Phthalic anhydride from Napthelene

ApprenticeCook · DILLIGAF

http://www.engin.umich.edu/~cre/08chap/html/runaway/example3.htm
and
"Oxidation of naphthalene with chromate or permanganate , or catalytic oxidation with O2 and a vanadium catalyst, gives phthalic acid."
From: http://www.all-science-fair-projects.com/science_fair_projects_encyclopedia/Napthalene

This process is done in industry making phthalic anhydride from napthelene, im interested in hearing from someone who can elaborate on the process of napthelene oxidation.
The pages i have so far found provide little information on the process other than that it can occur under permangenate oxidation and elevated temperatures... so im thinking this means above the temp phthalic acid forms the anhydride as that is the only mentioned product of the reaction.
2 Napthelene + 9 O2 --> 2 Phthalic anhydride + 4 CO2 + 4H2O
so im thinking...
Napthelene + MnO4^- --> Phthalic anhydride + MnO2 + CO2 + H2O
(its been a hard day at work so i cant seem to balance it.... Sad

)

The production of phthalic anhydride and the thus formation of phthalimide would produce a reagent suitable for the gabriel method of aminating alkylhalides (ie halosafrole --> MDA) for those of you who have noticed this is also on wetdreams where i was considering the oxidation of o-xylene.

The only problem as i have mentioned on that thread at wetdreams is that this reagent only produces primary amines ie MDA, it cannot be used to produce secondary amines ie MDEA, MDMA. However MDMA as per phikal synth from MDA is possible, check phikal page on MDMA.
It was also mentioned that sacchrin an artificial sweetner can be used as a gabriel reagent, it has the suited components and would work, however the paper i have refering to this method in phenethylhalides doesnt mention anything apart from they can be used....
For those of you who are interested in this, once you have phthalimide you produce the gabriel reagent potassium phthalimide by reacting with KOH (liberating water) then its a 3-step process from safrole --> MDA:
1) Halogenation of olefin
2) Connection of gabriel reagent
3) Acid decomposition of gabriel connection to form amine and phthalic acid (which could be recovered and re-used to form phthalimide!)

Just puttin this out there for interested parties...
-AC

EDIT: had to edit the incorrect thread title and moved to essential methods, not the correct forum.
-AC

Esplosivo · Mon Feb 28, 2005 9:46 pm

According to Organic Synthesis the alkaline oxidation of naphthalene with potassium manganate (VII) yields 2-(carboxycarbonyl)benzoic acid which on treatment with NaHSO3 and then HCl is converted to phthalaldehydic acid which can then be converted to phthalic acid. I carried the first step of the process out some time ago. The oxidation of naphthalene proceeds easily. But due to time constraints I had to stop my experimentation. I don't know if a stronger oxidizing environment, such as acidic KMnO4 would oxidize the naphthalene directely to phthalic acid. Any comments on the latter? Would simply heating the phthalic acid dehydrate it to give the anhydride (as in the case of maleic acid, for example)? Thanks.

ApprenticeCook · DILLIGAF

Hey,

Yeah in vogel 5th edn they give reference to CrO3 oxidation of Napthalene to 1,4-Napthoquinone (Pg 1022) and the formation of the 1,4-Napthoquninone photodimer (Pg 1125).
But the resources i have found show that hard oxidation will form phthalic acid so yeah maybe acidified permangenate might do it... might get a bit messy though... control would have to be an issue.

Phthalic acid is converted to Phthalic anhydride at:
"Melting Point: 230C (446F) Forms anhydride and water "
http://www.jtbaker.com/msds/englishhtml/p4270.htm

-AC

Guest · Thu Mar 03, 2005 6:32 pm

I knew there was a use for Napthalene,
I'd once hoped that a benzoquinone synoanalogue could be made from Napthalene, like napthaquinone, etc,

I am just happy now, that all that time, walking down the supermarket isles, is not wasted,

To make say boric acid into boric anhydride, heat is applied
I wish it was that simple for Acetic anhydride, simple heating of acetic acid to degradation,.

syn

methylenedioxy · Wed Mar 30, 2005 12:12 am

did somebody really knows how to oxidize naphthalene in the lab with permanganate/bichromate? I want to oxydize 1,4-diBr-naphthalene to the correspondind phthalic acid/anhydride.

Dr.Bunsen · Wed Mar 30, 2005 1:26 am

Why don't you start with xylene? Phthalic acid can prepared by the oxidation of xylene with dichromate, permanganate , nitric acid or even oxygen.

http://www.orgsyn.org/orgsyn/orgsyn/prepcontent.asp?print=1&prep=cv3p0820

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0810

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv2p0135

or for Esplosivo:

http://www.orgsyn.org/orgsyn/orgsyn/prepcontent.asp?print=1&prep=cv2p0523

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv2p0538

methylenedioxy · Wed Mar 30, 2005 12:13 pm

I cannot start from xylene because 2,4-Br-xylene is almost impossible to make but 1,4-Br-naphthalene is a realistic goal - tetraline is side chain brominated to tetraBr ; with a base it gives 1,4-Br-naphthalene, which can be oxidized to the 3,6-diBr-phthalic a/a.