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12AX7
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Synthesis of phthalocyanine
For organic chemistry II this semester, I chose to synthesize phthalocyanine for my project. Having seen it on this forum before, I wanted to see the
beauty for myself. And I like blue and copper.
Since this is such a blindingly simple synthesis, and I need at least two steps, I chose to synthesize an intermediate, phthalamide.
Reactions
1. Phthalic anhydride + NH3 ---(Delta)---> Phthalimide
C6H4(CO)2O + NH3 ---> C6H4(CO)2NH + H2O
5g phthalic anhydride and 4.5ml 28% NH4OH [I cringe when I see NH4OH, it's only 0.1% NH4OH! Why do people insist on calling it that?!] were placed in
a 25ml RBF and fitted with an air condenser. The flask was heated slowly over several hours on a sand bath, driving off water and fusing above 250C.
The material sublimates readily and deposits may form in the condenser, needing to be pushed down with a glass rod. The product is poured into a
beaker and cooled. Yield: 4.5g (90%). The product is practically pure without further treatment. The product was characterized with KBr pellet IR
and 1H NMR.
Figure 1. Crystals of phthalimide in the RBF and beaker. As it froze, the surface crystallized into a "hairy" mass of crystals. Sublimation
deposits consist of thin rectangular plates, sometimes in a wooly form.
2. 4 Phthalimide + 4 Urea + 1 CuCl2.2H2O ---(Delta)---> Phthalocyanine + CO2 + H2O + NH4Cl (unbalanced)
4g phthalimide, 1.58g urea, 1.16g copper chloride dihydrate and 0.01g boric acid (a catalyst) were added to a 15ml porcelain crucible and heated on a
sand bath to over 250C. As the urea melts and reactants give off water (absorbed or otherwise), the copper chloride turns green. Later, the reaction
begins to turn blue on top. A bubbling crust forms, which must be broken up and stirred with a glass rod.
Figure 2. Phthalocyanine synthesis, blue crust. Underneath, the reaction proceeds as a thick, slowly bubbling, deep purple material.
After about an hour near 300C and stirring several times, the reaction is nearly complete [or at least as complete as it's going to get]. The
reaction fumes of residual phthalimide (suspected), suggesting the reaction isn't complete, or the reactants aren't stoichiometrically balanced.
Figure 3. Complete reaction; glistening crystals of sublimed phthalimide cover the surface. The purple color is so deep, the camera sees only black.
This is as far as I have gone. Next week in the lab, workup.
The deep purple reaction product is ground up, washed with 10% NaOH, then 38% HCl, rinsed with H2O, then dissolved in H2SO4 and precipitated by
diluting 1:10 with H2O. The final ppt is washed with H2O and dried with Et2O. Yield: we'll see!
Tim
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unionised
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"28% NH4OH [I cringe when I see NH4OH, it's only 0.1% NH4OH! "
Well, don't.
Call it NH3(aq) (I think it's about 14%)
Anyway, a colleague of mine made some phthalimide accidentally. He was asked to find out what you got by heating a (polyimide, I think) resin in an
inert atmosphere. The blue stuff that sublimed out was accompanied by some yellow oily stuff but if you washed the filter with methanol the oil washed
off leaving the bright blue stuff behind. What I'm not sure about is whether he made the metal free compound or if it picked up copper from the short
length of Cu tube it went through.
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guy
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You forgot Ammonium Molybdate catalyst.
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Sauron
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Be cautioned that phthalimide is a heavy duty teratogen.
Unless you are like me and unlikely to sire any (more) offspring, use great caution around this stuff.
Sic gorgeamus a los subjectatus nunc.
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MagicJigPipe
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I always thought that teratogens could only affect women who could become pregnant. Does phthalimide cause sperm mutations or somehow transfer to the
female during sex?
I suppose it must be one of those because I can't think of any other way it would affect a women through a man except for the obvious cross
contamination.
If this is a dumb question, I'm sorry, but I haven't studied this area much.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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not_important
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A teratogen is an agent that can cause malformations of an embryo or fetus.
A mutagen is a substance or agent that causes an increase in the rate of change in genes.
A carcinogen is a substance that causes cancer.
Teratogens only affect a developing child through the mother's exposure, possibly pre-fertilization.
Mutagens can affect the germ cells of either parent-to-be, and thus a child conceived after exposure to the mutagen.
Carcinogens affect the exposed organism.
Substances can fall into two or three of those classes, generally high doses of a great number of compounds have a teratogenic effect.
