heksogen
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phthalic anhydride
Could ftalic anhydride be made by oxidation of o-xylene with KMnO4 solution to make the ftalic acid and gently heating the ftalic acid?
[Edited on 5-2-2004 by Polverone]
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Nick F
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Normal route to phthalic acid is by oxidation of napthalene I believe, with permanganate or dichromate. But o-xylene will work, the only problem would
be finding pure o-xylene, without m-, p-, toluene, ethylbenzene etc etc etc.
I'm not sure how easy it is to make the anhydride - distil from H2SO4? I really have no idea. I'm quite sure it will need more than heat
though.
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Polverone
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IIRC, phthalic acid is one of those acids that will form water and the anhydride simply by being heated alone.
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unionised
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IIRC isophthalic and terphthalic acids won't dehydrate to the anhydride that easily. That might be the basis of getting the phthalic acid pure,
even if you start from a mixture of xylenes.
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Geomancer
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Does anyone know a direct route to phthalic anhydride from naphthalene without the mercury catalyst?
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Nick F
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Wasn't aware of a mercury catalyst  .
Can you briefly outline the method that you have? I suppose it's possible that a different TMC will work...
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Geomancer
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I'm on break now, so I might not get to a library for a few days. Basicly, it's an old industrial process using sulphuric acid (oleum?). I
think you just cook the acid and the hydrocarbon with mercuric sulphate catalyst. IIRC, this was a key step in the first commercial indigo synthesis.
I just read that that it can be done with O2 in gas phase as well; see that dye chemistry book Polverone has for details. The catalyst looks
awfully like that stuff axehandle made.
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heksogen
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I've got pure naphtalene:D
According to the topic,
Finally, I’ ve bought some napthalene as moth balls. My next problem is that I don’t know which oxydizer is best to react with napthalene
to form ftalic anhydride. I think KMnO4 is best choice, but is it posible to use 30% hydrogen peroxide solution ? mabye some catalist is needed?
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Turel
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Lots of comments
Responses in the order of sequence of posts being responded to:
heksogen: Yes, absolutely. KMnO4 oxidation of o-xylene would yield phthalic acid, and yes it can be dehydrated by heat alone. Keep in mind that this
will not remove other impurities that may be present.
The boiling points of the xylenes are distinct enough to remove two of them from the last through vacuum distillation. After oxidation, the remaining
two acids have different boiling points again if I recall correctly.
Pure o-xylene does in fact exist. However, it will cost you an arm and a leg, and you cannot store it for long. This is a big reason it costs so much.
Pure xylenes undergo photo-induced regional isomerization to produce mixtures of xylenes. Xylene is often also contaminated with some toluene and
mesitylene, leading me to consider the cause of the isomerization to be migration of the methyl functions to neighboring molecules, as opposed to
strictly migrating around a single ring.
Geomancer: CrO3/dichromate oxidizes naphthalene under heat to form a dirty mix of phthalic acid, anhydride, oxalic acid, glyoxalic acid, and other
things I cannot remember. But technically I suppose it works.
NickF: You can read the HgSO4 in H2SO4 procedure at The Hive. I was going to provide you with an exact link, but their migration to new hardware seems
to be complicating my searches. I assure you the process has been covered there, and has been known for several years.
heksogen: I'm not sure if H2O2 will work to completion, and if it does, I think greater than 30% strength will be needed.
[Edited on 1-5-2004 by Turel]
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Hermes_Trismegistus
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Does anyone have a line on the oxidation of Naphthalene with Sulphuric in the presence of a mercury catalyst.
I'd really appreciate a link here, protracted searching has gotten me nowhere but angry.
Today's forcast indicates a high probability of either a nap or a temper tantrum, (followed by a nap).
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Marvin
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German patent 91202.
If I am reading it correctly 100 parts napthaline in 300 parts fuming sulphuric acid containing 20% free SO3 (or 1500 parts sulphric acid monohydrate
and 50 parts mercury sulphate in the 1st example). Heated for 10 hours at 250C. Can someone confirm if example 5 with oleum uses a catalyst, mercury
or otherwise? Claims also mentions temperatures above 300C.
This is the gist anyway. I'll look at this again later in detail if someone better at german doesnt have a go. I'm not fond of mercury, if
there is a longer way of doing it that needs no mercury I'm interested.
[Edited on 24-10-2004 by Marvin]
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Polverone
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Fundamental Processes of Dye Chemistry, available from http://bcis.pacificu.edu/~polverone/, has a procedure beginning on page 100 (of the PDF) that uses a tube furnace with vanadium pentoxide on
pumice catalyst to oxidize naphthalene to phthalic anhydride. The claimed rate of production is not very high - 4 grams per hour - but the only
chemicals needed are ammonium vanadate to prepare the catalyst and naphthalene itself. It is claimed that the product is of high purity as-is if
instructions are followed exactly.
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Hermes_Trismegistus
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That is certainly an interesting synthesis,
You allude to another synthesis in that post you made outlining the procedure with the tube furnace.
The synthesis you allude to is one with sulfuric acid and mercury sulphate, unlike another, much wiser chemist, I have no qualms about working with
Hg.
But no tube furnace. Can you, by any chance point me towards this synth (I do not, unfortunately, speak german).
Yet I have high hopes of luminal before christmas.
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S.C. Wack
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You can find it by UTFSSE at the Hive, you don't have to log in or anything. [hint]naphthalene hg phthalic[/hint].
Phthalic acid this way, and its anhydride from it, are in the Systematic Organic Chemistry file that I scanned and uploaded to FTP#2, but no one has
read. There is also a copy of the same file recently posted at the Hive. Again, you don't have to be a member to access that forum.
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Hermes_Trismegistus
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| Quote: | Originally posted by S.C. Wack
You can find it by UTFSSE at the Hive, you don't have to log in or anything. [hint]naphthalene hg phthalic[/hint].
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Sonofabitch...Well, I searched and searched yesterday and couldn't find it. And I broadened my search terms until I used only naphthalene, I read
pages and pages.
but thank you anyway; I, at least will download your file.
XXX 000
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Meltonium
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Quote: Originally posted by Turel  |
Pure o-xylene does in fact exist. However, it will cost you an arm and a leg, and you cannot store it for long. This is a big reason it costs so much.
Pure xylenes undergo photo-induced regional isomerization to produce mixtures of xylenes. Xylene is often also contaminated with some toluene and
mesitylene, leading me to consider the cause of the isomerization to be migration of the methyl functions to neighboring molecules.
[Edited on 1-5-2004 by Turel] |
Do you have a source for this; I can't find anything mentioning this? I'm trying to isolate the isomers using azeotrope a and crystallization. What is
the way to store o-xylene so it does not degrade? Do the other isomers go through this degradation too?
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DailyInsanity
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Dude......................That was 12 years ago.
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zed
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Just a blink ago, in Chem-Time. Some of the same guys are still around, and there is still interest in the topic.
There is an active link now, most of "The Hive" was buried for a decade or so.
https://the-hive.archive.erowid.org/forum/showflat.pl?static...
Umm. Lots of former links seem to be dead.
http://chemistry.mdma.ch/hiveboard/chemistrydiscourse/000422...
[Edited on 5-10-2016 by zed]
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