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Author: Subject: Phthalic acid synthesis
teodor
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[*] posted on 2-12-2024 at 02:02


I remeber one more point why I don't like permanganate. When its reduction is started it doesn't depend on the rate of your organic product oxidation. It just don't stop untill all permanganate is reduced (not because of the organic oxidation). I believe with CrO3 you can see the actual rate of your compound oxidation (the change of the color).
You can easily get any (di) chromate from CrO3 in situ, but CrO3 is not always a substitution for dichromate for acetic acid solvent because it doesn't dissolve in AcOH as good as dichromate. So you have to mix NaOH with it in a small quantity of water before AcOH addition in this case.

[Edited on 2-12-2024 by teodor]
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[*] posted on 2-12-2024 at 22:53


I have no personal grudge with permanganate. Is just that it is difficult to source because it’s listed as a drug precursor over here in the EU. So you have to make it yourself from manganese oxide by the fusion process, which takes time.



[Edited on 3-12-2024 by Keras]
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[*] posted on 2-12-2024 at 23:20


Quote: Originally posted by Keras  
I have no personal grudge with permanganate. Is just that it is difficult to source because it’s listed as a drug precursor over here in the EU. So you have to make it yourself from manganese oxide by the fusion process, which takes time.


In the UK it is sold on eBay, Amazon, APC Pure and several other sites.




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[*] posted on 3-12-2024 at 00:51


Quote: Originally posted by Keras  
I have no personal grudge with permanganate. Is just that it is difficult to source because it’s listed as a drug precursor over here in the EU. So you have to make it yourself from manganese oxide by the fusion process, which takes time.
[Edited on 3-12-2024 by Keras]


But you need it in the form of solution. So, you can try to use manganese sulfate + ammonium persulfate (as you planned) + silver nitrate to generate it in situ during the synthesis.
Check this thread: https://www.sciencemadness.org/talk/viewthread.php?tid=15996...

Because the synthesis will consume the permanganate there is a chance it will go to completion.
Also the rate of permanganate generation can change the synthesis, but probably it would be interesting to try. As I said, the problem with permanganate is that it can be reduced faster than the organic compound to be oxidised.
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[*] posted on 3-12-2024 at 12:13


Lol, turns out I might’ve made manganese sulphate inadvertently. During my last experiment with naphthalene and potassium permanganate, I collected the cake obtained after reaction and filtration, which contains mainly manganese oxide, and added in it sodium hydrosulphite. It immediately cleared up and I’m now with a beaker full of a whitish powder in water. That might be it. I’ll filter it tomorrow and see.
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[*] posted on 8-12-2024 at 08:32


While this isn’t exactly in the spirit of the thread, why don’t you just buy phthalic anhydride from a chemical supplier? S3 Chemicals has 500 g for 27 €. That seems very reasonable as you would need kilos of permanganate and a bucket scale setup to make that much.



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[*] posted on 8-12-2024 at 09:00


Quote: Originally posted by Texium  
While this isn’t exactly in the spirit of the thread, why don’t you just buy phthalic anhydride from a chemical supplier? S3 Chemicals has 500 g for 27 €. That seems very reasonable as you would need kilos of permanganate and a bucket scale setup to make that much.


Might be a good idea. It’s 57 € here which, for a commodity chemical produced at multi-ton scale, always seemed to me excessive.
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[*] posted on 8-12-2024 at 11:22


Yeah, that is a little steep. Commodity chemical or not, selling it packaged as a lab reagent with a guaranteed level of purity will inevitably result in a markup. S3’s price at least seems reasonable in that context. I’m selling phthalic anhydride from Aldrich 500 g for $25, but the shipping to Europe would almost certainly make it a worse deal.



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[*] posted on 10-12-2024 at 23:02


Which country is Laboratorium Discounter based in? There web site is a bit obscure.
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[*] posted on 12-12-2024 at 00:39


Quote: Originally posted by Boffis  
Which country is Laboratorium Discounter based in? There web site is a bit obscure.


The Netherlands. But it is not the seller I can recommend, we have a separate thread where some people already shared their negative experience with them.
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[*] posted on 12-12-2024 at 01:21


Last week I again ordered some chemicals from Laboratoriumdiscounter. I ordered a small amount of 98% hydrazine hydrate and sodium peroxodisulfate from them. I received the chemicals a few days later. My experiences with this company are quite good, but indeed, sometimes things go less smooth. My previous order took several weeks, because their supplier took a long time to deliver the chemical to them. In my experience, it is more a matter of communication (or the lack of communication) than wrong intent. I already told them this and wrote that on a review site (Trustpilot) as well.



