulphate into the dark red manganese ammonium alum.
Reaction takes place with vigorous stirring (50 degrees C), the 2 phases MUST be mixed for reaction to occur, I used magnetic and manual stirring to whip up the mixture. I let the reaction proceed for 1 day before finishing it up by heating to over 60 C and applying vigorous manual stirring with a nickel lab spatula.
The orange tinge to the toluene is indicative of the reaction progress. Not sure what the tinge is, condensation products of some kind I suppose? Reaction is now complete:
Extraction almost finished!! :
[img]http://www.sciencemadness.org/scipics/last blob.jpg[/img]
Total organics extracted (including a few hundred ml toluene used for extracting):
Product:
Cell is ready for re-use:
It is important to get as much of the organic material out of the cell as possible, otherwise it will get oxidized to the acid. This cell smells a bit like formic acid, due to benzoic acid being gererated when the current is switched on. It may be wise to do the final extraction with something like ether, so it will boil off easily after wards. Not so with toluene, enough always remains to interfere with the regeneration process for a while.
Let us have some more!
Sir yes sir, regenerating right away sir!
Current of 2 amps (at 5 volts) is flowing through the mix.
The black floating bits have nothing to do with this process. They are bits of carbon (dehydrated organics), the result of another experiment that I carried out immediately after the toluene oxidation run. Please ignore them.
CycloKnight Harmless
Posts: 45
Registered: 4-8-2003 Location: United States of Britainnia
Member Is Offline Mood: Experimental
posted on 29-1-2005 at 15:30
Yield
Okay, I would just like to say that the yield was a little on the low side, however please take the following into account: 1) Toluene wasn't toluene, it was a mixture of toluene, hexane and water.
2) The product was not washed prior to distillation, so I ended up with quite alot of black polymerised gunk (which appeared out of nowhere) in my flask.
In fact, I ended up with more gunk than product, oops. I thought that by using a vacuum this time I could avoid the high temperatures which would cause the product to degrade - I was mistaken. The toluene I used for the extractions was wet and had a boiling pt of around 86 C. Since the cell is mostly sulfuric acid it dried it (which I thought was a bonus!), so I didn't want to wash it - I wanted to recover dry toluene for other purposes.
See what happens when one takes shortcuts? So, most of my product was ruined, oh well - I'll just have to wait another 3 days... I should also say that toluene is a bit hard for me to get. I've been using this OTC solvent formulation called "Evo-Stik Cleaner 191".
Evo-Stik is a contact adhesive used in the UK, but the cleaning formulation is a mixture of solvents (and water too!). The solvents are toluene, hexane and small amounts of other solvents. For the reaction carried out in the photo essay above, I used 250ml of Evo-Stik solvent. Then I used a further 150ml or so for the extractions - though I could have extracted a bit more!
I did the extractions by adding the "toluene" to the 3L beaker, mixing it up real good and then just removing the top layer with a dropper. Doing it that way removes the need to pour the whole mix into a separating funnel and shake. An unnecessary risk (in my opinion).
I would say that as long as everything has been done correctly, the yield is much higher than what I managed, though I can't give a figure because of the lack of control conditions. My last cell contained an unknown quantity of oxidizer, and this is the first run with my new cell! So, this is the first run I've carried out in about 2 years.
I can say that practically no benzoic acid is produced is the temperature if kept at 50 C and no higher. The benzaldedhyde odour begins from about 30 sec after the toluene is added to the oxidizer mix.
The reaction takes several hours to complete. The heater on my hotplate isn't functional right now due to a damaged thermocouple probe, so I had to keep putting it on the stove ever few hours to heat it up a bit. My other hotplate has a weak stirrer and can't properly stir the mix...
In a couple days or so, the cell should be regenerated and I will try again and post the results here.
[Edited on 30-1-2005 by CycloKnight]
CycloKnight Harmless
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posted on 1-2-2005 at 01:29
Okay, I did another run last night and it was a success. However, it was only a partial run.
I estimated that the cell was no more than 25% regenerated and I managed to get 25ml of benzaldehyde from the mixture. The cell was only medium pink, as opposed to dark dark red when it is fully regenerated. The partial regeneration is due to organic acids which have been generated when the mixture is heated over 60 C.
I washed the toluene extracts twice, and there was negligible degradation of the benzaldehyde during distillation, and no scent of benzoic acid.
I started the distillation under normal pressure, as soon as the toluene was mostly gone (I let it run to 115 C) I then cranked up the vacuum and boiled off the remaining benzaldehyde until orange distillate just started to distill over.
There is a small problem I'm trying to work a solution for. Steam distillation is the way around it, but I want to avoid it at all costs.
The problem is that as the cell regenerates, some of the dark red oxidizer forms clumps on the anode, these clumps break off and settle to the bottom.
Mood: Experimental During the reaction these clumps of oxidizer don't react (unless they have first been pulverized) since they aren't dissolved.
After the toluene has been reacted and the reaction is finished, I have been heating up the mixture to drive off the excess toluene before regenerating. What has been happening is that the "clumps" have then been reacting at the higher temperature with residual toluene to form benzoic acid which stays in the cell.
I used to use steam distillation, which would just steam distill out all of the garbage, but it also leached out the cell acid - so I am keen to avoid it this time.
The benzoic acid interferes with the regeneration process by acting as a competing current carrier; some of the current produces dark red salt, and some of the current produces oxygen due to the benzoic acid. Obviously killing the cell efficiency and lengthening the regeneration time considerably.
