The role of Dimethyl Sulfoxide in Photographic Science ))

bnxvs said:

I was able to dissolve 10g of ascorbic acid (vitamin C) in 30ml of cold DMSO. I think that it will probably be possible to dissolve the same 10g of ascorbic acid in 20ml of DMSO, but with a slight heating of the mixture. Conclusion - ascorbic acid dissolves very well in DMSO.
Added to the prepared mixture 0.25g of phenidone, dissolved separately in 1ml of DMSO (25% solution). As a result, I got a good and twice as concentrated base (about 50ml) for the preparation of ascorbate developers

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Do you plan to put an alkali into the concentrate somehow to make it a complete developer concentrate? Or add alkali to the working solution at the time of developing?

I haven't decided yet. Both approaches have their positive and negative aspects.

What's gained by this, then? Do you get to mix a tank of 250-300 ml of developer with a small enough quantity of concentrate that it's hard to measure accurately, even with a syringe?

If you are having difficulty measuring 5-10 ml of concentrate and mixing it with 250-300 ml of water - Yep, this is not your way.

I don't -- but you stated it was twice as concentrated as Gainer's glycol developer, with which I'm not familiar.

Well, in that case, maybe it makes sense for you to familiarize yourself with the original source first? And then we can discuss your arguments ... if you'll want to continue, of course ...

albada discovered that sodium metaborate dissolves in propylene glycol in this long thread:
https://www.photrio.com/forum/threads/progress-on-xtol-concentrate.92378/page-18#post-1232773
(In case it might be of interest to try it in DMSO with suitable precautions)

Alan Johnson said:

albada discovered that sodium metaborate dissolves in propylene glycol in this long thread:
https://www.photrio.com/forum/threads/progress-on-xtol-concentrate.92378/page-18#post-1232773
(In case it might be of interest to try it in DMSO with suitable precautions)

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How do you think sufficient metaborate per 10g of ascorbic acid?

https://www.photrio.com/forum/resources/mocon-xtol-quality-in-a-long-lasting-concentrate.219/
Probably an easier way to proceed would be to make a copy of Mocon, where the research has already been done, scaling up the total volume as suits your requirements.
Replace propylene glycol by dimethyl sulfoxide and adjust the pH with more/less metaborate if it will dissolve.
Be careful as metaborate can react with some substances in ways not previously known.

The question is not solved so easily. You are forget about the sulfite, that is added to the working solution. It significantly affects the final pH of the solution.
I asked about the amount of sodium metaborate precisely because I don't know the values of its pKa. I'm not so good at mathematics and chemistry as to calculate these values from NaOH and borax.
p.s. But, if you mean a two-solution developer (with separate sulfite) - OK, it's not a problem. I'll do this experiment soon.

Yes. it should be OK to use the same sulfite part B as Mocon and adjust the pH of the working solution by trial and error re the amount of metaborate in part A if it will dissolve.
IIRC it took nearly a year to get the final formula of Mocon so you have some time still to go , if DMSO version works at all.

I was able to dissolve in the previous solution about 3g of sodium metaborate (about 1g per 10ml of DMSO + ascorbic acid and phenidone). When added with water, this concentrate gives neutral pH (about 7).
After the addition 4g of sodium sulfite per 100ml in this working solution, pH becomes approximately 8.3-8.5. So, the X-ray film (Fuji HR-U) blackened in about 2 minutes. Darkening test of Tasma type 42L is also about 2 minutes. It's low active developer.
I think increasing the amount of sulfite or adding alkali to the working solution would be appropriate here.
p.s. Conclusion: As I expected, there is no feasibility in using metaborate in such a concentrate. A much more efficient starter and buffer would be TEA / DEA. Or a second solution of sodium carbonate and borax. In principle, sulfite is not required for one-time use, since it makes no sense to store such a working solution.

Leaving out a buffer borate departs from conventional practice, see post 3 by Ryuji here:
https://www.photrio.com/forum/threads/pc-sulfite-a-simple-developer-giving-xtol-quality.84781/
So your conclusion is rather disappointing. Borate is not in Xtol for the fun of it.

bnxvs said:

there is no feasibility in using metaborate in such a concentrate. A much more efficient starter and buffer would be TEA / DEA.

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Would you be adding TEA to the concentrate or directly to the working solution? If it is the former, then the advantage of a concentrate is lost as TEA will add to the volume of the concentrate. If it is the latter, then the convenience of a single part developer stock is lost.

Well, I see at least a few advantages here:
a) convenient dissolution of chemicals, without the need for heating and excessive training of hands
b) availability and low cost of solvent
c) the ability to combine various substances (for example, sulfite ions and developing agents) without the use of complex equipment
As for the dissolution of alkaline agents, these are always complicated. In addition, buffer solutions are not only prepared on a borate basis.

bnxvs said:

I was able to dissolve in the previous solution about 3g of sodium metaborate (about 1g per 10ml of DMSO + ascorbic acid and phenidone). When added with water, this concentrate gives neutral pH (about 7).
After the addition 4g of sodium sulfite per 100ml in this working solution, pH becomes approximately 8.3-8.5. So, the X-ray film (Fuji HR-U) blackened in about 2 minutes. Darkening test of Tasma type 42L is also about 2 minutes. It's low active developer.
I think increasing the amount of sulfite or adding alkali to the working solution would be appropriate here.
p.s. Conclusion: As I expected, there is no feasibility in using metaborate in such a concentrate. A much more efficient starter and buffer would be TEA / DEA. Or a second solution of sodium carbonate and borax. In principle, sulfite is not required for one-time use, since it makes no sense to store such a working solution.

