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Author: Subject: toluene --> benzaldehyde
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[*] posted on 20-5-2011 at 20:04


Thanks heaps Sedit for bringing the patent to my attention again, more specificaly, thanks for bringing my attention to the nitric acid table as I didn't see this initialy. The yeilds are amazing and all the details of the reaction are revealed, including the reaction time.


Thanks heaps.
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[*] posted on 21-5-2011 at 08:20


I thought I had everything needed and was going to give this a shot but I seem to have mis-placed my Potassium Nitrate which I was going to use to make some Getto HNO3 and perform a test tube run. 74% yeilds with high selectivity is great if the patent holds to its word.

I don't really want to use Ammonium nitrate which I know I have because i'm concerned about the ammonia cation complexing with any formed Benzaldahyde. Who knows though. It might stabilize it and it might destroy the reaction. It also might not do shit but its not a varible I would like to change the first time performing the reaction.





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[*] posted on 23-5-2011 at 05:18


I started a little quick and dirty test tube experiment to see if I could detect the slightest smell of BnO but I quickly aborted it for reasons below.

I decided to make some nitric acid using H2SO4 and my ammonia nitrate even though I fear this could mess up the reaction a bit I wanted to try because I was bord. After making some crude nitric acid and adding some Iron sulfate I added some Toluene to it I started to run thru all the possible reactions side reactions ect as normal and quickly realized what I had just done. I had just added Toluene to an unknown concentration of Nitric acid.....

I quickly quenched it with water because of fear that Nitrotoluenes might form and the last thing I wanted to do is have this thing blow up in my face.

Later even with the lowered yeilds im going to start out with just H2SO4/Iron Sulfate/ H2O2 and see where that takes me.

It states a .1 molar concentration of H2O2... What percentage would that be if ya'll don't mind me asking? I never really learned much of concentrations using molar ratios and when I did learn it I would always forget since im more of a w/w or w/v type of guy.





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[*] posted on 23-5-2011 at 16:46


I have been pouring over this patent and I must say I feel it is legit. It does not have all the babble that BS patents normally have and it reads more like a science paper then a normal patent.

Now I have a question that you all more skilled in the art may be able to answer.

The best yeilds where obtained from Nitric acid at -1 - 1.5 PH and using Ferric sulfate as the source of the Trivalent iron compound. Sulfuric acid produces notibly lower yeilds on the order of around 20% less so it seems likely that the NO3 ion plays a good role. I have been woundering why the patent never uses Ferric Nitrate as the Trivalent iron source as it seems likely that it would produce yeilds on par or possibly greater then that of Sulfates.


Can anyone suggest a reason why they did not use Ferric nitrate? Its synthesis is as simple as Iron in nitric acid and it would mean that there is a coordination of ions instead of mixed sulfate and nitrate ions in the solution.





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[*] posted on 23-5-2011 at 21:40


A good question, I'm guessing its because metal sulfates are probably more comon and thats what they had when they were experimienting with the procedure.
I cant see any reason why ferric nitrate wont work either...
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[*] posted on 23-5-2011 at 21:48
benzaldehyde from hydrogen peroxide


Hey Sedit, the low yeilds you got with using hydrogen peroxide and sulfuric acid may be because you used the wrong concentrations, esp hydrogen peroxide.

In the patent it say that using sulfuric acid the yeilds should be around 50%...

two questions for you;

1) what yeilds did you get?
2) what were the concentrations?
3) what was the RPM of the stirring you applied?

With toluene type oxidations to benzaldehyde, these three factors are crucial and must be sufficient.
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[*] posted on 23-5-2011 at 21:59


Umm... you might want to reread everything I wrote to answer your questions. To start with... there are no yeilds?

I will perform these experiments in time and I really want to give HNO3 + Ferric Nitrate a shot but first things first and thats reproducing the patents results.

By all means the best way to go will be to use dilute H2O2 and slowly drip that in. I do not believe that acid concentration is very important just as long as you get it to the desired PH.



[Edited on 24-5-2011 by Sedit]





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[*] posted on 13-6-2011 at 23:43
yeilds of benzaldehyde


Hey guys I was just wondering.

I was reading the patent which uses hydrogen peroxide and ferri sulfate with nitric acic in a solution to oxidise toluene to benzaldehyde. They say the yeilds are around 74%. Now on the face of it, it seemed very impressive but I started to wonder exactly how the yeild of 74% was calculated.