This evening, I plan to try an ether extraction of the mix, and failing that - I will dump the whole mix into my 3L RBF and steam distill it. I've never tried ether before, I think it is worth a try. Steam distilling really does drive out all the oils and junk which can accumulate in the cell after a while, but it is not convenient for everyone.
One solution would be to use a glass rod with a flat end to pulverize all oxidizer before reacting with the toluene. That way, no benzoic acid will be generated when the mixture is heated to drive off any excess solvent.
Another may be to use a more inert solvent (i.e. diethyl ether)to remove the residual toluene before heating it up. That way, the ether should just boil off without reacting with any excess oxidizer still in the mixture.
Or perhaps, the normal technique I've been using could be applied, the benzoic acid is allowed to form as usual during heating, but is extracted out with another (inert) solvent just before regeneration. I dare say that another possibility would be to apply a vacuum to the mixture to drive out excess toluene, intead of heating it!
As soon as I have found a working way around this (and it will be soon), I will post more pictures.
frogfot Hazard to Others Posts: 212 Registered: 30-11-2002 Location: Sweden Member Is Offline Mood: happy posted on 1-2-2005 at 03:56
That was very interesting, CycloKnight. One thing I wonder, can you tell the amounts of MnSO4, (NH4)2SO4 and 60% H2SO4 that you've used to prepare manganese ammonium alum? It's quite ignorant question but I'm low on the precursors and wanna do this with bigger yields.. Also the patent didn't describe this in detail eather..
If I understand correctly manganese ammonium alum is MnSO4*1/2(NH4)2SO4, right? Couldn't one than simply use a mixture of these two salts? They dissociate in water anyway.. Extracting with a solvent would be very convenient nearly for anyone.. Instead of ether one could use ethyl acetate of low boiling petroleum distillate..
Only thing I could suggest to the synth is using a mechanical stirrer overhead instead of magnetic..
CycloKnight Harmless
Posts: 45
Registered: 4-8-2003 Location: United States of Britainnia
Member Is Offline Mood: Experimental
posted on 1-2-2005 at 12:30
For the manganese-ammonium sulphate mixture, the ingredients I have used are based on the patent ratios and are approximately as follows: 680g MnSO4
310g (NH4)2SO4 700g H2O 1850g 91% H2SO4
this requires approximately 120 amp hours to fully regenerate.
I made the mixture up by first adding the ammonium sulphate to the acid/water(the acid was added to only about half of the water) mix, allowing it all to dissolve. Then to that I added the manganese sulphate, the mix will then turn yellow as the manganese-ammonium sulphate precipitate forms. Then I added the rest of the water. One piece of advice here - grind up the manganese sulphate BEFORE adding it to the ammonium sulphate/acid mix. Or you will spend all night trying to get it to dissolve and form the precipitate.
I have learned that when reacting the final oxidizer and toluene, the reaction will take place in minutes rather than hours if the mixing is thorough enough. I managed to get the last batch to fully react within about an hour at 50 C by manually mixing the two phases quite aggressively with a nickel spatula.
Overhead stirring is definitely recommended. I don't yet have that as an option, but if I had it I would definitely use it. For a 2L size, magnetic stirring is quite insufficient and leads to long reaction times. Strong stirring is essential for scaling up.
This evening I was going to use ether to extract out the last of the organic acid (benzoic, mostly) from the mix, however I have come home to find that the cell is functioning just fine, several shades of pink darker that it was this morning - which is typical.
What I think I will do is make sure that ALL of the OXIDIZER is reacted before heating to drive off the excess solvent before regeneration (from now on). I will melt up a section of glass tubing, giving one end a flat surface so I can grind up all the little chunks of oxidizer, before doing the aldehyde reaction. That way no benzoic acid will form at any time (in theory, we shall see...).
My plan is to:
1) Let my cell regenerate as usual, should take another couple days at most.
2) Do the toluene reaction only this time make sure no oxidizer is left unreacted, accomplished by grinding up everything before doing the reaction. 3) Extract with toluene (or toluene hexane mixture) until no yellow/reddish tinge to the extract.
4) Heat it up to drive off the excess solvent.
5) Confirm that both A) no benzoic acid (or any other organic acid) was formed during the heating and that B) no oxidizable solvent is left in the mix. 6) Electrically regenerate.
7) Repeat steps 2-6 until my 5L pail of toluene/hexane is exhausted...
If this works, then that is a perfectly workable procedure, quite easy to scale up. If not, I will try using other solvents to finish up the extraction of the benzaldehyde and toluene, before regeneration. In a day or two, the cell should be ready.
Then I will do another run, and post lots of pictures!
Coincidentally, my 1Kg of cinnamon oil just arrived in the post today, the smell permeating the container has made my house smell wonderful. And, I've been trying to think up a use for my 1Kg of sodium carbonate for months, that I haven't even opened yet.
Yes indeed, if all goes well this place is going to smell like the magical cherry kingdom.
CycloKnight Harmless
Posts: 45
Registered: 4-8-2003 Location: United States of Britainnia Member Is Offline Mood: Experimental posted on 3-2-2005 at 13:37 Benzaldehyde Toluene oxidation... Take 3.
Okay, regeneration is nearly complete.
This will be the oxidizing mixture.
The toluene has been mixed with the oxidizer and has been heated to 50 C, the mixture will be mixed vigorously for the next 60 minutes.
Reaction is nearly complete.
All in all, I have about 80g of product, which still contains a little bit of toluene - but I won't redistill it - I'll gather it all up with the rest and then distill it all at once.
However, my interest has been shifted in two ways, in one way I'm really fascinated by the curious oxidizing powers of the dark red salt (manganese ammonium alum), and in another way I'm overwhelmed by the ease by which benzandehyde can be made from cinnamon oil! I'll post those pics in just a few minutes.
