| Pages:
1
..
11
12
13
14
15
..
26 |
len1
National Hazard
Posts: 595
Registered: 1-3-2007
Member Is Offline
Mood: NZ 1 (goal) - Italy 1 (dive)
|
|
Somehow I find that hard to believe given the Cannizzaro reaction - which is well known and normally proceeds under much milder conditions.
|
|
|
MagicJigPipe
International Hazard
Posts: 1554
Registered: 19-9-2007
Location: USA
Member Is Offline
Mood: Suspicious
|
|
I agree. Also, if it were that easy wouldn't that be the method of choice and be more wide spread?
I think the best method (other than oxidation of BnOH) is hydrolysis of benzal chloride.
[Edited on 4-9-2008 by MagicJigPipe]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
|
|
|
Fleaker
International Hazard
Posts: 1252
Registered: 19-6-2005
Member Is Offline
Mood: nucleophilic
|
|
The benzyl cyanide reference
Here is one taken from the literature. Apparently I was wrong about the yield; it is 77% rather than 75% of BzCN from phenyl alanine.
While this isn't related to benzaldehyde, I did offer the paper and several members have asked me for it so I will provide it here for their
convenience.
Attachment: Hiegel.pdf (95kB)
This file has been downloaded 5420 times
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
|
|
|
Shingoshi
Harmless
Posts: 49
Registered: 20-4-2008
Location: Salem, Oregon
Member Is Offline
Mood: No Mood
|
|
I just couldn't resist joining you guys. Although, that's not meant to be sexist  in the presence of women. Found this site looking information on azeotropic solutions of Trichloroisocyanuric-acid (TCCA).
Glad I found you!
Shingoshi
|
|
|
Shingoshi
Harmless
Posts: 49
Registered: 20-4-2008
Location: Salem, Oregon
Member Is Offline
Mood: No Mood
|
|
Yes, precisely
| Quote: | Originally posted by Sauron
Welcome
TCCA is a solid. So I am not sure what you mean by an azeotropic solution of TCCA.
Do you mean an azeotropic mixture (of two or more solvents) in which TCCA is soluble? |
Acetone and chlorine will make chloroform. I want to try mixing tcca with various solvents to produce special refrigerants. Using Ethanol, produces
another refrigerant as well. IRC, it's R-130.
Shingoshi
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
R-130 is 1,1,2,2-tetrachloroethane, moderately nasty stuff. Ethanol + chlorine source generally gives di- or tri- chloro-acetaldehyde, or chloroform,
depending on reaction conditions.
|
|
|
Shingoshi
Harmless
Posts: 49
Registered: 20-4-2008
Location: Salem, Oregon
Member Is Offline
Mood: No Mood
|
|
I admit, I don't have the skill most of you have...
| Quote: | Originally posted by not_important
R-130 is 1,1,2,2-tetrachloroethane, moderately nasty stuff. Ethanol + chlorine source generally gives di- or tri- chloro-acetaldehyde, or chloroform,
depending on reaction conditions. |
My assumptions are often incorrect.  But I am only concerned with having a mixture
with a very low freezing point.
Question: Should I start another topic, so as not to pollute this one? That's fine by me, and would likely feel better about that also.
Shingoshi
Ok, here's the new thread. http://www.sciencemadness.org/talk/viewthread.php?tid=10387&...
EDIT by Nicodem: Yes, please open a new thread rather than continuing this off topic discussion.
[Edited on 21/4/2008 by Nicodem]
[Edited on 2008.4.21 by Shingoshi]
|
|
|
Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
|
|
Accidental omission
| Quote: | Originally posted by Panache
Using a 1L beaker H2SO4 (98%, 100g) was poured into distilled water (500mL) with heavy overhead stirring, the temperature rising from 25C to ~42C.
Silver nitrate was added (2.15g) followed by toluene (40g) and heating begun. The temperature rose steadily over the next several minutes to 51C where
it began rising quickly, ice blocks were added to the water bath around the beaker and the temperature rise was brought under control, after some 25
minutes the solution was at 65C and held here for a further 90minutes.
Stirring was ceased and the contents were poured over 300g of ice and the contents extracted with two portions of 100mL of dichloromethane.
