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kaviaari
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The mixture has been refluxing for an hour and a half now. There is no potassium permanganate in the mixture whatsoever. I don't have acces to vacuum
source so I filter the MnO2 off with glass funnel and cotton plug. There is a somewhat large ammount of water in the mixture, so I think that a part
of it oght to be evaporated before adding the hydrochloric acid.
[Edited on 8-4-2007 by kaviaari]
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Sauron
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US Patent 2 853 054 (Brill, to Olin Matheson) describes oxidation of various compounds to arylcarboxylic acid using cobaltic acetate and O2 at 1 atm
and relatively mild conditions. Substartes possible include all three xylene isomers as well as mixed m- and p-xylenes, as well as others. What is
particularly useful is that the inventor describes many details of reaction variables when conducted on bench scale in an article in Ind.Engin.Chem.
which I have bundled with the patent. A ketone is used along with the catalyst and USP O2 but this is merely MEK which should present no difficulties.
The reaction time and temperature are very similar to those cited in the 1921 JACS article for permanganate. While it does require oxygen, the
procedure at least eschews the mess of MnO2, affords 93% yield and signals end of its induction period with a convenient color change (purple to dark
green). I think it deserves close scrutiny
[Edited on 9-4-2007 by Sauron]
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Klute
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Nice info...
Good luck filtering the MnO2 without any vacuum! Do at least a couple of washings in that case or quite alot of product will saty trapped in the
solid...
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Sauron
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Do yourself a big favor and get either a water aspirator or a hand operated Nalgene vac pump.
The former (also Nalgene) works best with cold water, which in Finland I bet is in good supply from the tap.
The latter, looks like a hand exercizer, come without or without gauge (without is cheaper) and works well. You will also have strong hands.
Then get yourself a few fritted-glass Buchner funnels (not Coors perf plate) in various sizes and porosities. And rubber adapters so you get a decent
seal between funnel and flask, connect vac hose between pump and flask and you will REALLY save yourself a lot of aggravation and wasted time waiting
for gravity filtrations.
------------
The dimethyl and diethyl esters of the three di-acids have bp's very close to each other and so are no seperative help.
The p-nitrobenzyl ester still appears to be best bet.
This ester is prepared from the sodium salt of the acid and p-nitrobenzyl bromide not the alcohol.
The corresponding p-bromophenacyl ester is prepared from the sodium salt of the acid and p-bromophenacyl bromide, aka 4-bromo-bromoacetophenone, a
very very nasty lachrymator. So I would avoid this one and make the p-nitrobenzyl ester instead. While it is also lachrymatory it is not in the
military/police tear gas category, while phenacyl bride is a famous one of those and its p-bromo derivative would give no relief.
[Edited on 9-4-2007 by Sauron]
[Edited on 10-4-2007 by Sauron]
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kaviaari
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| Quote: | Originally posted by Sauron
Do yourself a big favor and get either a water aspirator or a hand operated Nalgene vac pump. |
Overnight about 50ml of solution has passed the filter, this is really going to take some time.
I have a filtering flask, rubber adaptor and a buchner funnel but no vacuum source. I have been dreaming of a water jet pump, but I just can't find a
supplier for those. Mail ordering would be one option, but everything is somewhat expensive here.
I think that I could borrow an old jet pump from school, it has not been used for who knows how long.
[Edited on 9-4-2007 by kaviaari]
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Sauron
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Org.Syn. has a prep for p-nitrobenzyl bromide on a 250-280 g purified product scale starting from p-nitrotoluene (which is easy) and using Br2 as
brominating agent. File is attached.
p-nitrobenzyl bromide is expensive to buy at $1-2$2 a gram so I'd just make it.
Org.Syn also has a procedure to make p-nitrobenzaldehyde from same starting material, and obviously you could reduce that back to p-nitrobenzyl
alcohol with a judicious choice of red.agent. You could also do a Cannizaro rxn and obtain both the alcohol and the p-nitrobenzoic acid.
Then brominate the alcohol with HBr conc. or else NaBr/H2SO4, this alternate route is more work but may be useful if you can't obtain or make bromine.
Incidentally, if you get bored starting with xylenes, you can make terephtalic acid quite easily from p-cymene, 4-methyl-isopropylbenzene. This is a
constituent of oils of cumin and thyme.
Might spark your interest in monoterpenes and natural products chemistry.
The xylenes and the isomeric phthalic acids are boring industrial chemistry by and large, mostly plastics constituents.
[Edited on 9-4-2007 by Sauron]
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Klute
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Thanks for all this Sauron! Indeed the synth from nitro toluene is accesable, and the ester formation give an interesting little project all by it's
self.. I've only rarely stumbled on ester synthesis from acid salts and halogenoderivatives, so thta kind of a new feild to play in..
Can this method be applied to generally all esters formation?
I'm wondering is it could be possible to brominate benzylalcohol and then nitrate it, altough benzylbromide is as bad or worse then benzylchloride to
deal with IIRC. ANd I guess I won't be messing around with the bromo-phenacyl esters, we are getting enough lachrymatory gas as it is in my country :S
so no need to go looking for it
BTW penacyl bride a typo i guess, at first i thought is was some sort of trivial name  Funny one if it was
Yes, I'm already having a little interest in compouds in natural oils, but generally the price of these oils doesn't allow much different reactions..
Also a few of them are quite a mess to fractionnate, but at least it smells NICE in the lab (not the residu from vacuum fractionnating cinnamon oil though!) The smell issue might be a major reason why i prefer working on ketones,
esters and aldehydes than , for example, amines
Anyway, thanks for your efforts to sparkle my interest as you say, it is very appreciated. You would do well as chemistry teacher of some sort, take
that as a compliment!
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Sauron
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Yes I meant phenacyl bromide, best avoided. Yes you can brominate benzyl alcohol with HBr or NaBr/H2SO4 quite easily. BzBr is a little nasty but,
life's a bitch. IMO that procedure is probably a lot lkess nasty than bromination of toluene with the element.
Nitrating the benzyl bromide you will get both isomers and will need to seperate them but doubtless that is in the literature somewhere for guidance.
In fact the Org Syn procedure has a ref. to that in Annalen, so as long as your German is up to it (archaic chemical german at that) you should be
fine.
I am quite sure these are the mono-esters we are talking about as I suspect the di-esters MW would be high enough to push up the bp too much. It would
be nice if we could find the bp's of these esters (we have the mp's) in the lit si we can verify that they will in fact distill, and not decompose,
and be far enough apart. Because if not then all this is for nothing.
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