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tapira1
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Alternative synth of benzaldehyde
You may use the oxidation of styrene with oxygen under TiO2 catalysis. TiO2 is a paint pigment that can be mixed with SiO2 (sand) to make it more
manageable.
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Siddy
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| Quote: | Originally posted by tapira1
You may use the oxidation of styrene with oxygen under TiO2 catalysis. TiO2 is a paint pigment that can be mixed with SiO2 (sand) to make it more
manageable. |
And what about styrene, how does one manage to get that?
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not_important
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| Quote: | Originally posted by Siddy
| Quote: | Originally posted by tapira1
You may use the oxidation of styrene with oxygen under TiO2 catalysis. TiO2 is a paint pigment that can be mixed with SiO2 (sand) to make it more
manageable. |
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Pigment TiO2 doesn't work very well as a catalyst, it's designed for pigmentation purposes and these days likely to have a crystal struction selected
for low catalytic activity to keep it from chewing up the paint body.
| Quote: |
And what about styrene, how does one manage to get that? |
Collect polystyrene. Thermally crack it to a mixture of styrene and other compounds, Fractionate that for reasonably pure styrene. Do a forum search
for styrene and you'll find both posting on getting styrene and on several oxidation methods to use on it.
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Baphomet
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Tapira1 is right. Why do you guys want to do everything the hard way?
Reference is here:
"Benzaldehyde synthesis via styrene oxidation by O2 over TiO2 and TiO2/SiO2"
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi...
TiO2 from a pottery store would more than suffice. It is not a catalyst per-se, but a polymerisation inhibitor. SiO2 can be had easily from
waterglass.
Styrene can be purchased by the gallon from hardware stores 
\"Who ARE you? You\'re like the drummer from REO Speedwagon - nobody knows who you are\" from \'Employee of the Month\'
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not_important
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| Quote: | Originally posted by Baphomet
Tapira1 is right. Why do you guys want to do everything the hard way?
Reference is here:
"Benzaldehyde synthesis via styrene oxidation by O2 over TiO2 and TiO2/SiO2"
...
TiO2 from a pottery store would more than suffice. It is not a catalyst per-se, but a polymerisation inhibitor. SiO2 can be had easily from
waterglass.
Styrene can be purchased by the gallon from hardware stores
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Well, first wrong on the TiO2, it is a catalyst and a well known one for oxidation at that. The process is a competition between polymerisation and
oxidation, the more active the oxidation catalyst the lest polymerisation byproduct. From that report:
| Quote: | | Styrene was oxidized by molecular oxygen over TiO2/SiO2 for the formation of benzaldehyde. At 70°C and 30 atm air with a styrene flow of 9.0 ml/h and
air flow of 120 ml/min over 10.00 g catalyst, styrene conversion of more than 40% with benzaldehyde selectivity of more than 97% was obtained.
Formaldehyde, phenylacetaldehyde, acetophenone, styrene oxide, benzoic acid, and minor polymer were found to be the by-products. The polymerization of
styrene was initiated by the radicals formed in the oxidative reaction. The addition of radical inhibitor nitrobenzene and/or the employment
of a catalyst of high specific surface area can promote the termination of the radicals, and hence improve the selectivity of benzaldehyde.
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Note that there's a bit of work-up needed, and a good condenser with 9 ml of styrene in 7.2 l of air per hour and 40% conversion.
Styrene has never been in any hardware store I've been in, even back when I could buy benzene, lead arsenate, and nitric acid in them.
If you have full access, you might have attached the article.
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Panache
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So easy!
Just blast your styrene away through your continuous 10atm, 100C reactor for your 7%yield, recycling all the shit that's unreacted, if everyone stays
online i'll quickly knock-up one of these babies and be back in a couple of hours to report.
NI you're a bastard! You got in to responding to this before me! i had to modify my sarcasm as you'd already used some of the material i was going
to!! Damm. Ha!