The benzaldehyde/DCM solution was dried with MgSO4, the DCM and residual toluene evaporated off.
The benzaldehyde was vac distilled without a manometer. One fraction at 52-55C was collected (the flask contents bumping heavily during this process).
The cloyingly almond smelling compound was found to have a bp of 177-179C and a density of ~1g/mL. Final mass was 17g or 35%yield, pretty shit really
but damm easy and reasonably cheap.
1 drop (~.05mL) was placed into my coffee (short black with 1 sugar) and it tasted damm fine albeit a little dimensionless.
|
I just re-read this post of mine and realised i omitted the oxidant (ammonium persulphate), 200g were used and added to the sulphuric acid solution.
Apologies.
|
|
|
Klute
International Hazard
Posts: 1378
Registered: 18-10-2006
Location: France
Member Is Offline
Mood: No Mood
|
|
It appears that the two articles Trilobite posted in Polverone's thread are not available anymore. Considering how complete the first is on the
persulfate/Fe2+/Cu2+ oxidation is, and that the other one does shed some light on the H2O2/Cu+ oxydation, I am attaching them.
Thanks alot to Trilobite for finding and sharing these articles.
Paper 1:
Electron transfert process: Selective syntheses of aromatic aldehydes of industrial interest by catalyzed-peroxydisulfate oxidation
P. Maggioni, F. Minisci
Chimica & Indus. (2), 61, 101-105 (1979)
[Edited on 2-5-2008 by Klute]
Attachment: Paper1.pdf (1.1MB)
This file has been downloaded 1281 times
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
|
|
|
Klute
International Hazard
Posts: 1378
Registered: 18-10-2006
Location: France
Member Is Offline
Mood: No Mood
|
|
Paper 2:
pH dependence in the Cu+ mediated oxidation of toluene by oxygen or hydrogen peroxide
Okunowski et al.
Rec. Trav. Chim., 109, 103-106 (1990)
(Sorry: forgot to attach file!  )
[Edited on 2-5-2008 by Klute]
Attachment: pH_dep.pdf (1.4MB)
This file has been downloaded 1397 times
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
|
|
|
LSD25
Hazard to Others
Posts: 239
Registered: 29-11-2007
Member Is Offline
Mood: Psychotic (Who said that? I know you're there...)
|
|
I just finished reading the attached article about extracting BnO from aqueous solution and thought it would probably be of interest.
Of rather more interest to myself is whether or not strongly basic exchange resins (generally tertiary amines) could be used in place of hexamine in a
modified Sommelet reaction with Benzyl halide (Chloride/Bromide).
I was thinking this would remove the problems associated with phase-transfer one encounters with 2-phase reactions, the n-benzyl amine resin would
then be extracted rather simply by filtration. It would be interesting to see whether the benzaldehyde could be regenerated easily or not...
Any ideas?
Attachment: Recovery.BnO.fromAqSoln.with.ExchangeResin.pdf (425kB)
This file has been downloaded 2447 times
Whhhoooppps, that sure didn't work
|
|
|
manimal
Hazard to Others
Posts: 180
Registered: 15-1-2008
Member Is Offline
Mood: ain't even mad
|
|
Incidently, I wonder if manganese persulfate would oxidize ethylbenzene to phenylacetaldehyde/phenylacetic acid.
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by manimal
Incidently, I wonder if manganese persulfate would oxidize ethylbenzene to phenylacetaldehyde/phenylacetic acid. |
No, the benzylic carbon is attacked first, giving the aromatic ketone like acetophenone, or benzoic acid.
|
|
|
Siddy
Hazard to Self
Posts: 81
Registered: 8-10-2007
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by not_important
| Quote: | Originally posted by manimal
Incidently, I wonder if manganese persulfate would oxidize ethylbenzene to phenylacetaldehyde/phenylacetic acid. |
No, the benzylic carbon is attacked first, giving the aromatic ketone like acetophenone, or benzoic acid. |
Which is why you use Cr6+ instead.
Na2Cr2O7 + H2SO4 > Phenylacetic Acid
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by Siddy
Which is why you use Cr6+ instead.