Does this mean that with a yeild of 74% I should get 740ml of benzaldehyde out of 1000ml of toluene that I would add to a solution of 1000ml of hydrogen peroxide and ferrisulfate with nitric acid and water?

I'm trying to understand how this yeild is calculated so I can estimate how much product I would get. Can anyone help me with this please?
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[*] posted on 13-6-2011 at 23:58


I'm certain that if you read the patent, you'll find:
Quote:

The following examples illustrate the invention. In the examples, the yields given are based on the consumption of hydrogen peroxide on the assumption that 2 molecules of hydrogen peroxide are required to oxidise 1 molecule of the aromatic compound


Maybe you should read the whole patent before jumping into the experimental... you might find something interesting. I've often wondered how many patents are declared false by the amateur community just because the reader has failed to note something that was mentioned in the bulk text.
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[*] posted on 14-6-2011 at 00:44
oh!


ouch!!!

The yeilds realy suck then :(
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[*] posted on 14-6-2011 at 02:15


No, the yields are 74% - thats generally deemed more than "acceptable". Your issue is that this is not the yield based on toluene. The large excess employed (hydrogen peroxide is the limiting reagent) is likely to minimise further oxidation to benzoic acid.
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[*] posted on 14-6-2011 at 20:32


Then why dont they just put alot more ferric sulfate and hydrgen peroxide in it to make more benzaldehyde out of the toluene that is used, because 27g from 1000ml of toluene and 1000ml of solution is terrible?
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[*] posted on 14-6-2011 at 22:02


Why don't you try using more concentrated solutions/less toluene and find out?
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[*] posted on 15-6-2011 at 21:19


Going back to the 3rd page, would it be possible to form an adduct with cinnamaldehyde from cassia oil to further purify it from the essential oil to reduce the amount of garbage produced from the reaction.
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[*] posted on 16-6-2011 at 02:43
aduct


That would work but after the aduct forms and it precipitates out, you will still need to steam disstill the cinnamic aldehyde out, even if you were to add caudistic soda or even sodium bicarbonate to it.
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[*] posted on 16-6-2011 at 20:22
benzaldehyde from ozonosis of styrene


When you say that a typical ozone generator that one could buy from a store would typically produce about 2% ozone, how much ozone PERCENTAGE WISE do you think the method illustrated on the link below would produce?

It is the method where they have glued two pices of steel mesh to either side of a piece of glass and pass 5kV at 1 mA through it.

http://www.bigclive.com/ozone.htm
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[*] posted on 17-6-2011 at 11:37


I think ozone generators that use air as opposed to pure oxygen are limited to about 2 or 3 percent. As the concentration gets higher it decomposes more quickly via the O3 + O3 = 3O2 reaction.
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[*] posted on 24-6-2011 at 21:24


But on that website it says that it will produce a lot of ozone?
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[*] posted on 21-8-2011 at 10:08


Quote: Originally posted by questions  
Hey guys I was just wondering.

I was reading the patent which uses hydrogen peroxide and ferri sulfate with nitric acic in a solution to oxidise toluene to benzaldehyde. They say the yeilds are around 74%. Now on the face of it, it seemed very impressive but I started to wonder exactly how the yeild of 74% was calculated.

Does this mean that with a yeild of 74% I should get 740ml of benzaldehyde out of 1000ml of toluene that I would add to a solution of 1000ml of hydrogen peroxide and ferrisulfate with nitric acid and water?

I'm trying to understand how this yeild is calculated so I can estimate how much product I would get. Can anyone help me with this please?


The patent isn't very clear is it?
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[*] posted on 21-8-2011 at 10:21


100 mls., of aqueous phase, containing ferric sulphate (pFe=2), hydrogen peroxide (concentration 0.135 molar), and containing 1 gram. equivalent per liter of the acid stated in Table 4 below, were vigerously stirred with 100 mls. of toluene at 85C for 3 hours. Table 4 gives yield of benzaldehyde.

Nitric acid 74.5% yield
Hydrochloric acid 58.5% yield (what the?)
Sulfuric acid 55% yield

----------------------------------------Taken from US3531519

My main question is how much ferric sulphate is used? I do not comprehend (pFe=2) ?

If someone could help me figure out pFe=2 I would be greatful.
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[*] posted on 21-8-2011 at 13:04


Read the patent, I recall they define such terms.
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[*] posted on 22-8-2011 at 10:43


Ok so I have posted the EXAMPLE above and asked one question but that is not my only question. The example is worded in chemistry code. Most of this code is beyond what I have been able to learn because you tend to only learn this kind of stuff in college (college code kinda stuff). What I think I understand is this...