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Baphomet
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Bzzt negative. What do you think the bold part means? TiO2 does not catalyse the oxidation. It soaks up the free radicals to prevent formation of
polymer.
How can it be a 'competition between polymerisation and oxidation'?? The polymerisation is a direct consequence of the oxidation, indeed it cannot
occur unless the styrene is oxidised first.
The reaction conditions and workup mentioned are facile and would not provide much challenge for a chemist of average ability 
1L cans of styrene are still on sale in a famous hardware retail chain in my country as of, about one month ago..
\"Who ARE you? You\'re like the drummer from REO Speedwagon - nobody knows who you are\" from \'Employee of the Month\'
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Baphomet
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7%.. where did you get that from? About 40% of the feedstock is reacted on each pass with almost total conversion to benzaldehyde.
Pressure is no issue. As long as you take care to construct your equipment properly.
\"Who ARE you? You\'re like the drummer from REO Speedwagon - nobody knows who you are\" from \'Employee of the Month\'
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Panache
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| Quote: | Originally posted by Baphomet
7%.. where did you get that from? About 40% of the feedstock is reacted on each pass with almost total conversion to benzaldehyde.
Pressure is no issue. As long as you take care to construct your equipment properly. |
I must admit i got into the whole thing a little too much. It been a hectic day and the weather is finally warming after months of cold and i've been
a little silly today!!
You are quite right about being enthusiastic in relation to this method. I always forget that toluene is not freely available everywhere as it is here
in australia.
Also whenever i hear the phrase 'solid supported catalyst' i immediately think it not going to work as i spent two years once trying to replicate a
variety of these indian claims regarding solid supported catalysts and got absolutely nowhere. I swear the indians think that regardless of the
synthesis they will be able to improve on it using solid supported catalysts and a microwave.
An example
'.....Pb(10g) was moistened with water and ground into the previously prepared solid catalysts compound A, the slurry was subjected to microwave
radiation for 2x7min bursts, obtaining internal temperatures above 240C. After the seventh pulse the Pb turned to Au, the solid supported catalyst
was conveniently recovered after simply plucking out the gold nugget 'and used in 146274632758 subsequent equally successful trials'
The 7% thing was a mistake, the pressure, you are right its very acheivable, and steel is cheap, just make everything thick.
A copy of the paper would be good!! Its funny that benzaldehyde can be purchased pure in every supermarket, its just that the 2% solution only comes
in 20mL bottles.
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Baphomet
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I don't have the paper. But if you like the sound of it why not spring for the $31.50 and try it out?
Fluidised bed reactions are a little more complicated than using homogenous catalysts, I agree on that. But it's still possible to take most
continuous processes like this and turn them into batch runs. I mean, how much benzo do you need??
Note that if you end up using a batch 'pipe' method or similar, SiO2 is not required. So you don't need to worry about supporting the TiO2 because it
will settle out before workup.  Whereas in a continuous process it would be
advantageous to keep it in the bed.
\"Who ARE you? You\'re like the drummer from REO Speedwagon - nobody knows who you are\" from \'Employee of the Month\'
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madcease
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What is best way to extract the benz from Almond Essence. Do you think just distill layers till reach b or should one add dcm to the mix as im scared
the b will steam over with the water if there is any in the essence
??????? Maybe its just alc
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kclo4
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| Quote: | Originally posted by madcease
What is best way to extract the benz from Almond Essence. Do you think just distill layers till reach b or should one add dcm to the mix as im scared
the b will steam over with the water if there is any in the essence
??????? Maybe its just alc |
Hey you, make sense!
Probably could extract it by distillation or with bisulfite. http://en.wikipedia.org/wiki/Sodium_bisulfite
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Panache
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| Quote: | Originally posted by madcease
What is best way to extract the benz from Almond Essence. Do you think just distill layers till reach b or should one add dcm to the mix as im scared
the b will steam over with the water if there is any in the essence
??????? Maybe its just alc |
Flood the essence with water, the benzaldehyde will slowly seperate and form a small globule at the bottle of the sep funnel, conversely you can
extract with dcm if you are impatient.
