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transmuter
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benzaldehyde
Did another run with neogravitron method. Used a 25 ltr plastic bucket & fixed a drill with metal stirer over the top. Sealed with a garbage bag.
Yield ~ 400mls. 
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Organikum
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A 25 liter bucket? How much H2SO4 did you use?
/ORG
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garage chemist
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You may also want to look at this:
http://www.designer-drugs.com/pte/12.162.180.114/dcd/pdf/aro...
At page 236, various methods for the oxidation of toluene to benzaldehyde are described.
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transmuter
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Hey Organikum, sorry for the late reply.
Used 7.8 ltrs of H2SO4 & ~ 3 kg of oxidant. The process appears to use less oxidant than the CycloKnight/US 808095 approach which would be > 5
kg to get the same outcome.
Swim has tried to dream up a suitable diaphram for regeneration of the oxidant but the acid levels hinder using anything to conventional.
Without the ability to regenerate the process would have a relatively high running cost. The "CycloKnight" has a high startup cost but a low
running cost (when doing quantity).
One could regenerate enough oxidant with that process to output 1 kg with ~ 100 amps of current. Toroidal transformers are available from electronic
component stores & a couple of 500 VA's could be used in parallel which after rectification could provide the 100 amps needed at 4-5 volts.
The secondary windings would need to be replaced with less but thicker wire to handle the current.
Swim doesnt have any ideas to help with your H2O2 problem but maybe a different angle may work. US 3531519 does a conversion in small quantities the
handicap being the risk of benzoic acid production. Also - Organic Process Research & Development 1998, Vol 2, No 4, 261-269 - converts benzy
alcohol to aldehyde + other nunerous oxidations ( incl. THF to GBL ) via H2O2.
Now swim doesnt pretend to have a good background in chemistry but heres some thoughts.
It would appear that the common thread with the manganese methods is a temp. of ~ 50 C & a H2O/H2SO4 ratio of ~ 40/60 creating an environment
which minimises benzoic acid formation (an excess of toluene should also help).
If H2O2 was used in leiu of manganese compounds & drip fed into this environment at approx. 2-4/1 mole ratio of oxidant to reactant + ferric
sulpate or Br2 as a catalyistn then maybe ........?........?
Swim has no idea whether H2O2 would handle such an environment & evolve O in an orderly fashion or not. If it was viable it would have the
advantage of low cost & far smaller oxidant carrier solution being needed i.e. less H2O 7 H2SO4.
Does anyone know a way of converting ethyl nitrite to nitroethane other than the asbestos catalyst method ?
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UhhKaipShaltaBlet
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Is there any straight synth for benzaldehyde from Benzene ? I'm interested in it cause I have good access for benzene ant cheaply.
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Sandmeyer
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There is a paper on oxidation of 3,4,5-trimethoxytoluene to the corresponding aldehyde with Co(OAc)2–Mn(OAc)2 as catalyst.
Kitajima N., Takemura K., Moro-oka Y., Yoshikuni T., Akada M., Tomotaki Y., Taniguchi M., The Selective Liquid-Phase Oxidation of
3,4,5-Trimethoxytoluene to 3,4,5-Trimethoxybenzaldehyde, Bull. Chem. Soc. Jpn., 61(3), 1035–1037 (1988)
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S.C. Wack
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Just a little addition to the Mn acetate/toluene electro-abstracts. Can't believe I missed this before, the reference came from a book. I have a
feeling that I've seen this mentioned before:
J. Sci. Ind. Res. (India) 12B, 255-61 (1953)
which is abstracted in CA 47, 12056g (1953).
The book said that the yield of benzaldehyde was 80% and that the electrodes were PbO2. The abstract says Pb and does not mention yield or amount of
toluene. It also says that the H2SO4 used was 60%, temp 60-70C, current density 6.8 A/dm2, and the catalyst was Mn2(SO4)3.5H2O (10% by weight, of what
it doesn't say) promoted with 1% (mystery weight) Ce(SO4)2. Side products tar and benzoic acid.