Anyway, I observed that there are ways the solid oxidizer can be isolated from the mix, then reacted on its own with the toluene to form a much more managable reaction mix. Judging by the odour generated by small amounts of oxidizer/toluene - it may even be more efficient - I don't know for sure yet.
It is possible to use a far lesser quantity of sulfuric acid, but it means that the mixture is a paste, not a liquid. But, the paste has a much smaller volume and hence can be "worked" in a small vessel with less labour than stirring a much larger two phase mix!
The dark red oxidizer can't be isolated on its own without decomposing, but large chunks at a time are easy to separate from the cell during regeneration (still wet with cell acid, of course). I'm quite sure
that an acidic slurry can be regenerated in a special cell (i.e. bottom of the vessel is the anode), making the reaction much easier - and less dangerous due to the lesser quantity of acid and hence better for scaling up!
As I type, my cell is settling. That is, the manganese-ammonium sulfate is settling to the bottom. I will later pour off the top clear solution and try to regenerate the manganese-ammonium sulfate paste in the bottom of the cell, it will be an interesting experiment.
The reason for the fascination is simple, this dark red salt produces benzadhyde on contact with toluene. Mix the two together at room temperature and the characteristic cherry odour is noticed almost within seconds.
I can't help but think "what a handy little oxidizer.."
Heat it up and it oxidizes to the acid, keep it at 50 and it oxidizes just to the aldehyde, for toluene at least.
I'm just not crazy about the large volume of sulfuric acid, manipulations involving this cell are dangerous. The acid is concentrated enough to dissolve cotton cloth ON CONTACT, if my 3L beaker cracked and shattered on my stove during heating, I'd hate to think of the clean up operation! What a mess.
[Edited on 3-2-2005 by CycloKnight]
CycloKnight Harmless
Posts: 45
Registered: 4-8-2003 Location: United States of Britainnia
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posted on 3-2-2005 at 14:38
Benzaldehyde from Cinnamon Oil.
Okay, this is my latest experiment, and let me say - it truly works wonders.
If you are looking for benzaldehyde, and have access to simple lab equipment, then you've got to try this one on for size. This procedure was posted by Mendeleev and reference to the patent was given,US Patent 4,716,249.
I had been hunting this procedure for a while, but never knew how it was done. Thanks Mendeleev. I ordered 1 Kg of cinnamon oil the same day.
This reaction converts cinnamon oil in high yields, my cinnamon oil cost me less than $30 for the Kg I ordered and contains close to 90% cinnamon aldehyde and I've used it for this procedure without altering it in any way. This procedure only requires refluxing equipment, water, sodium carbonate, and cinnamon aldehyde (cinnamon oil, cassia oil, cinnamaldehyde, etc).
I haven't yet isolated the benzaldehyde from the mixture, because I am running 3 batches, the third has just been started with 2 already complete. I will separate the benzaldehyde in one single step later on, I will report back the yield, and the extracton/purification method I've used.
As far as yields go, what I can say is that the distinctive cinnamon aroma has been replaced with a sharp, piercing benzaldehyde aroma - no mistaking it. I think I can smell a TRACE of cinnamon, so I'm sure it must be pretty darned good!
And this is what 60 grams of sodium carbonate looks like:
In the oil goes:
Now reflux for 7+ hours:
(don't forget to use a condenser for refluxing!)
It's really simple, set up your apparatus for reluxing. I've used a 3L mantle heater set up for reflux - the thermometer is not necessary.
I've boiled 2L of WATER in a kettle. Some of which is used to dissolve 60g of SODIUM CARBONATE, the rest will be added later. Once the sodium carbonate is dissolved, the solution is poured into the 3L 3 neck flask. Then the 200g of CINNAMON OIL is added. Then pour in the rest of the hot water.
Add bumping granules, set up for refluxing and gently reflux for at least 7 hours. Reaction done.
Extraction of the goods should not be a problem. Reportedy, the main by-product of this reaction is cinnamon aldehyde, whcih boils at 246 C. Benzaldhyde boils around 178 C. From literature, the reaction should produce a mixture of 70% benzaldehyde and 30% cinnamon aldehyde.
And it sure smells like it.
I'm hoping the separation won't be difficult. I think I'll simply going to have to recommission the 'ole vigreux column for this one. If distillation is ineffective, I will need to form the addition product to extract the benzaldehyde. I'm hoping distillation will do just fine, though I'll probably use vacuum distillation to minimise decomposition.
After I have finished the third reaction run, I should have produced around 350 ml of benzaldehyde.
I should then have just enough recovered cinnamon aldehyde to run another batch and turn 70% of that into more goodies. To yield 400ml - 450ml benzaldehyde, perhaps. And it is alot easier and quicker than the acid cell method - though you can't use this procedure to make formaldehyde...
I am very pleased that this reaction actually works - and from cheap, common cinnamon oil. Here you have it, benzaldehyde by the gallon - if that's what you want.
I'll report back the actual, final yield later on.
This reaction simply proves that things that seem too good to be true, aren't always. Though, I hope that making benzaldehyde from cinnamon oil isn't considered "cheating..".
On one hand the chemistry is magic, but then on the other hand, perhaps making cherry flavouring from cinnamon flavouring isn't so big a deal, I suppose... Any comments? [Edited on 4-2-2005 by CycloKnight] CycloKnight Harmless Posts: 45 Registered: 4-8-2003 Location: United States of Britainnia
Member Is Offline Mood: Experimental
posted on 5-2-2005 at 12:46
Cinnamon oil experiment update.