The residual solution will always smell powerfully of benzaldehyde as benzaldehyde has a funny affect on the olfactory sense, being most potent around
0.1% in a water soltion/emulsion. Don't waste your time attempting to get it out as its pointless, unless of course the point of the excercise was to
to clear a waste stream of all benzaldehyde, then you should do it.
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madcease
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Have tried flooding with water but cannot see any seperation. Smells high of b so i know its in there.
Also tried distilling and it contains what i think is ethanol and then something else in which a really bitter taste comes over at about 80-90. After
that fraction added water to try steam distill with no luck of any oil in the water.
S*** is buggered and doesnt know if it steam distills with solvent as well as water so problem might be the b is going over before the water graction.
Is this possible?
Edit by Nicodem: No "swiming" or any other form of pretending illegal activity is allowed on this forum! Next time the whole post
will be removed.
[Edited on 8/10/2008 by Nicodem]
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Panache
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| Quote: | Originally posted by madcease
Have tried flooding with water but cannot see any seperation. Smells high of b so i know its in there.
Also tried distilling and it contains what i think is ethanol and then something else in which a really bitter taste comes over at about 80-90. After
that fraction added water to try steam distill with no luck of any oil in the water.
SWIM is buggered and doesnt know if it steam distills with solvent as well as water so problem might be the b is going over before the water graction.
Is this possible? |
Apologies i could have been clearer, the essence needs to be flooded with water until the polarity of the mix renders the benzaldehyde insoluble. This
will be evidenced byt he solution turning turbid and white. if this does not happen then the benzaldehyde concentration in your essence is very low
and what is there is soluble in water, a polar extraction will still remove it largely. In this instance steam distilling it should concentrate it
nicely, some will steam distill with the ethanol (remember ethanol distills over with water) but if you examine the partial pressures you will see it
steam distills poorly until the ethanol is completely removed. Once removed however it will steam distill over more quickly.
benzaldehye should burn your tongue but not really be bitter, it could be mistaken however as bitter
Perhaps a bisulfite is best however as i understand it len1 found the benzaldehyde adduct tricky, i have no experience with it.
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madcease
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Thanks Pananche but what ratieos do you consider flooding with water. Do you think i can just add DCM to the essence to extract or will that absorb
the ethanol contained.
Im pretty sure it distilled over with the ethanol as when tasted it burnt and tasted like b. But had no success when added water.
Can i just add DCM to the essence then extract or will it pull to ethanol with it?
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Panache
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| Quote: | Originally posted by madcease
Thanks Pananche but what ratieos do you consider flooding with water. Do you think i can just add DCM to the essence to extract or will that absorb
the ethanol contained.
Im pretty sure it distilled over with the ethanol as when tasted it burnt and tasted like b. But had no success when added water.
Can i just add DCM to the essence then extract or will it pull to ethanol with it? |
yes, the dcm mind you will distill with an azetrope of water also(and hence benzaldehyde), but its minor, ~ 2% water/98%dcm, i have often actually
wondered if this could be used to dry 96% ethanol.....2L dmc would theoretically dry 1L alcohol.
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brew
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| Quote: | Originally posted by Organikum
Some stuff from the-hive and an old patent:
| Quote: |
Toluene to Benzaldehyde by Manganesepersulfate
by: neograviton
(edited by me)
Here is a easy way to do it with Mn(V)sulfate. A way I used many time!
First get some MnO2. You can buy it as "Manganese-Black" a pigment for cement and concrete. Thats about 70% MnO2. Then put it in an equimolar amount
of H2SO4 (100%) and heat it up. Make it really hot. (>200°C). Let it be there for about half an hour. When I do this, I let The acid become so
hot, that white steam comes out. After that, let it cool down. You just have made Mn(V)SO4. It is soluble in 37% H2SO4 (battery acid) with a deep,
chocolate like brown color.