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[*] posted on 12-12-2024 at 06:54


Quote: Originally posted by woelen  
Last week I again ordered some chemicals from Laboratoriumdiscounter. I ordered a small amount of 98% hydrazine hydrate and sodium peroxodisulfate from them. I received the chemicals a few days later. My experiences with this company are quite good, but indeed, sometimes things go less smooth. My previous order took several weeks, because their supplier took a long time to deliver the chemical to them. In my experience, it is more a matter of communication (or the lack of communication) than wrong intent. I already told them this and wrote that on a review site (Trustpilot) as well.


I really appretiate your effort to provide the constructive feedback for them. I am really glad if they are going to improve their way of business and are reading the feedbacks for that purpose. Yes, I know that they probably have no bad intentions, but at the present time this seller is the last one I can even consider when buying chemicals and glassware. As for the component in question I would better by some phthalic anhydride from S3.

The day before yesterday I've ordered potassium and ammonium persulfate from labshop.nl as well as some laboratory consumables. Yesterday it was delivered exceptionally well packed. So, I am not always prefer german companies, you see.

[Edited on 12-12-2024 by teodor]
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[*] posted on 12-12-2024 at 07:22


Quote: Originally posted by teodor  
Quote: Originally posted by woelen  




I really appretiate your effort to provide the constructive feedback for them.


I’m used to ordering many items from LD and, yes, they are a bit messy, but I suppose this is just the result of their supply chain being unreliable. Last time I enquired about a late delivery, they told me they weren't surprised the supplier they had to source the item from was late, it was apparently usual. Then they did go great length to assuage this, they sent my items on the fly as they received it, which ended up meaning three parcels instead of just one (and I paid no extra fees, they assumed the extra two shippings cost).


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[*] posted on 10-1-2025 at 05:55


So I tried the oxidation of naphthalene (1.3 g, 10 mmol) dissolved in 20 mL of glacial acetic acid by 6.5 g (~ 40 mmol) of potassium permanganate.

The reaction is weird. The permanganate will turn to manganese dioxide quite calmly, until there is a sudden bubbling and the temperature suddenly rises.

I was caught off guard the first time, and some of it spilled out of the beaker.

I redid it, enclosing the beaker in a bigger beaker, and filling that bigger beaker with ~10°C water. Same phenomenon, repeated twice, but this time under control, so nothing bad happened. It subsides quite quickly.

Problem: at the end I’m left with a goo/jelly of manganese dioxide mixed with acetic acid I don’t really know what to do with. I tried to filter it, but apart from messing up my Hirsh funnel, which took ½ hour to clean up afterwards, I got nothing.

Would phthalic acid steam distillate?

I can’t extract it with base, because of acetic acid.
I can dilute it until the goo is liquid, filter out the dioxide, then distill it, or extract it using DCM?

[Edit: typos]

[Edited on 10-1-2025 by Keras]
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[*] posted on 10-1-2025 at 07:31


Quote:
Would phthalic acid steam distillate?

No. It melts at 207 °C and, for some strange reason, I can't find its boiling point. But you can distill acetic acid from the mix.

Quote:
I can dilute it until the goo is liquid, filter out the dioxide, then distill it, or extract it using DCM?

You mean diluting it with water or with acetic acid? If water, some phthalic acid will be separated along with manganese dioxide. If acetic acid, use a cotton ball tucked into the stem of the funnel.

I think that you can make ethyl esters. Diethyl phthalate boils at 278 °C, while ethyl acetate boils at 77 °C. It won't be too hard to separate them.




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[*] posted on 10-1-2025 at 08:07


I had thought about distilling (or evaporating) acetic acid, but I'd be left with a solid chunk. Maybe I could soak it in DCM to extract the phthalic acid, decant, filter and evaporate.

Making esters could be worth it, but really I don’t want to go the extra mile for a gram or two of product.
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[*] posted on 10-1-2025 at 08:09


Quote: Originally posted by bnull  

No. It melts at 207 °C and, for some strange reason, I can't find its boiling point. But you can distill acetic acid from the mix.

Above 200°C, phthalic acid decomposes to phthalic anhydride which sublimates at 295°C.




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[*] posted on 10-1-2025 at 08:39


Quote: Originally posted by Sir_Gawain  
Above 200°C, phthalic acid decomposes to phthalic anhydride which sublimates at 295°C.

Oh, that. I knew I was missing something. Thanks.




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