The cinnamon oil to benzaldehyde conversion experiment is not yet complete. So far I have extracted and distilled all of the product from the reaction mixture.
From the 600g cinnamon oil I started with, I've managed to obtain a 500ml RBF filled to within 1 inch from the top with crude product. The crude product is a mixture of benzaldehyde and cinnamaldehyde (and lesser quantitiesof other by-products).
What follows are the photos I've taken of the experiment so far.
This is the cinnamaldehyde fraction mixing with the benzaldehyde fraction in the 500ml receiving flask, this is the crude product. Perhaps this photo sums up why we all love organic chemistry the best.
The photo does not do it justice. To see this process occurring in 3 dimensions with all moving "swirlies" is more information than the human brain is designed to take in at one time. Total visual overload. I think it compares with even the best sunsets I've ever seen...Only this is smaller - in this instance a magnifying glass achieves wonders!
And it makes a good desktop theme, at least on my 17". I only wish I took one of higher resolution.
More swirlies..
Pure liquid glass. And again..
Anyway, some photos of the extraction process are as follows: Soon after the 7 hour reaction was complete.
DCM appears to be a more effective solvent than toluene for this extraction.
DCM extraction #1
DCM extraction #3
I repeated the above, 4 times for all 6 litres. So, that's 24 extractions...That took several hours to complete. That does not include the first extraction I did with toluene. I would suggest to start the extractions after each reaction, rather than waiting until the end, like I did. It's alot of work and time.
However, I did have some issues with emulsions which would only break after strong HCl was added, brine alone would not break the emulsions. I had to keep adding more solvent, until a decent separation occurred.
Have a look:
This one has just been broken and is on the retreat
Distilling flask at the end of the vacuum distillation:
I am unclear whether the cinnamaldehyde is degrading or if this is the other 11% of the cinnamon oil + reaction by-products. My diaghram vacuum pump needs overhauling, the vacuum is quite poor, the temperature in the above flask is well over 200 C.
This is why I have not carried out the final distillation of my product, it's just too valuable to risk. I will overhaul my pump, THEN do the final vacuum distillation. Distillation apparatus. The vigreux column was used for evaporating the solvents to minimise losses.
This is the pet store aquarium valve I use to control my vacuum distillations - it works very well. They cost about £1.20 each (couple bucks a piece) . They are used to regulate the air from aquarium air pumps.
[Edited on 6-2-2005 by CycloKnight]
CycloKnight Harmless
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posted on 5-2-2005 at 19:16
Manganese-Ammonium cell images
"You tell me man, I only work here." - Hudson, Aliens
These are what I call "anodemites".
They grow on the anode when the electrolysing solution is already saturated.
With the pasage of more current, the red spreads to envelope the whole cell, by which time the regeneration is complete. Another shot of the regeneration process.
The light coloured material on the electrodes is manganese-ammonium sulfate "silt" which has coated the electrodes during stirring. In time it will all be converted to dark red manganese-ammonium alum. What I would like to do, is make an electrode that covers the entire bottom of the vessel (anode) so that the oxidizer will form from the bottom up into a solid red mass of crystals, which can then be removed from the acid easily, to effect toluene oxidation with minimal stirring required.
Note the headline on the newspaper, that poor guy? [Edited on 6-2-2005 by CycloKnight] CycloKnight Harmless Posts: 45 Registered: 4-8-2003 Location: United States of
posted on 6-2-2005 at 14:26
Cinnamon experiment complete
Fractional distillation of the crude product has now been completed.
The fractional distillation was carried out under vacuum, and employing a vigreux column.
The vacuum I was pulling brought the benzaldehyde over at 85 C, and the cinnamaldehyde over at 135 C.
Britainnia Member Is Offline Mood: Experimental
Benzaldehyde coming over...
Thermometer reads 135 C. Column insulated for this fraction.
Benzaldehyde condensation in the still head.
Cinnamaldehyde collecting in receiver, in it's usual, rather vibrant form.
(cinnamon left, cherry right) Total product is :
200g benzaldehyde 128g cinnamaldehyde
The cinnamaldehyde fraction was collected until it just started to turn orange. Despite the colour, it is probably reasonably pure. The benzaldehyde is quite pure, the suspended bubbles are droplets of solvent that came over at the very start of the vacuum distillation.
The benzaldehyde fraction was stopped when the temperature increased from 85 C to 90 C. Everything from 90 to 135 C is in the cinnamaldehyde fraction.
There is very little cinnamaldehyde in the benzaldehyde fraction, but there is bound to be a fair quantity of benzaldehyde in the cinnamon fraction (few to several ml?).
Bumping was quite a problem during this vacuum distillation, even though the vacuum was constant, I had to stop the distillation 4 times, to add more anti-bumping granules. I used both glass AB granules and ground pumice AB granules. This could prove to be a problem for larger batches (distillations) when magnetic stirring is not employed. My electric heating mantles don't have magnetic stirring. Once the cinnamaldehyde has also been converted to benzaldehyde, the total yield should be around 300g benzaldehyde.
The yield isn't as high as I rather optimistically had hoped. However, I am very pleased with the way this experiment has turned out, especially considering that there are obvious ways the procedure can be improved.
This is the most benzaldehyde I've ever produced at one time, and from a first try! Improvements I'm going to undertake are as follows:
1) Distill cinnamon oil before using it in the reaction, I think this may really help to avoid emulsions forming during the extraction phase. Garbage in = garbage out. The non-cinnamaldehyde fraction of the cinnamon oil really makes a mess. The tar that is left after the distillations is completely insoluble in spirits, soluble in toluene, but far more so in DCM, which was used to remove it from the flasks. Removing the non-cinn. fraction (dark-brown/black) in the beginning will help to distinguish between reaction by-products and aldehyde that may be degrading at different times during the extractions. If product is degrading, it is important to narrow down the cause.
