Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: three winged hawk on June 25, 2005, 09:31:14 PM
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Today I went to my local photo supply store, hoping to find hydroquinone. Oh, indeed, it was found, but only as a part of a mixture. One canister contains and unknown ratio of hydroquinone and sodium sulfite. Another contains hydroquinone (71%) and p-methylaminophenol sulphate (28%). How could one isolate relatively pure hydroquinone from these mixtures?
hydroquinone physical constants:
melting point: 170C
boiling point: 285C
water solubility: 7g/100g
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I always get these confused, is hydroquinone the same as benzoquinone, or is it the reduced form, p-hydroxy phenol?
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'Tis the latter, p-hydroxyphenol.
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I had to chemdraw it.
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Today I went to my local photo supply store, hoping to find hydroquinone. Oh, indeed, it was found, but only as a part of a mixture. One canister contains and unknown ratio of hydroquinone and sodium sulfite. Another contains hydroquinone (71%) and p-methylaminophenol sulphate (28%). How could one isolate relatively pure hydroquinone from these mixtures?
hydroquinone physical constants:
melting point: 170C
boiling point: 285C
water solubility: 7g/100g
Purifying it is really hard. When it is mixed with sulfite, then it forms a complex, which protects it from aerial oxidation (stabilization of the active developer, such as hydroquinone is the main reason of adding sulfite to photo-developers).
Separation of hydroquinone from metol also is hard to achieve. One way to get rid of the metol is adding the hydroquinone/metol mix to a solution of Na2SO3 in water. The hydroquinone will dissolve quickly, while the metol remains undissolved (this does not dissolve in a solution of Na2SO3). But doing this brings you back to the first mix again :(.
A good (and cheap: $10 - $15 per lb) source of pure hydroquinone is www.artcraftchemicals.com. They ship this chemical worldwide. Another source is www.jdphotochem.com. They also ship hydroquinone worldwide. I ordered from both companies and have good experience with them.
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Ah, thank ye! Those places do have the pure chemical for a great deal cheaper. Is it generally easy to recieve such a package at a private residence, or are there hazardous shipping/chemical-in-the-mail laws to complicate things? thanks again
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Ah, thank ye! Those places do have the pure chemical for a great deal cheaper. Is it generally easy to recieve such a package at a private residence, or are there hazardous shipping/chemical-in-the-mail laws to complicate things? thanks again
I live in the Netherlands (Europe) and I have ordered chems from both suppliers without ANY problems. No excessive shipping costs, no hazmat fees etc. Of course, it depends on where you live. I read stories about people, living in some states of the USA, where things are more difficult, but I have good confidence that you can order most of the chemicals from the supplier's list without problem.
If you order liquids, or if you order the more dangerous chems (like mercury salts, paraformaldehyde, etc.), then things become different. But just plain salts, photo developers (like hydroquinone, metol, catechol, etc) and even some solid oxidizers are not a problem.
The two suppliers I mentioned ship to private persons (I also have no connection with a chem-related company at all), who are just hobbyists.
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Wow. That jdphotochem place states that they can provide picric acid upon request. That certainly opens up a few eyes. :o
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Wow. That jdphotochem place states that they can provide picric acid upon request. That certainly opens up a few eyes. :o
But, I'm quite sure, that if you want that, then you certainly have to be prepared to pay a huge hazmat fee (at least for me, as the stuff needs to be shipped to Europe). My statement about non-problematic shipping probably does not hold for many chems from the list, which can be obtained on request.
I must not think of having them ship a liter of bromine of trifluoroacetic acid overseas to my home ;D. Customs will not be happy with that :(.
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Dude! I found some 98% Hydroquinone on Ebay.ca! It's from Canada, though. It's under Business and Industrial > Healthcare, Lab, and Life Science > Lab Supplies.