NotANumber
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Photographic Chemistry Madness
Heyo! I'm a home photochemist ;*
I'm working on a lot of stuff, including my own silver photosensitive emulsion, but for now I'm willing to offer my help to anyone new to the field,
especially with chemical bath recipes ~anything from partially or fully dissolving individual color layers in color film to dyeing photographic prints
and lifting the emulsion from a broken glass plate~ and some general tips, especially since I specialize in old, expired film,,
Feel free to ask me anything! 
[Edited on 2-20-2025 by Texium]
mrrp!~
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Texium
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Welcome! I just made a minor change to the title of your thread for clarity, since "photochemistry" more typically refers to using light-promoted
reactions in synthesis, rather than the direct application to photographic development. Always great to see how amateur chemistry overlaps with other
hobbies.
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NotANumber
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Awh thank you, sorry for the mistake ":)
[Edited on 21-2-2025 by NotANumber]
mrrp!~
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j_sum1
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Nice topic. Somehow overlooked in this era of digital photography. People forget just how clever photographic chemistry is.
There was an Aussie member (no longer active) who posted some interesting stuff on cyanotypes a while back and had some really interesting examples of
his work -- using gallic acid in the process. He was kind enough to send me some of his chems. I still have some half finished projects as a result.
I should get back to it. (But it won't happen this weekend.)
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woelen
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I also have done photography, combined with chemistry. On my website, there is some info on toning and developers. The toning part may be interesting
for you. I also developed a yellow and green toner, based on vanadium, using the easy to obtain potteries V2O5.
https://woelen.homescience.net/science/photo/toners/index.ht...
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NotANumber
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Ooh interesting, though you forgot to mention lead nitrate and organic dye based toners, as it's pretty easy to substitute silver for dyes like
malachite green and many others ^.^
mrrp!~
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NotANumber
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Quote: Originally posted by j_sum1  | Nice topic. Somehow overlooked in this era of digital photography. People forget just how clever photographic chemistry is.
There was an Aussie member (no longer active) who posted some interesting stuff on cyanotypes a while back and had some really interesting examples of
his work -- using gallic acid in the process. He was kind enough to send me some of his chems. I still have some half finished projects as a result.
I should get back to it. (But it won't happen this weekend.) |
Cyanotyping is a really interesting art tbh, though I'm wondering if it'd be hard to set it in an emulsion and maybe sensitize with sulfur
nanoparticles in order to lower the energy absorption threshold like it's done with silver halide based chem. If not then perhaps a tiny amount of
silver iodide could be used as a primitive dye coupler..
mrrp!~
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NotANumber
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Phenosafranine synthesis and desensitization of panchromatic film
Heya! Below this message I attached an image of a ~probably correct~ synthesis of probably the simplest to make photographic desensitizer. As you can
see, most of the path is just making 4-phenylenediamine which is a developer, so if you have it on hand feel free to go ahead with it.
Desensitification can be achieved with concentrations as low as 0.005%, so you don't need much, and it can be used as a prewash or in the developer
itself. As for the effects, it allows you to work on panchromatic emulsions on film and glass under normal darkroom light, so it can come pretty handy
when you were shooting by feel ;)
mrrp!~
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chempyre235
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Looks like a straightforward synthesis. For academic purposes, do you know how the o- and p- nitroacetanilides are separated, @NotANumber? It seems
like this could present some problems, though I don't have experience with this.
I thought of a possible route to p-phenylenediamine with terephthalic acid (from PET plastic) as the starting material:
- Neutralization to the ammonium salt;
- thermolysis to the amide;
- Hoffmann rearrangement to the diamine. (Can NaOCl be used?)
I'd certainly like to know some thoughts of more experienced chemists on the viability and issues with this route.
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NotANumber
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| Quote: Originally posted by chempyre235 | Looks like a straightforward synthesis. For academic purposes, do you know how the o- and p- nitroacetanilides are separated, @NotANumber? It seems
like this could present some problems, though I don't have experience with this.
I thought of a possible route to p-phenylenediamine with terephthalic acid (from PET plastic) as the starting material:
- Neutralization to the ammonium salt;
- thermolysis to the amide;
- Hoffmann rearrangement to the diamine. (Can NaOCl be used?)