The crude DCM extracts of the reaction mix were not washed before distillation, so some sodium carbonate will have been present - this may have degraded a fair amount of product. The extracts were not washed because of the emulsions issue, if this is remedied by removal of the non-cinn. fraction in the beginning, then the extracts can be washed with good separations.
2) Use magnetic stirring during the 7 hour reaction. This is based on previous experience of reacting 2 phase mixtures during reflux, yields generally suffer markedly when proper mixing is not employed; reflux alone is not enough to break up those oily droplets.
I will need to make up an oil bath so I can use my mag. stirrer/hotplate during the 7 hour reaction. 3) Use of toluene will be avoided during the extraction. DCM will be used only.
By applying the above improvements, I think the overall yield for this procedure can be drastically improved.
[Edited on 6-2-2005 by CycloKnight]
chloric1 International Hazard
Posts: 1015 Registered: 8-10-2003 Location: closer to the anode
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posted on 6-2-2005 at 14:48
LOVE the picks
I understand fully about the beauty of the reaction! The pink chewed up electrode was a surreal site. Could imagine it as broken tabel leg encased in bubble gum or a stub of a human arm in the garbage disposal. YUK! But you bring a whole new meaning to digital photgraphy!
In the theater of life its nice to know where the exit doors are located.
Posts: 292 Registered: 3-1-2003 Location: California Member Is Offline Mood: Wondering
This thread is likley not even loadable to people on narrrowband.
\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
chloric1 International Hazard
Posts: 1015 Registered: 8-10-2003 Location: closer to the anode
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posted on 6-2-2005 at 14:56
Well Darkfire I ahve to agree about loading speed but these are pictures that only the finest resolution could do justice. Maybe Cycloknight could use smaller image size with the smae pixel rating. I know sometimes I take fine resolution in small sizes to email them.
In the theater of life its nice to know where the exit doors are located.
Eclectic International Hazard Posts: 725 Registered: 14-11-2004 Member Is Offline Mood: Obsessive posted on 6-2-2005 at 15:25
Why not steam distill the benzaldehyde and acetal from the cinnamon oil, base mixture as it forms? Anyone have an idea how much water is needed to steam distill 100g benzaldehyde vs 100g cinnamaldehyde?
CycloKnight Harmless
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posted on 7-2-2005 at 06:20
Benzaldehyde
Thanks for the compliments, I really enjoyed taking the pictures, I'll try to take more of future experiments.
I have a narrow band internet connection, although the first time loading the page is slow - it is quite accessible. Future visits to the page just involves loading the new picture(s) recently added. Each image is only about 150kb average. Maybe I should have put at the top of the first page "Narrow band users, stick the kettle on for a cuppa'. "
After all, a watched page never loads...
However, I will do something with the image size, from now on. At first I thought the pictures were expanded by this page, but it turned out to be the other way around.. For any detailed images that are best displayed in a large format, I will simply include the scipics link to click on. That should tidy things up a bit.
Eclectic, I believe that cinnamon oil itself is produced by steam distillation of the plant material, as are most essential oils. Steam distillation of the reaction mixture will distill out everything except the sodium carbonate and bumping granules.
However, if pure cinnamaldehyde was used at the start of the reaction, I'm reasonably sure steam distillation could be used at the end of the reaction to drive out the reaction products. But it would take at least a couple gallons of water (steam) to be put through each 2L quantity of reaction mixture to get out all of the aldehyde. This would be good for processing industrial sized batches, without consuming industrial quantities of solvents.
I may experiment with using a more concentrated solution of sodium carbonate, that way things can be scaled up greatly. I'm quite tempted to process 1L of cinnamaldehyde in 1 reaction just to see what happens. Or maybe 500ml to start with.
The same quantity of sodium carbonate would be added, just less water.
I'm curious to see what effect that would have on overall yield. [Edited on 7-2-2005 by CycloKnight] Eclectic International Hazard Posts: 725 Registered: 14-11-2004 Member Is Offline Mood: Obsessive posted on 7-2-2005 at 06:35
I'm thinking that the benzaldehyde would steam distill much faster than the cinnamaldehyde. The water layer could be automatically recycled back into the reaction mixture, and if the condenser temp was held at 30-40 C, the acetaldehyde should leave the reaction, forcing it to completion. Think of it as an azeotrope with water. It might be worth a test run to see what king of separation you get with a mix of water, benzaldehyde, and cinnamon oil. Also the patent recomends a surfactant, lecithin would be good for making food grade flavoring.
Eclectic International Hazard Posts: 725 Registered: 14-11-2004 Member Is Offline Mood: Obsessive posted on 7-2-2005 at 07:15
Also, the sodium carbonate is just a basic catalyst for the reverse Diels-Alder addition of water to cinnamaldeyde to split it into benzaldehyde and acetaldeyde. You could just as well start with a few tablespoons of baking soda (bicarb).
trilobite Hazard to Others
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posted on 7-2-2005 at 09:06
Retro-aldol, not Diels-Alder.
Eclectic International Hazard
Mood: Obsessive
CycloKnight Harmless
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posted on 7-2-2005 at 14:49
Increasing yield..
It would be good if it were possible to extract the benzaldehyde out as it forms, it would certainly increase the overall conversion.
But, if it is possible to get a near total conversion using simple means, then it won't be necessary to extract out the benzaldehyde. Perhaps stirring will result in a much higher conversion.