Found out today (no previous warnings, signs, etc.) that the library has done away with the cards that non-students buy so that we can use the library
photocopiers, which also read university ID's. From now on, only students and staff can use the photocopiers, my non-student ID will not work.
The med school library never has allowed non-students to use the computers or check out books, and this is probably coming soon to the main library -
and maybe to a "public" university library near you.
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Ephoton
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benzaldehyde success not easy but high yeild
ok were to start.
I would rather go via side chlorination of
toluene then a sommelet reaction of the
benzyl chloride to benzaldehyde.
then I would steam distill the benzaldehyde out of the mixture.
to find exact synthesis info
well ask me and I will post or go to organic sythesis volumes and merk index
I will be hangging around to see what happens to the bees so ask and I will post.
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neutrino
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If you have anything to say (hard to tell with your grammar), please post it in appropriate thread.
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enima
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well the much _easier_ route would be an elb oxidation of toluene using a persulfate salt and a metal catalyst to yield the aldehyde in a 70% yield.
No nasty benzyl chloride, 1 easy step.
A bisulfite adduct could be used for the puritification of the aldehyde as steam distillation is tedious.
But then again who needs benzaldehyde? (those nasty amphetamine chemists thats who).
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solo
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Benzaldehyde synthesis via phenylalanine
Recently Wizard X found this little pearl and made it available over at WD..........solo
| Quote: |
Phenylalanine when heated in 5N sodium hydroxide at 110~115° for 5
hours, it decomposes forming benzaldehyde. |
...........as reported at,
http://www.ajinomoto.co.jp/amino/e_aminoscience/bc/amino_13....
[Edited on 27-7-2005 by solo]
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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S.C. Wack
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Yield? Why no Cannizzaro?
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trilobite
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Steam distillation to remove the aldehyde as formed?
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Sandmeyer
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Kornblum is another possibility.
See also: http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/h... for another method.
[Edited on 27-7-2005 by Sandmeyer]
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solo
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Don't know why this quoted reaction would work since we're starting out with an acid (Phenylalanine)......solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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S.C. Wack
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solo: My question was, why would the benzaldehyde formed not react with the conc. hydroxide the second that it is formed? There needs to be a little
experimental detail here.
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solo
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Sorry , I didn't understand the implied question.......I don't know as you can see the reference was given by a chemist working in a
pharmaceutical company.....maybe I'll write him and find out a bit more.......solo
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Antoncho
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Persulfate oxidations
Well bees....
SWIM recently tried that US patent where they speak of oxidazing toluenes with Na2S2O8 with MeOH as a co-colvent and Cu/Fe catalyst.....
Unfortunately, SWIM has no methanol so he tried to sbstitute it for a) AcOH b) DMF c) IPA.
With AcOH, the yield was like 10%, the chief product being benzyl acetate  That
is, as soon as BzOH is produced, it is esterified under the rxn conditions and can no longer oxidize.
With DMF ...... err...... when you mix DMF with persulfate solution, it heats up spontaneously within 10 mins and violently decomposes
Same thing happened with IPA - but SWIM decided to try it again adding IPA separately in portions. Yielded only 30%.
It turned out that ALL of the oxidant disappeared from the rxn immediately after addition (tested with acidic KBr) although with MeOH it's
supposed to last for 2 hrs more.
EtOH seems not to bee an option since upon contact with persulfate it produces acetaldehyde at once.
That is, all in all, it looks promising (i.e., don't mind the NH4/Na difference, i assure you), but methanol is the only solv't that could
work.
It;s heavily controlled in Russia and no matter how hard a bee tries, he can't get his hands on any. But i assume you guys don't have that
problem, do you?
Then i encourage you to give it a try. It's going to work.
Antoncho
[Edited on 22-10-2005 by Antoncho]
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garage chemist
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How about ethanol instead of methanol? That should be considerably easier to acquire in Russia (distillation from Vodka?). 