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12AX7
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The MSDS at Aldrich isn't very specific. I haven't been eating the stuff, and most of it is now used up, so it's not a big hazard. The fumes are,
for the most part, contained in the fume hood (important, as this stuff does fume a bit at such a temperature!). Thanks for the concern though.
My reference showed boric acid is an acceptable catalyst, and my results obviously show I got a few grams yield. I'm not too worried about it.
In regards to backyard chemistry, I wonder if lignin would be an acceptable source of phenolic compounds for this reaction. It would be funny to cook
oak sawdust, urea and copper together and get a blue pigment!
Tim
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len1
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Very nice, pleasure to read
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12AX7
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The crude product was ground in a mortar and pestle (which may forever remain blue, I'm not sure!), leached with 10% NaOH, then 38% HCl. This removes
excess phthalimide, NH4Cl and copper compounds. The material was then "dissolved" in sulfuric acid and filtered over a glass frit funnel, which
resulted in deep green muck seperated from light yellow acid: evidently, this material does not dissolve in sulfuric acid as was claimed. The residue
was hydrolyzed, restoring it to a colloidial blue compound. The acid eluent contained no phthalocyanine, as it did not turn blue on dilution.
The precipitate was filtered and washed:
Yield: 1.1502g (dried), 29.4% of theoretical.
I may have to grind this up with some linseed oil and paint itself with itself on the wall of molecules. 
Tim
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Jor
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copper phthalocyanine
I want to make this stuff, because of it's said intense blue color.
Im doing the 4-step synthesis as described in Vogel.
-Make phthalimide with urea and phthalic anhydride
-Make phthalamide by 'ammonialysis' of phthalimide using conc. NH3.
-Making phthalonitrile with phthalamide and acetic anhydride.
-Make the copper compound using copper bronze and phthalonitrile.
I did the first step. It's very easy. Just heat the right amounts. it wil melt and at some point froth up. I washed with some water and filtered. I
had about 88% yield , some remained in the filter and I could'nt get it out.
At the moment, Im stirring (magnetic stirrer) the stuff with the right amount of 25% ammonia in the fume hood. I will do this for 24 hours. This si
2nd step.
But next is the acetic anhydride step. This is the tricky part. I have a liter of this, but this step uses 350mL for every 100g!. That's much more
than theoretically needed! Is this excess really necessary? Is there also another dehydrating agent possible? Ac2O isn't a really strong dehydrating
agent...
In the next step Vogel uses copper bronze. Why the copper bronze (contains some tin) ? Is just fine Cu-powder suitable? I guess it is, but not sure...
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hissingnoise
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Some here might see using Ac2O in pursuit of a coloured compound, however pretty, as the height of frivolity usage---but then, you may have what most
of us want---a secure, easy source for anhydride.
So, Jor, do you?
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Jor
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Yea I have enough of it , and could order another liter if I want. However, any amount bought will be registered, just as KMnO4, anthrallic acid,
piperine, NaF, cyanides and HF-solution.
Buying more than 100L will get the cops at the door however. Same for permanganate, buy more than 100kg and they will be here the next day. So it is
controlled, but not in 1L quantities. It's hard to find however, i was very lucky here : 1L for 15 EURO.
But even if they decide to completely regulate the stuff here, I can still buy a liter acetyl chloride for 25,00.... And some anhydrous sodium
acetate....
But, i hardly use it, so I don't feel guilty using it for a colored compound. But the amounts are quite hefty. What would you use it for then?
Aspirin, acetanilide? Other things I don't know? And no heroin please.
And because it's holy, I don't want to keep it here doing nothing with it because it's so precious 
I have it to use it, it's a reagent
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unionised
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I would be tempted to see what happens if you miss out the dehydration step.
A lot of things can be dehydrated by simple heating. If that works you can save the acetic anhydride.
Melt a bit of the phthalimide with some copper powder in a test tube and see if it goes blue.
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Jor
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Heating phthalimide is not going to work. Only one nitrogen in that molecule, while there are 2 in phthalonitrile. You probably meant phthalamide.
I will try it tomorrow. I will heat some. But I wonder if it works. By comparison, you actually need P2O5 to dehydrate acetamide to get acetonitril,
so that's not very promising, if I want to dehydrate 2 amide-groups in one molecule. But I will try it.
I will use copper, but I'm still wondering why Vogel states copper bronze. That's Cu/Sn...
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Barium
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The excess acetic anhydride is simply acting as a solvent. It is a damn good solvent and the excess speeds up the reaction. You can use acetic acid as
solvent containing 1,5 eq. anhydride instead. But I doubt the difference in price between acetic acid and acetic anhydride, when bought from your
suppliers, is that great.