I will find out soon enough, this evening I distilled out the cinnamaldehyde from the rest of the cinnamon oil. Tomorrow, I will add the other 128g to the 300 ml (I haven't weighed it yet) I've just distilled. What do you folks think will happen if the dilution is decreased?
I'm considering reacting the roughly 430g I have left, in one reaction in a 3 L RBF. If I fill the 3 L RBF with 2.5 L of liquid, then that is a dilution of approx. 40%. I can also let it react for a few hours longer, I don't yet have any reason to think that would do any harm.
Any ideas?
Here are a couple photos I took of the cinnamon distillate earlier this evening: http://www.sciencemadness.org/scipics/cycloswirlies.jpg http://www.sciencemadness.org/scipics/cycloswirlies2.jpg [Edited on 7-2-2005 by CycloKnight] Eclectic International Hazard Posts: 725 Registered: 14-11-2004 Member Is Offline Mood: Obsessive posted on 7-2-2005 at 16:06
Use a surfactant and stir. More surface area between cinnamon oil and water should speed up conversion. Use hot water for reflux if you don't want to try the steam azeotrope distillation idea, as that will at least allow the acealdehyde to escape.
If you use a distillation column and distill off the benzaldehyde as if forms, you won't need to do an extraction or distillation later. You might need some way to return the upper water layer to the boiler automatically though. I don't have the composition of the steam/benzaldehyde at hand, and it could be a lot of water for a small amount of product.
CycloKnight Harmless
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posted on 8-2-2005 at 06:44
Benzaldehyde
If all goes well, I should have the last batch of cinnamaldehyde (to benza.)started this evening.
I'm leaning towards carrying it out using the higher concentration of sodium carbonate that I mentioned before. That would really speed things up. Could you imagine processing 3 litres of cinnamon oil? That would require a 7 hour reflux for 30 litres! With good mixing remember..
With these new concentrations, it would only require around half of that, not too bad.
I'm very much looking forward to see what kind of yields can be expected from now on using this more concentrated variation.
Things would be more scientific if I were to do exactly what I did before except this time apply the improvements I mentioned. I intend to apply those improvements AND using the higher concentration (less water).
If things turn out bad, it could be difficult to narrow down the cause.
But, I'm in a rather optimistic mood - go for gold shall I?
If anyone can see any reason why I could end up ruining all of my remaining cinnamaldehyde based on the changes I've proposed, please speak now, or forever hold your peace...
I'm going to use:
1) approx. 430g cinnamaldehyde 2) 125g NaCO3
3) >2L of boiled water
If I use 2 L of water, then I've more than doubled the concentration from before. Shall I start with say, a 10 hour stirred reflux? Or perhaps I should increase it to 14? Magnetic stirring will be as rapid as I can get it, as long as the stir bar remains stable.
I dare say, that it may be possible to increase the conversion rate, by adding a solvent to help dissolve the cinnamaldehyde (or the original oil). Such as 10% ethanol? I won't do that this time though, too many unknown variables.
Maybe next time, depending on the yield I can manage this time.
Now on to the toluene oxidation.
Just as a reminder to those just joining this page, MAA = manganese-ammonium alum, and MAS = manganese-ammonium sulphate. MAA is the dark red oxidizer. Yellow MAS is converted to dark red MAA in the acid cell when current is applied.
The toluene oxidation cell experiment is still ongoing, and will be for a while. However, I've been observing some rather bizaare things going on. I don't yet have any pictures of this. I am for the first time, now starting to find oxidizer masses growing on the cathode, this happened when the cathode was submerged in MAS silt. I have also observed little masses of oxidizer growing on the sides of the beaker...
Also, when the "anodemites" are allowed to form when STIRRING has been applied, the unoxidized silt gets "cemented" into the precipitating oxidizer as well, to form a wierd, solid conglomerate of MAA, and MAS.
Also, if the anode doesn't have any oxidizer deposit on it, then it takes quite a while for some to form.
But, if there is an oxidizer deposit already formed, then that deposit rapidly grows larger - towards the cathode, with the passage of more current. I think I may have found a simple, working solution for making up the oxidizing paste.
Basically, a saturated cell (dark red/violet, like blackcurrent juice) is used to turn manganese-ammonium sulphate into MAA which immediately precipitates out. My cell is saturated, any more MAA that forms, just precipitates out or forms on the anode.
Once the cell is made, enough MAS is added so that when enough current has been passed, you will have a saturated solution of MAA. If too much MAS is added, you will have MAA precipitate, so it is not a problem.
With the saturated cell made up, start oxidizing kg quantities of MAS, that was prepared earlier.
Once it has been converted to the dark red salt, pour off as much of the acid/oxidizer mixture as possible. Remove the dark red salt and store in a sealed acid-proof container until ready to use, then pour the cell acid (that you poured off) back into the cell.
Some of the acid will still be in the dark red "paste" you just removed, that is good since without it the MAA will decompose into MnO2 - but after a few runs there will be no acid left in the cell!
That is fine if you only want a few kg of MAA, but if you want to make more more - you will need to replace that acid, and make sure the acid concentration is unchanged. The occasional titration wouldn't do any harm to work out the acid concentration, over time it will be altered by moisture, and water loss due to electrolysis. I'm reasonably confident this will work, because it's essentially the same process I've been applying all along, only without the benzoic acid issues. But having to replace consumed acid, that's all.
So, you see - with this variation the saturated cell is just used as a "converter", converts MAS into MAA. This way, no benzoic acid is ever formed!
