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garage chemist
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You can always use the impure TCCA to make chlorine, which would be the best use for it.
From that you can make chlorobenzene very easily.
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Nicodem
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| Quote: | Originally posted by IPN
Main reason to get the TCCA was to make chlorobenzene in large amounts to experiment with the derivatives of 2,4-dinitrochlorobenzene.
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You do not need to remove the Cu/Al sulfate additives for the electrophilic chlorination of benzene. These additives will do no harm. However, for the
benzylic chlorination of toluene you better make your self some clean TCCA. You might try another shop or another supplier before cleaning it by
yourself.
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Filemon
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| Quote: | Originally posted by garage chemist
An advantage of bromine is that benzotribromide cannot be formed. So you get nearly quantitative yields of benzal bromide when using a stochiometric
amount of bromine (don't forget that half of the bromine is evolved as HBr!).
C6H5-CH3 + 2 Br2 -----> C6H5-CHBr2 + 2 HBr
No special initiators are needed, just slowly add the bromine to refluxing toluene irradiated with bright light.
The disadvantage of bromine is that formation of ringbrominated derivatives is promoted, because the reaction will take longer and cannot be made as
hot as the reaction with chlorine (think about the boiling point of bromine).
So the produced benzaldehyde would have to be fractionated thoroughly in order to seperate bromobenzaldehyde.
It is also crucial that the toluene be distilled before use! Any iron contamination will totally screw up the reaction.
For industry, bromine is too expensive, so only methods using chlorine have been used.
But in the laboratory, bromine has the very important advantage of convenience.
All the reagents are liquid, and can be mixed in every desired proportions.
The ringbrominated byproducts can be seperated by fractional distillation, this step would be needed with chlorine too because of the formation of
benzotrichloride.
In the lab, bromine is the better choice.
[Edited on 15-11-2005 by garage chemist] |
Which the best way is of making that reaction? I had planned to use benzene like solvent for the generated HBr. Is a good idea?
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Filemon
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| Quote: | Originally posted by S.C. Wack
benzyl bromide and sodium nitrate: US1272522 |
Are there it has proven this method?
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jackson2004
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benzaldehyde is not really worth synthesising,
it is so easily available, no watched, at least no in the UK and quite cheap
benzyl bromide and sodium nitrate theory looks promising,
but benzyl bromide cost same as benzaldehyde anyway.
If fact i pay slightly more for benzyl bromide
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ewok_poacher
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| Quote: | Originally posted by solo
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] |
Has anyone tried this ??
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Siddy
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has anyone tried some thing like:
ALL IN SITU`
Toluene -1mole
Ca(OCl)2 -1mole (or just under)
MnO2 - 2-5moles
H2SO4 - 2moles (just enough to MnO2 > MnSO4)
Into a RB flask, refluxed with UV light for 10hrs.
Im thinking, the small amount of Benzyl Chloride will easily be oxidized to Benzaldehyde by the MnSO4 and as it is used the Benzyl Chloride
equilibrium will shift to produce more. Giving a higher yeilding methold for benzyl chloride. Remaining benyl chloride that isnt oxidised could later
be added to anther mix.
Any ideas?
p.s. im trying the benyl bromide + sodium nitrate first.
p.p.s. with the cost of phenylalanine whats the point of the about method? even if it did work.
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Antwain
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I can't see how that would work. And MnSO4 is NOT an oxidising agent.
Also, for chlorination, the equilibrium sits far to the right, I believe, and only the rate of reaction may be slow.
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roamingnome
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"Into a RB flask, refluxed with UV light for 10hrs"
in regards to UV lite which is always appealing, there is a paper that deals with the use of zeolites, toulene, and molecular oxygen under irradation
to form the aldehyde
since the reactant is traped in a cage it only takes one allowable pathway....
http://pubs.acs.org/hotartcl/chemtech/96/jun/jun.html
without the cage a mixture of products resulting from radical pathways results in alcohols and such. probabilty is played out in a distribution of
products.
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Siddy
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Ive read that, and similar zeolite based patents. Problem is, where can you get zeolite?