After that put it 1:1 with the toluene in about 60% H2SO4 (enough H2SO4, so that nearly everything dissolves). Heat (or cool) it to about 50-60°C and
stirr it well. After 3-4 hours you will have mostly Benzaldehyd (in my cases about 70%)
Distill the Benzaldehyd/Toluene out by a simple steam distillation. (Just boil water out, until there is no oily layer any more)
When you start boiling that stuff, the color of the liquid becomes sand-like. Thats because the rest of the Mn(V)SO4 breaks down to Mn(II)SO4.
And now the best: just put the liquid in a electrolytic cell (in the anode-part) and put some electricity through it, while stirring. The color will
chance to chocolate brown once again, and you can use it again!!! About 6 times!
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Hi, I am trying to work out the ratios for this reaction. Perhaps I am confused with the term equimolar. Disregarding the 70% for now. Mn02 is
86.9gmol-1 The acid at 98% with a specific gravity of 1.84gml-1 making it 1840gL-1 therefore 1840/98 = 18.7molL-1. So if I was to use 10g of the Mn02
which is 0.11 moles, (10/86.9 = 0.11 then how much acid should I add for this amount, surely it is not the same amount of moles, for if it was it
would come to a dismal aprox 6ml. This cannot be right, and I am obviously missing something very important. I was reading this, and am not ready to
do this reaction, but it didn't make sence and I thought I would queerie the instructions. Perhaps this is a beginners question and belongs in that
area, It obviously isn't a begginers procedure. I am wondering also if others have indeed followed this route for the production of this compound.
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brew
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Well I tried this reaction and used an excess amount of acid, 15g MnO2 with 80ml 98% acid.and it only turned into a grey sludge, I kept the temp over
200 deg for over 30 minutes and let it cool, and then added the 38% acid and no brown compound in sight, only the grey sludge as described. I used the
same cement black 70% Mn02 as described. I maintained a uniformed heat with constant stirring. Ive just ordered some other MnO2 with some other
material from a pottery supply place, so perhaps it is the quality of the manganese that is stuffing this up.Ill keep on experimenting, but if anyone
has done this, and can see the errors of my ways, it would be good to get some feed back.
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ItalianXKem
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need a aqueous solution of strong oxydizers
dichromates and permanganates
step one , make benzyl alcohol C6H5-CH2-OH
step two , oxydize carbinol , alcohol to aldehyde
1) reaction toluene and a oxygen donator (H2O2 , NaClO or other)
2) reaction benzol with strong oxydizing solution
H2O + X2Cr2O7 or H2O + XMnO4
X = Na , K , NH4
and benzaldehyde is maked !
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DJF90
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It really isnt this simple. If you cared enough to look through the whole thread you would see that a strong oxidiser on benzyl alcohol will yeild
mostly benzoic acid. An oxidising agent that is will only oxidise to aldehyde is needed, IIRC something like PCC (pyridinium chlorochromate), but this
is difficult to obtain for the amatuer chemist.
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Paddywhacker
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| Quote: | [quote by: neograviton]
Toluene to Benzaldehyde by Manganesepersulfate
Here is a easy way to do it with Mn(V)sulfate. A way I used many time!
First get some MnO2. You can buy it as "Manganese-Black" a pigment for cement and concrete. Thats about 70% MnO2. Then put it in an equimolar amount
of H2SO4 (100%) and heat it up. Make it really hot. (>200°C). Let it be there for about half an hour. When I do this, I let The acid become so
hot, that white steam comes out. After that, let it cool down. You just have made Mn(V)SO4. It is soluble in 37% H2SO4 (battery acid) with a deep,
chocolate like brown color.