The cell is NEVER heated! Before returning spent MAA (not MAS) back to the cell, make sure it is clean, and free of organics or you will end up with the benzoic acid complications I encountered before. Avoid it. To clean up the MAS before regeneration, you can :
A) use low boiling solvents to clean up the mixture, then evorate at low temp. or
B) Use steam distillation just for cleaning up the mix, but you will lose some of your sulphuric acid. The loss isn't that bad actually, but over time you will have to keep replacing it. I haven't yet tried my pH meter to work out the cell acid concentration, I would have thought that 60% H2SO4 is right off the scale...
sulphuric acid solution.
Again, the same solution (saturated) can be used over and over for making larger quantities of MAS, I'm sure. Otherwise, you will make up you sulphuric acid, then precipitate your MAS (by adding MS to an excess of AS in sulphuric acid), and then what are you going to do with that acid solution, throw it away? Make some diethyl sulphate? Who knows. It would be good to be able to use the same acid solution for making up ALL of your MAS.
When I first made my cell, like I explained in an earlier post - I simply added MS to an excess of AS in the cell. My justification for doing this was this :
"Well, if I make up the acid solution and collect the yellow MAS precipitate, I need to keep it wet so I still can't weigh it to work out the exact quantity of oxidizer.."
But, if you use the acid solution, you may not know the exact quantity each time, but you can be pretty sure that it is reasonably pure. Again, and again and again - without building up ammonium sulphate in your cell. If ammonium sulphate precipitates in the MAS acid solution, then it should be obvious by it's colour.
However, I have 2 slight problems when it comes to scaling up: 1) I'm all out of MnSO4 reagent.
and
2) My transformer only puts out 2 amps.
I've been putting alot more than 120 amp hours to get a decent conversion. Probably due to organic acid that is still in the mix. Needless to say, I won't be heating my cell to drive off solvent any more. Heating just cause more problems than it solves..
Believe me, I would only be too happy to make a 5 batch, 5 Kg, double-regenerating cell system, working on a rotating shift. Everything would be recycled, and this process would run 24/7. Heck, the more cells the better.
[Edited on 10-2-2005 by CycloKnight]
CycloKnight Harmless
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posted on 8-2-2005 at 09:23
Mass Production
For mass production of benzaldehyde from toluene, the air oxidation of toluene isn't so bad. Probably alot easier for some than for others.
But if one wanted to go the electrochemical route, here is one way:
I should emphasise that this assumes recycling of the oxidizer. It is kinder to the environment to recycle the oxidizer, but not at all essential. It could be skipped if one were in a hurry, simply by following the steps outlined in the last post to make a suitable quantity of MAA for a single reaction - to make the desired quantity of benzaldehyde. That would shorten the following process greatly.
For 24/7 mass production, there are 9 main steps involved in this process, and some can be carried out at the same time (multi-tasking = good time management!), and others can be combined - more on that later. Here they are:
1) MAA regeneration. May contain many individual cells, working in shift, with say 1 complete every 2 hours.
2) MAA settling. Pour cell mix into acid-proof container container, it must be left undisturbed for at least several hours to allow the MAA to settle out at the bottom. This stage may be made up of a few containers, each holding one batch. When one is added for settling, one is transfered to the next stage.
3) Pour off the saturated acid/MAA. This liquid will now go back to the cell for the next regeneration. You will now be left with a batch equivalent of dark red paste, it will probably still have an inch of liquid on top, it will not interfere.
4) Put into storage container. It would be a good idea to make this container have a several "batch" capacity. So, lets just say that each "step" involves 1Kg batches. Then build up a "buffer" inventory in this storage container of perhaps a few to several Kg of MAA. That way, if an accident occurs or the power goes out, you can still process toluene 'round the clock; this inventory will act as a buffer for your system - though not essential. Steps 1,2 and 3 simply add to this container, remove oxidizer in portions you are able to react at a time, maybe 3kg reactions at a time will be possible? Probably easier than 3 separate, time consuming 1kg reactions at 50 C.
5) Remove predetermined portion of MAA from storage container, and place in acid proof reaction vessel. This vessel must be fitted with some form of overhead mechanical stirring. It should at lest have a partiall sealed top, to help contain odours (and minimise evaporation of your toluene). A large excess of DRY TOLUENE is added. A large excess will be necessary if you are going to use mechanical stirring. This stirring mechanism would not be hard to make, easy from a power drill and an acid resistant rod. A fast spinning axle with a small impeller should be good for really whipping up the reaction mixture into a toluene/MAA milkshake. (The lower the temperature this reaction can be made to happen, then the better it probably will be).
6) Solvent (with large amount of dissolved benzaldehyde) is poured off. You may wish to add additional toluene to extract out as much of the benzaldehyde as possible. Use the mechanical mixer for each extraction.
7) Washing the solvent. Wash with water to remove excess acid. You may wish to back extract this water to reclaim some residual benzaldehyde/solvent. You could use a different solvent for the back extraction to conserve toluene. The water extracts could be fractionally distilled to recover some cell acid.
***This benzaldehyde laden solvent is the output from this process, it is put into a storage container and is removed when practical to do so, for the distillation process.***
8) MAS is transferred to solvent removal stage. This could be a vacuum vessel, or some kind of evaporator, or a solvent extraction using a low boiling solvent. Preferably low boiling as in < 50 C low boiling, maybe a higher pb could be used, uncertain at this time. A combination of (low boiling point) solvent extraction with subsequent vacuum evaporation could be used, or just plain old evaporation in a lowe humidity area, on a large acid resistant sheet could be used? Lots of possibilities.
9) MAS goes straight back into saturated MAA cell solution (from step 3) for regeneration, in 1 or more separate cells.