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Jor
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I will use acetic acid as a solvent then. Even though acetic anhydride is available to me, it's still registered if bought. So I rather buy acetic
acid, wich is a little cheaper as well.
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Jor
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Heating copper powder and phthalamide does not seem to work.
I heated about 10-20mg phthalamide with a few mg of copper powder. There is a quite violent reaction, and gas escapes (water?). There is also a dirty
green solid on the side of the test tube, but no intense blue.
I will start tomorrow with phthalonitrile synthesis, with procedure from Vogel. I will use 10g of phthalamide, about 20mL acetic anhydride, and some
acetic acid. Vogel uses total volume of solvent 350ml for 100g phthalamide, so I will add 15-20mL acetic acid besides the acetic anhydride.
[Edited on 22-11-2008 by Jor]
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12AX7
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As my reaction shows, phthalimide and urea react quite well with copper chloride. Phthalamide should work fine alone (with production of HCl fumes I
suppose).
Phthalonitrile subject to radicals will tetramerize to unsubstituted H2Pc, or complex with just about anything on the periodic table (this is how e.g.
MgPc is produced). Radicals can be from UV, electrolysis, etc.
Tim
[Edited on 11-22-2008 by 12AX7]
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chemrox
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Acetic anhydride is not "registered" in the US as far as I know. My supplier keeps a file of declared uses for a wide variety of items the DEA has
interest in. Iodine and CCl4 are among them. These aren't the same as registration. What they do is ask for a verbal declaration or a faxed
letter of intended use. It's for their files. From talking with folks at DEA these never get looked at unless there's a criminal case.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Jor
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Exactly that's what I mean. We have to fill in a form for wich we will use it, not more.
I do not have copper chloride... Will copper sulfate pentahydrate (or maybe anhydrous) also work?
Im currently refluxing 11,7g phthalamide in 22-23mL acetic anhydride and 20mL acetic acid.
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Jor
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Im puzzled...
After 30 minutes reflux, the first white powder in the liquid is now bright yellow......
EDIT: another 20 minutes later the reaction mixture is ORANGE 
Anyone has an idea if this is normal?
EDIT2: After another 15 minutes, the reaction mixture is dark-red/brownish. I wonder what's going on. Acetylation?
EDIT3: The reaction mixture is BLACK now. I will reflux 1,5 hours more, and then pour everything in hot water, and make alkaline with NaOH. I will see
what happens.
[Edited on 23-11-2008 by Jor]
[Edited on 23-11-2008 by Jor]
[Edited on 23-11-2008 by Jor]
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UnintentionalChaos
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I've had a go at preparing Copper phthalocyanine and the results can be seen here: http://youtu.be/qvpK2Ie1pl0
For those of you not wanting to watch my rather long video, I did a microwave-heated fusion of phthalic anhydride, CuCl2, urea, and ammonium
heptamolybdate catalyst. Total heating time was only 5 minutes and 30 seconds. On workup, I got a 32% yield.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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ScienceSquirrel
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Quote: Originally posted by chemrox  | | Acetic anhydride is not "registered" in the US as far as I know. My supplier keeps a file of declared uses for a wide variety of items the DEA has
interest in. Iodine and CCl4 are among them. These aren't the same as registration. What they do is ask for a verbal declaration or a faxed
letter of intended use. It's for their files. From talking with folks at DEA these never get looked at unless there's a criminal case.
|
I am a licenced producer of alcoholic drinks for sale. I account for the malt used and the volume and ABV of the drink produced and I pay duty on the
drink and tax on the profit.
It is a highly taxed and regulated business.
There are legitimate uses for a lot of chemicals.
If you can show that the quantities that you are buying and the uses that you are applying them to are legal then there is not a lot that the state
can do to stop you.
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Texium
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I was thinking of trying to synthesize phthalocyanine, and I was wondering if it would be possible to bypass the step of heating the phthalic
anhydride and ammonia. I do not currently have any good, clean ammonia solution, and would prefer to not introduce the surfactanty crap that I have
into the mix. I've read in many places that phthalocyanine can be produced from heating phthalic acid, urea, and a metal salt, but there is never
anything more specific than that. If anyone knows more details about such a procedure, advice would be much appreciated.
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Crowfjord
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You are correct, I made a substituted phthalocyanine with that methodology for a research project in college. It also involves molybdenum catalyst.
See:
Achar, B.N. (01/1987). "Synthesis and structural studies of metal(II) 4,9,16,23-phthalocyanine tetraamines". Polyhedron (0277-5387), 6 (6), p. 1463.
DOI: 10.1016/S0277-5387(00)80910-9
or US Patent4499260
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