My, ALL IN SITU post was based on the original idea's of this thread, which i think are dead because of bad yeilds. Anyway, that reaction mix didnt
work (as you predicted).
How about this:
Benzyl Bromine + Nitromethane anion > Benzaldehyde + ?
n.b. nitromethane anion is prepared from nitromethane and base, NaOH.
Ive searched high and low and i think this is the first time its been written on the internet but it seams a documented method in books. McMurry
Organic and others.
There is no yield in McMurry, but ill do some testing and find out what happens. Thought id throw it up here before i start so someone else could have
a try.
Im going to use Br2 to make Benzyl Bromide with a equal molar weight added to toluene with presence of UV. No other catalyst. Also, HBr (b.p. -66C)
pipes (to release pressure) into dry EtOH. To make EtBr. (trying to kill 1 and a half birds with a liquid Br2 stone.
p.s. i dont know what the "?" is, i only just found this reaction and havent even written it down on paper.
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Ephoton
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your going to use nitoalkanes for what a simple somellet type reaction you have to be joking me
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Ephoton
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so much about uv and manganese how many have done it. some I know of me included. give it up unless you get the electro route down in my opinion
manganese is truly a shitty reagent to work with dirty on your hands.
dirty on your work surfaces dirty for forensics. they will love ya for eva. I must say that I am a bit attracted to the idea of persulfate oxidations
they sound rather neat and clean though I have yet to have on work for me.
ive always had the halide formation then sommelet work for me every time. its just the halegenation thats the problem. its smelly and its very very
irratating to the lungs nose and eyes. but im look at iodine these days.
honestly its fully recylable and thats got to be a plus even if its dear to get. got to love the fact that my horses are dumb asses and cant help
running into barb wire fences all the time.
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Siddy
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If there is a better method for Benzaldehyde, it would be used over nitroalkanes. Nitromethane is cheap (for me), so is NaOH, yes its using a lot of
precursers but the only other method is cinnamaldehyde, which is $200/L (for me).
A note on MnO2 reactions, just because you go to your hardware store and buy black cement dye, does not mean its MnO2, it could be a lot of other
oxides. I think very early on in this thread people where getting 0% benz. they probably had CuO2.
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Panache
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Ammonium Persulphate/Silver Something Toluene, 65C, 30mins
I remember reading somewhere in this thread or elsewhere about a method utilising ammoniumpersulphate (around 360g), toluene(around 60g), some 0.1M
silver something solution and stirring at 65C for 30mins.
I have all these chemicals at hand, and a desire for almond cordial, if someone can find the exact details (yes i have UTFSE but it sucks big cocks)
i will bash out a couple of trials tomorrow to satiate all those interested. Otherwise I won't. 8)
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LSD25
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This I got from a google result - Synthetikal:
| Quote: | Elbs Persulfate Oxidation Patent (IndoleAmine)
I think I have what you're looking for - the thing is called "Elbs persulfate oxidation" and uses ferrous, cupric and/or silver salt catalysts
together with sodium persulfate in the oxidation of toluene or (benzyl alcohol) to benzaldehyde....
Patent US4146582 "Process for preparing aromatic aldehydes and ketones", P.Maggioni filed Jan. 31, 1977:
page 4, example 9:
"p-Anisaldehyde
Ferrous-copper catalyst: Anisic alcohol (50g), ferrous sulfate heptahydrate (0.3892g), copper acetate (0.7783g), demineralized water (100ml) and
methanol (40ml) are placed in a reactor.
The temperature of the rection mixture is raised to 80°C and a flow of nitrogen is fed to the reactor under fierce agitation while drip feeding a
solution of sodium persulfate (103.4g of Na2S2O8 in 335ml of H2O). The reaction is complete within two hours. The products are extracted with diethyl
ether and, after evaporation of the solvent, 0.8g of anisic alcohol and 43.86g of p-anisaldehyde are obtained by distillation at 100mm Hg.
The yield of p-anisaldehyde with respect to the reaczted anisic alcohol is 90.5%."