***Distillation process is run under vacuum. The first distillation could be run at normal pressure to drive off the toluene, then what remains is transferred to the vacuum distillation stage. Even a rather small vessel could do this, it would not have to be very big. I'm sure even a 250ml vessel could handle the output from this process, unless your regen cells were pumping out one heck of a current...No need for large vac. vessels***
Okay, I bet you're thinking this all sounds kinda complicated, well - it doens't have to be. Some of the steps can not only run at the same time, they can be combined.
For instance, 1 very large single cell could be run with a large hold up, say a few Kg solid material. Then, 1 Kg at a time can simply be removed when needed for the reaction, and the expended oxidizer from the last reaction (MAS) put back into the cell when convenient to do so.
Using that approach solves alot of practical issues, it just means that the cell will never be 100% regenerated at any given time - but who cares? Just keep an eye on the colour of the mix, keep it a dark-ish red, and make sure you keep organic solvent out of the regenerating mixture.
That large cell could also be the settling tank as well. Just switch it off for a while, it will settle pretty good in just a couple hours - if you are in a hurry. A scoop can retrieve the red paste or sludge from teh bottom, it's not difficult, believe me.
For a large single cell, some kind of overhead stirring would be a good idea -though I'm unclear how essential it would be (at this time).
Chunks of oxidizer that collect on the anode could either be A) broken off and mixed EVENLY with the solid material or B) maybe collected and used as the oxidizer. This would avoid the need to switch it off.
It is perhaps worth noting that this roto-batch style process - like most processes - has it's continual process equivalent, I think people oten refer to that as "going technical" The continual process equivalent would use a MAA saturated solution of cell acid, that is pumped via the process equivalent of all the above steps/stages.
Only that instead of working with a solid mixture, you would be working with an acid solution (at some stages red, at others yellow), which is not without it's own set of challenges...ie. acid-resistant pipes, pumps, level regulators, flow controllers, etc. would need to be obtained.
Or the batch system could be miniaturised to produce benzaldehyde more regularly, only on a more manageable scale. Doing EVERYTHING in single individual stages is alot of work.
Although the above proposal may have a solid material (MAA and MAS) holdup of perhaps 8 or 10Kg, running 10kg batches in single steps would be a nightmare, and very slow. It would be frustrating doing nothing, but waiting for your 10kg to regenerate.
If you were actually able to work with 10Kg batches, you would be thinking, hey I could be reacting another 10kg right now, and then extracting 10Kg, and then washing... Maybe someone will actually do that, there's an idea?
10 sounds a lot better than 1.
Harmless
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Update
This is just an update on the reaction I started this evening. Chemical used:
~430g Cinnamon aldehyde 120g sodium carbonate 2L boiled tap water
The 2 flasks at the front contain (from left to right) cinnamaldehyde and benzaldehyde. At the back: cinnamonaldehyde (green, freshly distilled), undistilled toluene, and benzaldehyde from the last toluene oxidation run. Note the colour change of the cinnamaldehyde, it has changed from orange to burgandy, since it was distilled 2 days ago.!
Not as high tech as my Heidolph MR 3003, but it will do the job.
Bumping granules. Pumice granules are generally much better for oily mixtures. I found a large lump of pumice in a field, and smashed it to powder with a hammer.
(Glass left, pumice right)
A closer look at the oily mixture:
http://www.sciencemadness.org/scipics/2cyclooilydroplets.jpg A dude's eye view of the overall setup:
http://www.sciencemadness.org/scipics/2cyclosetup.jpg
[Edited on 9-2-2005 by CycloKnight]
CycloKnight Harmless
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posted on 9-2-2005 at 14:01
Cinnamon experiment #2, update
I refluxed the mixture for 12 hours straight. I started the reflux yesterday at 20:00,
and I switched off the hotplate at around 08:30 this morning. I came home from work at lunchtime and switched on the heating only for about 30 minutes and after work I switched off the stirrer at 18:30. Eclectic had suggested that I try steam distilling the mixture instead of using solvents to do the extraction directly.
This is what I'm doing just now.
There are many ways this could benefit the process.
If benzaldehyde distils off much faster than the residual cinnamaldehyde, then steam distilling will help to get the remaining cinnamaldehyde reacted. At this time, this does APPEAR to be happening. The magnetic stirring was a fairly subtle process, and I'm sure that any droplets that didn't get broken up overnight, sure are atomised now.
This is the reaction mixture just before I started the steam distillation.
A closer look at the mixed top layer after the reaction, just before the steam distillation. http://www.sciencemadness.org/scipics/2cyclotoplayermixed.jpg
This is an essential tool for steam distillation. It is just a bent glass tube connected to some rubber tubes, this makes it flexible and so won't get damaged by the very turbulent mixture. The tube is bent 180 deg at the end to prevent rather disturbing back pressures that are produced when a large bubble of steam is sudddenly released, this way the steam is always moving upwards through the mixture. This really helps to maintain a constant flow of steam.
http://www.sciencemadness.org/scipics/2steamdistillationtool.jpg Here is the overall steam distillation setup. I'm sure it fairly self explanatory. http://www.sciencemadness.org/scipics/2cyclosteamdistillation2.jpg Same again.
http://www.sciencemadness.org/scipics/2Cyclosteamdistillation.jpg The steam is distilling through at a moderate rate.
http://www.sciencemadness.org/scipics/2cyclo3neck2.jpg
Oily droplets can be seen running down the inside of the 1L volumetric flask.
A closer look at the oil droplets.
http://www.sciencemadness.org/scipics/2cyclooildroplets.jpg