After that put it 1:1 with the toluene in about 60% H2SO4 (enough H2SO4, so that nearly everything dissolves). Heat (or cool) it to about 50-60°C and
stirr it well. After 3-4 hours you will have mostly Benzaldehyd (in my cases about 70%)
Distill the Benzaldehyd/Toluene out by a simple steam distillation. (Just boil water out, until there is no oily layer any more)
When you start boiling that stuff, the color of the liquid becomes sand-like. Thats because the rest of the Mn(V)SO4 breaks down to Mn(II)SO4.
And now the best: just put the liquid in a electrolytic cell (in the anode-part) and put some electricity through it, while stirring. The color will
chance to chocolate brown once again, and you can use it again!!! About 6 times!
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I'd be worried about forming toluene sulphonic acid with all that acid, but maybe it is too dilute, but benzaldehyde is getting old, and anyway is a
reasonably available chemical.... not like some that are notorious precursors.
Has anybody used this oxidation technique on Xylene to give methylbenzaldehydes or even benzene with two aldehyde groups?
Or used it to oxidize anything else? Benzophenone from ethyl benzene sounds interesting, but what else can it do.
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brew
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| Quote: | Has anybody used this oxidation technique on Xylene to give methylbenzaldehydes or even benzene with two aldehyde groups?
Or used it to oxidize anything else? Benzophenone from ethyl benzene sounds interesting, but what else can it do. |
Yes, I was interested in this chemistry for other things such as formic acid rather than list 1 chem. I used the electro manganese, ammonium sulfate
route, I did it very small scale, and used a small amount of formaldehyde, I obtained from a friend. Once it reacts, it obviously stays in solution,
and one has to distill it, which resulted in a solution distilling over, at a bp, I cannot at the moment recall, and I reacted this with a base, and
obtained I believe sodium formate. Next time I do it, I will not be so slap dash with amounts etc and will determine yields. I also need to test the
mp of the salt formed.
[Edited on 28-2-2009 by brew]
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benzylchloride1
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I am currently working on producing benzaldehyde from toluene via the benzal chloride method. I started with 100g of toluene and 400g TCCA for the
chlorine source. I passed chlorine into the mixture for 7.5 hours. The mixture turned red and the final temperature of the reaction mixture was 181
degrees Celsius. The laboratory where this experiment was conducted was at an elevation above 8000ft. The refluxing mixture would boil at a much
higher temperature at sea level. I have distilled ethylene glycol with the same thermometer and the glycol boiled at 180 Celsius; its boiling point at
standard conditions is around 200 celsius. I distilled the mixture, much of the mixture distilled between 170-180 Celsius. I have prepared benzyl
chloride before and it distilled between 150-165 Celsius. There is a liquid residue in the 500mL reaction flask that I will transfer to a smaller
flask to obtain more of the product from it by distillation. The distillate smelled similar to benzyl chloride with more of a biting odor. Toluene in
my lab distills at 100 celsius. I plan to use the benzaldehyde in my synthesis of hexaphenyl benzene from toluene as the only organic molecule that is
incorporated into the final product. I am planning on running a thiamine catalysed benzoin condensation; I have conducted this with Loranne almond oil
and the reaction proceded with a yield of around 80%. Currently, I cannot obtain Loranne almond oil, it was a useful source of benzaldehyde.
Amateur NMR spectroscopist
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benzylchloride1
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I measured the density of my benzyl chloride, benzal chloride mixture. The density was around 1.18 which indicates that the chlorination is not
complete. I will set the chlorine generator up again in a few days to finish the chlorination. The benzyl chloride was not a problem until I cleaned
up the glassware. No chlorine smell was noticed in the laboratory due to the efficient hood and also because of the ground glass equipment. In the
meanwhile, I am trying the manganic sulfate oxidation of toluene using 1/4 of the amount of oxidizer that Cycloknight used. I am currently generating
the oxidizer using a 7.5 amp battery charger, the reaction that forms the oxidizer procedes very quickly due to the high current. What is the best way
to use this manganese compound for producing benzaldehyde?
Amateur NMR spectroscopist
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