...some time ago, a friend told me he had had this strange dream involving BzOH, some lab glassware, some turquoise and green salts and much of a
white, stinging oxidizing agent - and a buttload of BzCHO after the dream was finished - in retrospect I think his dream is just what is claimed in
the above patent...
The trick is that with toluene, a 2x molar excess of oxidizing agent is required, whereas with benzyl alcohol, only one molar equivalent is needed.
This makes me think the toluene would be oxidized to BzOH anyway before being oxidized further to the aldehyde, and that therefore Elbs persulfate
oxidations of hydrocarbons to aldehydes/ketones always proceed via an alcohol intermediate. But that's just my 2 cents.
http://l2.espacenet.com/espacenet/bnsviewer?CY=de&LG=de&...
This is from: http://www.synthetikal.org/hiveboard/arch/forum/topic/topic_...
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I also found the following on page 2 of this very thread:
| Quote: | Originally posted by S.C. Wack
... Looked up Kinetic's JCS ref. There were other oxidants in that article as well. Looked in CA and found some things. Found Beilstein (all versions
except online, stingy Uni), the sometimes helpful Richter's Organic Chemistry, and the Fiesers' Reagents... of no use. Looked strictly for
toluene->benzaldehyde without high temps and in English.
First in the JCS was PbO2. 280 g of it and 300 ml of H2SO4 (sp. gr. 1.52) were mixed in a lead vessel with ice bath cooling. CO2 was blown in to the
reactor. With stirring, 50 g toluene was added. This was steam distilled after 3 hrs and a 24% yield of benzaldehyde was isolated with bisulfite. They
got an 18% yield without the ice bath and with slow addition of the toluene. The temp got up to 40C either way.
Also in lead, 100 g MnO2, 300 ml of the 1.52 H2SO4, and 50 g toluene were stirred for 5 hrs. Less than 1% yield. Repeating with "freshly precipitated"
MnO2 and 6.5 hrs, a 5% yield.
Then 40 g toluene in 2X its volume of CHCl3 was added slowly with stirring to 140 g CrO2Cl2 in 200 ml CHCl3 on a cold water bath. After standing
overnight, H2SO3 was added with stirring, the whole was steam distilled, CHCl3 evaporated, and a 44% yield of benzaldehyde was isolated via bisulfite.
Their description of this Etard looks different than others that I have seen in the journals. BTW, when I mentioned the Etard earlier, I was only
asking for a ref specifically for DCM/toluene. DCM and other chlorinated solvents often work, usually not as well, on various substrates. The Etard
will give phenylacetaldehyde with ethylbenzene, and phenylacetone with propylbenzene. Styrene also gives benzaldehyde.
And last, they mixed 200 g ammonium persulfate, 500 ml 4N H2SO4, 2 g Ag2SO4, and 40 g toluene with stirring. Steam distillation and bisulfite gave a
78% yield of the aldehyde...
Obviously this is from here: http://www.sciencemadness.org/talk/viewthread.php?tid=2223&a...
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There is also this in another thread:
| Quote: | Originally posted by Polverone
In the second oxidation, I was much less careful with measurements. I used a "dash" of toluene, a "quarter jarful" of water, and maybe a further
"quarter jarful" of ammonium persulfate. I warmed the jar's contents and periodically shook/stirred them. The aqueous layer slowly turned a pale
orange, while the non-aqueous layer turned a progressively deeper red. There was a marked change as the aqueous layer reached the boiling point. I
decided that I really didn't want to boil the solution, but it actually boiled more vigorously after I removed it from the heat. I believe I had
achieved the runaway oxidation stage. Fortunately, I was able to fetch some cold water to dump into it before it got vigorous enough to boil out upon
the table. This effectively killed the reaction.
I smelled some very interesting scents coming from that mixture. There was an aromatic smell sweeter and lighter than toluene. The non-aqueous layer
mostly turned into floating chunks of red goo. The goo was soft and sticky like recently chewed gum, and needed a non-polar solvent to remove it from
the jar.
This is from here: https://sciencemadness.org/talk/viewthread.php?tid=410&p...