Na2Cr2O7 + H2SO4 > Phenylacetic Acid |
I suspect that is not so, from
Oxidation of ethylbenzene with aqueous sodium dichromate
Donald G. Lee and Udo A. Spitzer
pp 1493 - 1495; DOI: 10.1021/jo01257a078
| Quote: | | Several attempts were made to find the proper conditions for the conversion of ethylbenzene to phenylacetic acid. In some twenty-four different
experiments the temperature was varied from 126 to 282", the time of reaction was varied from 0.5 to 12 hr, the ratio of oxidant to reductant was
varied from 2: 1 to 1 : 2, and the pH was varied from 5 to 11. However, in every experiment the only isolable products obtained were
acetophenone and benzoic acid. In general, long reaction times, high temperatures, low pH, and an excess of oxidant tended to favor the
production of benzoic acid, while less vigorous conditions decreased the amount of reaction and tended to make acetophenone the main product. Some
typical results are presented in Table I, no. 1-10. (Friedman and coworkers5 have also been unable to reproduce the results reported by Reitsema and
Allphin.z) |
|
|
|
Siddy
Hazard to Self
Posts: 81
Registered: 8-10-2007
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by not_important
I suspect that is not so, from
|
The method for the oxidation is very important -as with all oxidations. Just chucking the precursors in a flask and mixing probably wont get you PAA.
What your reference obtained is probably accurate. Commonly oxidations dont stop at the desired compound, you have to remove them as they form and
make a complex reaction vessel.
You will find a practical method at anyone of your drug site:
http://designer-drug.com/pte/12.162.180.114/dcd/chemistry/ph...
Note, the acetophenone obtained from a more simple approach can give PAA easily
|
|
|
Siddy
Hazard to Self
Posts: 81
Registered: 8-10-2007
Member Is Offline
Mood: No Mood
|
|
Has anyone had any luck with:
Toluene + Na(OCl)2 > Benzyl Chloride + Benzal Chloride
Benzal Chloride + H2O > Benzaldehyde
n.b. Na(OCl)2 could be any hypochloride salt
H20 could need -OH from salt, eg NaOH.
benzyl chloirde + H2O > Benzyl alcohol
benzyl alcohol [O] > Benzaldehyde
[O] = ammonium persulphate and conc. sulphuric acid.
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
Do you mean Sodium hypochlorite - NaOCl?
The relatively dilute aqueous solutions NaOCl comes in work against it in this case.
Earlier in the thread are discussions on using TCT, the current equavalent of hypochlorites in swimming pool applications. It can also do the
oxidation to benzaldehyde. Ring chlorination is a potential problem with chlorine based routes.
|
|
|
kalacrow
Harmless
Posts: 38
Registered: 23-5-2008
Member Is Offline
Mood: No Mood
|
|
General purpose oxidation, electrochemistry
I've found this thread fascinating, but most especially the bits given by Cycloknight early on. His excellent treatment of an electrocell is really
fantastic, and I was wondering if anyone could answer a question I had.
He states late in his posts that you could use the cell to simply generate MAA, remove it from the cell, put in more MAS and continue on. The MAA
could be reacted with your starting material outside the cell with "no heating".
Assuming you've worked out the molar amounts, would this simply be a process of:
1) measuring out starting material (let's assume we want vanillin from eugenol, so eugenol to start)
2) Combining it with the MAA
3) With stirring react over time until completion
4) Extract with low boiling point solvent
5) Heat the now depleted MAA (now it should be MAS) to drive off the remaining solvent
6) Save it to turn it back into MAA in the cell
Or.. do you need H2SO4 in there as a promoter? I'm guessing not. Also, in the particular case of eugenol -> vanillin, the classic case has you
isomerizing it before oxidizing.. would this be accomplished in situ here?
With a solid (at RT) starting product, would you simply dissolve it in an appropriate solvent to react? I'm assuming you'd need to be careful about
that solvent as you'd want one that was relatively impervious to oxidation by this material. Im also aware that this is a complicated question.. so a
general answer with one theoretically working example would be great.. not looking for case by case.. just the general theory!