Interesting thing is that in germany you can buy all the benzaldehyde you'd ever want from chemical suppliers. It's non- regulated and non-
scheduled here. Are things so different in Russia?
[Edited on 22-10-2005 by garage chemist]
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Antoncho
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Ahem.... read my post carefully. I mentioned ethanol.
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garage chemist
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Ah, sorry. Didn't read carefully enough.
But very strange that methanol isn't oxidised while ethanol is. Those alcohols are very similar in their behaviour towards oxidisers!
Maybe only a very small part of the ethanol is oxidised to acetaldehyde while the rest can still work as a solvent? Acetaldehyde has a very strong
smell, even very small amounts give the mixture the characteristic apple- like smell.
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Antoncho
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I'd say it's not that strange, those alcohols are NOT very similar in their manner of beehaviour towards oxidants: MeOH is much more
resistant (being much more "electron-hungry" .
Anyway, the main point is - there's nothing to bee _talking_ about here - we won't know until someone tries this. The rest of the dicussion
is useless crap
If anyone wishes, i can post a write-up of SWIM's own experience, so that may bee of help.
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frogfot
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Any idea on how one could prevent the runaway (mentioned on synthetikal) of this persulfate oxidation?
I asked the same question on synthetikal without any luck...
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IPN
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Posted at Synthetikal by IndoleAmine:
| Quote: |
Just wanted to mention that Na2S2O8 oxidations of toluene behave really strange, seen from a kinetic point of view: a 5 mol persulfate oxidation of
toluene seemed to run nicely, until the chemist decided to intetionally crank up the heat control from 65°C to 80°C after having added all the
persulfate solution over the course of 2.5 hours (he really thought it would be a good idea). Result was a really incontrollable exothermic rxn that
kicked in suddenly as a certain temp. threshold was reached, resulting in a giant "whooosh" sound and maybe 3-4 liters of boiling
persulfate/toluene/MeOH/BzOH/BzCHO/water solution were shot to the ceiling in an arm-thick fountain,in a matter of 10-20 seconds (a 29/32 stopper was
blown off too, and the fountain actually spit out of the condenser AND one side neck too - frightening when you consider the rxn vessel nominal volume
of 5L..)
--Conclusion: better partition the Na2S2O8 solution into two equal parts when doing large scale oxidations - since the rxn proceeds via an OH
intermediate anyway, this means that you first make BzOH and then oxidize further to BzCHO in two steps. Also make sure to heat to at least 75°C
BEFORE dripping in any oxidant. Hopefully the rxn can be controlled better this way...
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I have tried this procedure as well but only got a very low yeild. Probably kept the persulfate solution (MeOH/H2O) too long before using.. 
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bio2
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...Any idea on how one could prevent the runaway (mentioned on synthetikal) of this persulfate oxidation? .....
Persalts undergo rapid decomposition at a certain temp and more slowly in contact with moisture. Alcohol also decomposes pesulfate.
There are two ways to prevent an uncontrolled reaction which work with perborate (decomp ca 65deg). Also if the Oxygen escapes rather than reacts
yields will be low.
The problem is an induction period which becomes uncontrollable if too much persalt decomposes at once. The perborate after say about 2moles needs to
be added in portions at the rate that sustains the desired temperature with adequate cooling. Running cooler and longer works well with perborate with
only tap water cooling needed.
The other method is as indoleamine indicated and I do know that this procedure works per the patent although the 90% plus yields may be exagerated. If
the reaction mix is heated to the decomposition temp before any persalt is added then there is no induction period and with portionwise addition
it's easy to control
the temp. Just remove the heat after it kicks in and place in a water bath with a bucket of ice available to toss in a little at a time.
The cooler, longer method works better for more sensitive compounds and less excess is needed due to minimized O losses.
With a little practice you can fine tune your technique using the method which suits the optimum temperature for your reaction.
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