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Again in a later post on the same page Polverone gives a reference which would probably be a good place to start:
| Quote: |
no particular target
I am interested in making benzaldehyde, benzyl alcohol, and benzoic acid. Benzoic acid is easy. Benzaldehyde is probably the greatest challenge,
especially since I can't just buy it. Forbidden == interesting!
Benzaldehyde and benzyl alcohol can be made from halogenated toluene derivatives, but in practice the halogenation is messy and the product obtained
contains impurities. This is why other methods interest me, although I am not entirely disinterested in halogenation.
I made another attempt at oxidizing toluene using ammonium persulfate and a procedure from US patent 4,146,582. Unfortunately, in my haste I botched
the procedure. Nevertheless, the leftover reaction mixture has the smell of almond flavoring to it: there's definitely some benzaldehyde in there.
Next time I will be a good chemist and follow the directions more exactly. But I need to order some more equipment first.
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Maybe you should look for the patent cited above, it seems like a logical starting point, eh?
Oh, fuck it - you wanted to be spoonfed dincha?
| Quote: | EXAMPLE 5
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° 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).
This, somewhat unsuprisingly is from: http://www.freepatentsonline.com/4146582.html |
You'll still have to follow the link and register to gain access to the full patent (which has some additional information you should probably
consider), but registration is free so I assume you can do that?
[Edited on 2-3-2008 by LSD25]
Whhhoooppps, that sure didn't work
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Panache
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fomg i fove fou lsd25
fanks fery fuch
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LSD25
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Was that what you wanted?
I do get the use of the f-key, why is it so?
Whhhoooppps, that sure didn't work
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Panache
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lol, nothing meant withthe f treatment just sounds silly and funny.
yes that is the info i wanted, here is what happened when i used it
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.
Personally i think the 2hr reaction time may be a little long as the distillation flask had heaps of tar remaining in it after the vac distil.
I will perform a further trial after i have had another 340 coffee's as i will need more then.
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LSD25
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Hang on, 17g/0.5g = 34 not 340 - so theoretically you should need more a whole lot sooner than you seem to expect?
Whhhoooppps, that sure didn't work
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Ephoton
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does this have to be silver nitrate that is used. I would think that the nitrate is converted to sulfate
as soon as it is in solution does the nitric acid help oxidation ?
very nice work very low on smell
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Nicodem
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It only matters that the silver salt is soluble with the anion preferably inoxidable to avoid side reactions. Silver cations are the catalyst in this
reaction since the persulfate oxidizes Ag(I) to Ag(II) which is an extremely powerful one electron oxidant oxidizing toluene to the benzyl radical and
H<sup>+</sup>. The benzyl radical is then immediately oxidized further to benzaldehyde by the persulfate.
Silver nitrate just happens to be the most available silver salt with the appropriate characteristics.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Ephoton
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so no halides would be the rule here thanks nicodem
on second thoughts silver nitrate sounds like the best option
[Edited on 9-3-2008 by Ephoton]
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gvgole
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 The MnO2/30%H2SO4 method for the oxidation of bezylic alcohol has worked out
selectively over aromatic methyl oxidation into corresponding aldehyde in 50% yields.
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len1
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This is hard to fathom. Toluene is hard to oxidize, benzaldehyde oxidizes by just sitting in air. Yet the S2O8/Ag+ mixtures gets the tough job done,
but doesnt touch the benzaldehyde.
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Panache
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sry had house guests for awhile and have been touring them around the countryside.
the original reference used silver sulphate but i didn't have any and i knew silver nitrate into h2so4 solution would destroy the nitrate so i hoped
it would be ok. the reference quotes 75% yields but its workup is steam distillation, however i can't see the work-up being such a factor in the
yield, the next run i did i left for 30 minutes and the yield was the same so reaction time isn't the key it would appear.
if anyone has the actual paper could you link it as i only have that one paragraph abstract/reference lsd25 dug out.
and i thought one drop was ~0.05ml so my need for more is correct 340 coffee cups now x 2 because of the repeat, so thats like 640 cups coffee at 12
cups day around 3 months lol
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