The aqueous solution has a total volume of 100ml. A solution of ferric sulphate is made with a pFe of 2 and set aside. 0.135 mols of hydrogen peroxide are measured out (4.14 in a syringe). Then a 1 gram equivilent per liter of the acid used is measured out(How do i find the one gram equivalent? ... ) Once the volume of the hydrogen peroxide and the acid has been determined and subtracted from 100 (100ml) you may then take the answer and take that amount from the solution with a pFe of 2 and add it to the beaker or flask then add in the hydrogen peroxide and the acid to reach a total volume of 100ml.


The 2 problems are...

how to make a solution with a pFe of 2?
what is the 1 gram equivalent of sulfuric acid?

[Edited on 22-8-2011 by MeSynth]

here is an example for the gram equivalent of sulfuric acid.

sulfuric acid has a molar mass of 98.078(5) g mol−1, and supplies two moles of hydrogen ions per mole of sulfuric acid, so its equivalent weight is 98.078(5) g mol−1/2 eq mol−1 = 49.039(3) g eq−1.

I am still unsure.



[Edited on 22-8-2011 by MeSynth]
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[*] posted on 22-8-2011 at 14:06


Screw it. The example below that one is easier to understand. here it is!

To 100 mls. of a 0.01 molar solution of each of the undermentioned metal ions, added as sulphates, in N sulphuric acid sufficient 65% hydrogen peroxide was added to make the solution 0.1 molar in hydrogen peroxide. This solution was stirred with 100 mls. of toluene for 3 hours at 85 C. the toluene layer was then analysed for benzaldehyde. Table 5 below shows the metal ions used and the yields of benzaldehyde.

ion yield, %
Cr3 36
Ti4 13
Fe3 56

Can someone help me and anyone else who is interested figure out this section of the example... The section in bold is the part in question.

To 100 mls. of a 0.01 molar solution of ferric sulphate in N sulphuric acid sufficient 65% hydrogen peroxide was added to make the solution 0.1 molar in hydrogen peroxide.


EDIT!

Here is the answer to the N sulfuric answer problem. and link

Eq wt x 100/% purity x specific gravity = 49x1000/98x1.84 =27.2
so take 27.2 ml h2so4 and make final volume to one litre = 1N

Read more: http://wiki.answers.com/Q/How_do_you_make_0.02N_sulfuric_aci...





[Edited on 22-8-2011 by MeSynth]
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[*] posted on 22-8-2011 at 14:50


I took the liberty. Here is what I came up with...

3.999 gm - ferric sulfate (anhydrous)
2.72 ml - 99% sulfuric acid
3.064 ml - 30% hydrogen peroxide (0.1 mol)
93 ml - DH2O

93ml of DH2O are placed into a 500ml round bottom flask along with a magnetic stir bar. To the H2O is added 4 grams of ferric sulfate (Iron III Sulfate Anhydrous) with stirring. Once the ferric sulfate has dissolved 2.72 ml of sulfuric acid is added slowly with cooling. After the addition of sulfuric acid and the tempurature of the solution is = to room tempurature 3.064 ml of hydrogen peroxide should then be added slowly. After the addition of hydrogen peroxide 100 ml of toluene is added. The mixture is stirred vigerously at 85 C for 3 hours. Remove the toluene layer. Extract benzaldehyde.

Edit... Or the hydrogen peroxide could be added to the toluene and the toluene / hydrogen peroxide solution could be poured in directly since heat at this point is desired.

[Edited on 23-8-2011 by MeSynth]
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[*] posted on 28-8-2011 at 12:33


In my last post I said that the conversion of cinnamaldehyde is the best route to benzaldehyde and that I dismissed it due to lack of cinnamaldehyde sources. This was a mistake. I now remember the best method to be the one bellow which is the oxidation of toluene. Very easy to do and quite fun. The hydrogen gas must be scrubbed before being vented. The fact is that everything can be recycled making this the very best. No waste (except for hydrogen thats why you must catch it in a scrub solution). I never got the chance to completely make the benzaldehyde from this reaction due to my beaker being discovered on the side of the house. I discovered it in the trash can. The things I enjoyed most about this where the colors and the smells and the visuals. The swirling of the purple into the white. It is just fun. I will eventually set up a cell but for now this is the post. Bringing it to the end for all you looking to find it easy.

Quote: Originally posted by CycloKnight  
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.


[Edited on 10-2-2005 by CycloKnight]


[Edited on 29-8-2011 by MeSynth]
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