I'd certainly like to know some thoughts of more experienced chemists on the viability and issues with this route. |
They're separated pretty easily as o-nitroacetanilide is insoluble in alcohol :]
I took some time to write down the entire procedure, the second paragraph is theoretical for now, the first one is from two procedures given by Vogel
mrrp!~
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wg48temp9
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| Quote: Originally posted by NotANumber | Heya! Below this message I attached an image of a ~probably correct~ synthesis of probably the simplest to make photographic desensitizer. As you can
see, most of the path is just making 4-phenylenediamine which is a developer, so if you have it on hand feel free to go ahead with it.
Desensitification can be achieved with concentrations as low as 0.005%, so you don't need much, and it can be used as a prewash or in the developer
itself. As for the effects, it allows you to work on panchromatic emulsions on film and glass under normal darkroom light, so it can come pretty handy
when you were shooting by feel  |
I was intrigued by that synthesis of your desensitizer (phenosafranine). I am familiar with the synthesis of poly-aniline and poly-phenylendiamine (p
or o) using ammonium persulphate as the oxidant.
I found a paper that describes the synthesis mechanism of phenosafranine, with details of the synthesis procedure. It uses ferricyanide as the
oxidant.
Perhaps by incorporating some phenosafranine units in poly-phenylendiamine it would improve its solubility.
Attachment: corbett2008.pdf (663kB)
This file has been downloaded 30 times
[Edited on 3/1/2025 by wg48temp9]
[Edited on 3/2/2025 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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Texium
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It's unclear to me how you are planning to get from the 4-nitroacetanilide to p-phenylenediamine. In your drawn out plan, you show 4-nitroacetanilide
being reduced with iron to 4-amino-N-ethylaniline, then reacting that with water to yield p-phenylenediamine. Neither of those reactions should
happen.
Iron reduction of 4-nitroacetanilide should yield 4-aminoacetanilide. The amide will not be reduced. And the reduction may take more than an hour, as
those heterogeneous metal reactions can vary in rate depending on the quality and surface area of your metal. It would be best to follow by TLC to
determine when the reaction is complete, rather than assuming it's done after an hour. From there, you should be able to hydrolyze the amide by
refluxing in aqueous HCl.
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NotANumber
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| Quote: Originally posted by Texium | It's unclear to me how you are planning to get from the 4-nitroacetanilide to p-phenylenediamine. In your drawn out plan, you show 4-nitroacetanilide
being reduced with iron to 4-amino-N-ethylaniline, then reacting that with water to yield p-phenylenediamine. Neither of those reactions should
happen.
Iron reduction of 4-nitroacetanilide should yield 4-aminoacetanilide. The amide will not be reduced. And the reduction may take more than an hour, as
those heterogeneous metal reactions can vary in rate depending on the quality and surface area of your metal. It would be best to follow by TLC to
determine when the reaction is complete, rather than assuming it's done after an hour. From there, you should be able to hydrolyze the amide by
refluxing in aqueous HCl. |
Thank you a lot for the input. I'm still a beginner and to be honest access to proper chemical education isn't too easy, so mainly I'm scrambling for
pieces of information I can find on the internet or on my bookshelf. The procedure of making 4-phenylenediamine from 4-nitroacetanilide was merely
mentioned by Vogel so I tried to find what I could. None of the sources I found mentioned reaction times so I came up with an estimate I could extend
as I go. Unfortunately I don't have access to TLC plates, being pretty much jobless so I'd have to come up with something else to track the reaction,
probably taking a sample and using a biurette to test for amine groups. As for the hydrolysys my teachers in the past decided to completely skip the
topic and any of the books I have merely mentioned it as reacting a substance with water, and not having anyone to ask I took it at face value. Also I
forgot to draw one oxygen, my bad, I was drawing it out at 5am :c
mrrp!~
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Texium
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No problem! To follow the nitro reduction, if you're going to do a qualitative test, testing for the presence of the nitro compound would be better
than testing for the amine. If you test for the amine, a positive test will not tell you whether the reaction is complete or only partially complete.
A negative result for nitro will confirm that the reaction is finished.
Here is a test procedure for nitro compounds that uses readily available chemicals: https://doi.org/10.1021/ac50111a024
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pneumatician
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I read this in pop-sci and I haven't found any more information about this developer, does anyone know anything?
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