Thanks very much in advance! Im fascinated by electrochem.. I've done all the basic stuff.. cl2, H + O2, and so on. Love the mechanism of it
[Edited on 9-6-2008 by kalacrow]
|
|
|
Siddy
Hazard to Self
Posts: 81
Registered: 8-10-2007
Member Is Offline
Mood: No Mood
|
|
kalacrow, PM Cycloknight he will answer.
AFAIK, no one was successful in converting Benzyl Chloride to Benzaldehyde in 1 step (without going though Benzyl alcohol).
Here is something i read, NOT ATTEMPTED though.
| Quote: | Strike
In a flask with stirring is added 126g benzyl chloride, 140g hexamine and either, 500mL 50% aqueous acetic acid or 500mL 60% aqueous ethanol. The
solution is refluxed for 2 hours, then 200mL 3N HCL is added and refluxing is continued for 15 minutes more. When cool, the solution is extracted with
ether, the ether washed 4 times with water, dried through NaSO4 and vacuum distilled to afford benzaldehyde (yield=70%). The two products are quite
fragrant which will give the chemist an idea of the success of the procedure. Did you know that a lot of methylamine is produced as a side product of
this reaction? How it can be salvaged Strike has no idea.
|
So Benzyl Chloride (easily made from toluene) can either be hydrolyzed to benzyl alcohol, then oxidized to benzaldehyde with Persulfate, or directly
from chloride to aldehyde with hexamine. Both are not particularly high yields, but as long as you benzyl chloride was easy enough to make who cares.
Alternatively, Len1's write up, advising Benzal Chloride from Cl2+Light radical chlorination of toluene, + HCl > Benzaldehyde.
NB: Benzyl chloride can be made from heating Toluene and Hypochlorite to 105oC, but not Benzal Chloride, it needs Cl2 (TCCA + HCl).
|
|
|
Ephoton
Hazard to Others
Posts: 463
Registered: 21-7-2005
Member Is Offline
Mood: trying to figure out why I need a dark room retreat when I live in a forest of wattle.
|
|
http://en.wikipedia.org/wiki/Sommelet_reaction
yes it has
methylamine im not so sure on as I think it goes through
benzylamine so I can not see how methyl amine can be produced.
it is truly an easy reaction just add water hexamine and reflux
for 2 too 4 hours. steam distill out aldehyde.
alcohol and acetic acid make clean up harder.
[Edited on 28-6-2008 by Ephoton]
e3500 console login: root
bash-2.05#
|
|
|
brew
Hazard to Self
Posts: 96
Registered: 25-4-2008
Member Is Offline
Mood: enthralled
|
|
I know this thread is to do with the conversion of toluene to benzaldehyde, but I found the following that produced this target compound along with
some other things that could be quite useful. I have purchased 250g of almond meal and due to not having a stirring device will not reflux it in
ethanol. Instead I will let it sit for some time and add heat and stir occasionally.
Amygdalin is extracted from almond or apricot kernel cake by boiling ethanol; on evaporation of the solution and the addition of diethyl ether,
amygdalin is precipitated as white minute crystals. Liebig and Wöhler were already able to find three decomposition products of the newly discovered
amygdalin: sugar, benzaldehyde, and prussic acid.[2] Later research showed that sulfuric acid decomposes it into d-glucose, benzaldehyde, and prussic
acid (hydrogen cyanide); while hydrochloric acid gives mandelic acid, d-glucose, and ammonia.[3]
The decomposition induced by enzymes may occur in two ways. Maltase partially decomposes it, giving d-glucose and mandelic nitrile glucoside,
C6H5CH(CN)O·C6H11O5; this compound is isomeric with sambunigrin, a glucoside found by E.E. Bourquelot and Danjou in the berries of the common elder,
Sambucus nigra. Emulsin, on the other hand, decomposes it into benzaldehyde, cyanide, and two molecules of glucose; this enzyme occurs in the bitter
almond, and consequently the seeds invariably contain free cyanide and benzaldehyde. An "amorphous amygdalin" is said to occur in the cherry-laurel.
Closely related to these glucosides is dhurrin, C14H17O7N, isolated by W. Dunstan and T. A. Henry from the common sorghum or "great millet," Sorghum
vulgare; this substance is decomposed by emulsin or hydrochloric acid into d-glucose, cyanide, and 4-hydroxybenzaldehyde.[
I will also be careful if indeed I attempt the decomposition with the potential hydrogen cyanide being produced. Perhaps this is a known method and
been already discussed. Perhaps not.
|
|
|
manimal
Hazard to Others
Posts: 180
Registered: 15-1-2008
Member Is Offline
Mood: ain't even mad
|
|
I tried to make benzaldehyde using the method from US780404 which uses a divided cell to oxidize manganese sulfate to manganese persulfate.
For the cell I used a gallon glass jar into which I placed ~1165 ml of 93% H2SO4 from drain cleaner and ~1478 ml of water, which should equal ~55%
acid if my calculations were correct. For the cathode compartment I used a small flower pot which I filled with the same acid mix and suspended in the
glass jar. I put into the jar approx. 450 grams of mn sulfate fertilizer, which I assume is the monohydrate (the bag says 31% Mn content, and Mn makes
up 32% by weight of the monohydrate).
I used a battery charger set to 6 V with no current control, which passed about 6-8 amps of current. I electrolysed the mixture for around 28 hours or
so, until it turned dark purplish black. There was a lot of undissolved sulfate at the bottom which would just resettle when stirred, but with
continued electrolysis it too turned brownish purple with white flecks.
When it didn't seem to be doing much else, I removed the electrodes and put ~250 ml of toluene into the jar. I used an electric eggbeater to stir it
around, and put it outside overnight to react. In the morning, nothing much had happened except that it had formed an emulsion. This was probably
because it had gotten quite cold outside (9 C) which had retarded the reaction. I then placed the jar on a hotplate set to low and commenced mixing. I
could smell the benzaldehyde within about half an hour. But after a long time (18+ hours) nothing much more seemed to be happening.
As you can see, it looks almost exactly like the first photo from Hilski's experiment (http://www.sciencemadness.org/talk/viewthread.php?tid=6882&page=3) with this method except that mine only has two layers. If the benzaldehyde
is in there, it's trapped in a wicked emulsion. The inside of the jar has the sweet smell of cherries and I can't detect any toluene, but maybe that's
because the benzaldehyde is masking the odor. Incidentally, the metal mixers from the eggbeater, which were unaffected after mixing overnight, became
badly corroded within an hour after I started warming the mixture. I coated them with epoxy, but after many hours even that started to dissolve. I'll
have to find some better mixers if I continue experimenting with this.
According to Hilski, his reaction was done in just 12 hours, but mine is still black, even though I used the same proportions of ingredients. Maybe he
used 450 g of the tetrahydrate, and if mine was the monohydrate I would have ended up with a greater mass of oxidant. I don't think significant
toluene would have evaporated. I'll probably try adding 100ml more of toluene and continue oxidizing till the mix turns sand colored. Does anyone else
have experience with this particular reaction?
Please excuse the shitty quality of my cellphone pic, k thnx.
|
|
|
Dr.3vil
Hazard to Self
Posts: 59
Registered: 27-7-2006
Location: Secret Underground Bunker
Member Is Offline
Mood: 4He + 8.7 MeV
|
|
electrochemical benzaldehyde
I mentioned this in a prior post (kolbe) but figured it needed to be here since the scope of the article is more about the production of benzaldehyde.
Attachment: reduction of aromatic carboxylic acids.pdf (438kB)
This file has been downloaded 3719 times
DR.3vil
- Paper chemistry works the first time every time -
|
|
|
HeilHamas
Harmless
Posts: 3
Registered: 19-9-2007
Member Is Offline
Mood: No Mood
|
|
Is vacuum distillation or distillation through a column necessary for the toluene/benzaldehyde mix? I tried simple distillation at atmospheric
pressure, and got clear toluene and toluene/water azeotrope, and distillate all the way from 85C to about 145C, however after that smoke and orange
liquid came through, that looked not unlike the pre-distillation liquid. Is that caused by high temperatures degrading the benz?
|
|
|
| Pages:
1
..
11
12
13
14
15
..
26 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