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I am the inventor of Mocon, so I've been following this thread with keen interest.
The pH of Mocon's working solution is 8.1 (yours is higher). Mocon needs 45 g of sulfite per liter, about the same as your experiment. Blackening in 2 minutes is fine. Mocon requires 10-15 minutes to develop most films to a CI of 0.58. If yours is not longer, then you have a realistic developer for conventional films. Why do you think there is "no feasibility"? I suggest that you find the time needed to develop a popular film to normal contrast.
I am interested in replacing the propylene glycol (PG) in Mocon with something else, because PG adds fog to some films when used with Phenidone (but not when used with Dimezone S).
Mark Overton

Hello Mark. Thanks for your reply. I closely follow your publications and they greatly inspire me to experiment.
Of course, I will try to do sensitometric tests as soon as I have free time.
I was primarily interested in the possibility of creating a PQ concentrate. Since I, like many amateur photographers, are worried about the change in the basis of the HC-110 and the appearance of water in it. Therefore, thoughts arose about the use of DMSO in combination with a more widespread and accessible base than DEA.
So the experiment with ascorbic acid happened by accident. As a reaction to this discussion. As it turned out, this is also quite a working option. It surprised me a little (like a gift for the New Year).

I discovered this topic when on a weird chase for a better stock solution solvent. I could easily make a 30% solution of hydroquinone from DMSO, at room temp, with just simple stirring. One caution is that the powder must be added a little at a time or it will clump and become much more difficult to dissolve.

Regardless, I wanted to contribute a bit of other interesting info regarding DMSO though. I used a 10% hydroquinone in DMSO+glycol solution for creating a lith developer for the purpose of lith printing. The results were quite altered compared to using the same formula but with a 10% solution of hydroquinone in glycol. Specific formula: 30ml HQ solution (20g HQ+100ml DMSO, topped to 200ml with glycol), 25ml 10% sodium sulfite, 4ml 10% potassium bromide, 7ml 1% PEG-3350 solution, 17ml 10% sodium hydroxide, 1.2L total working solution.

Specific differences in comparison to similar things with glycol only:

* The solution seemed to discolor more quickly, but remain stable (in terms of results) longer
* The solution would become more acidic much more quickly, requiring more frequent replenishment of hydroxide.
* The solution was much more resistant to pH spikes when adding hydroxide, indicating the DMSO forming a weak buffer
* The oddity of high pH and weird control around it led to uneven development (too high of pH on some papers can result in center of print being under developed)
* Lack of pepper balling, snow balling, pepper spots, etc.
* Much more "tame" action by the developer when the infectious period began, even with a high pH the infectious development was not overly chaotic, it proceeded somewhat slowly
* The end result tended to give much more brown tones and brown blacks, as well as decreased and "tamed" contrast levels, compared to glycol reference formula

I found a very interesting paper on this topic, for those with journal access (or have heard of a certain hub) https://doi.org/10.1163/1568567042420785

Basically what the paper lays down is that hydroquinone will complex with DMSO, this is likely why it is so highly soluble in it. However, once diluted with water it seems this complex action doesn't actually matter much. But for the purposes of a lith developer, there is minimal sulfite present as the lith development effect relies on the highly reactive hydroquinone radicals to not be scavenged by sulfite. In this paper, it talks specifically about these radicals (semiquinones) and how they will react with DMSO, resulting in a proton transfer, seemingly restoring the semiquinone to hydroquinone, if I'm understanding this properly.

Quote: "The fact that quenching of hydroquinone and resorcinol radical cation by electron transfer in DMSO was not observed could be due to the elongation of the bond length of O H in hydroquinone–DMSO, tert-butyl hydroquinone–DMSO and resorcinol– DMSO complexes. Hence, the oxidation of hydroquinone, tert-butyl hydroquinone and resorcinol in the presence of DMSO leads to a proton transfer from the radical cation to DMSO. As proton transfer was observed at very low concentration, it can be inferred that it occurs at almost diffusion controlled rate without any barrier."

Similar action is reported to happen to some extent with catechol (in other sources) which is maybe a lot more interesting to the people messing with staining developers. There could be some potential to use DMSO as "liquid sulfite" in terms of moderating the staining action of these developers, but I'm not typically doing much staining developer work so I'll leave that to someone else to research.

earlz Thank you. It's very interesting.

earlz said:

The results were quite altered compared to using the same formula but with a 10% solution of hydroquinone in glycol.

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So DMSO is much more than a solvent.

Raghu Kuvempunagar said:

So DMSO is much more than a solvent.

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As well as everything in this world )))

bnxvs said:

As well as everything in this world )))

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Not everything in this world is a solvent though. Anyway, if the presence of DMSO is going to alter the behaviour of a developer in significant and unknown ways, it means that tuning the DMSO based formulation to give the same result as the original developer is going to be nontrivial.

Raghu Kuvempunagar said:

Not everything in this world is a solvent though. Anyway, if the presence of DMSO is going to alter the behaviour of a developer in significant and unknown ways, it means that tuning the DMSO based formulation to give the same result as the original developer is going to be nontrivial.

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potentially, yea. I think it highly depends in formulation though. I think DMSO's properties will likely only matter for staining developers and lith developers. If there is a lot of sulfite as most developers have, then this radical scavenging property would not be obvious. I'm unsure about the ph buffering effect of it though. This may be due to the weird proton transfer happening in its scavenging of radicals and also not matter when using a reasonable amount of sulfite. There is also some literature touching on ascorbic acid radicals with this which might matter more since sulfite does not seem to scavenge those well.

Would the ascorbic acid / phenidone concentrate be useful in a quick FX55 developer (using the usual diluent as published)?

Murray Kelly said:

Would the ascorbic acid / phenidone concentrate be useful in a quick FX55 developer (using the usual diluent as published)?

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Why not? But sodium L-ascorbate has low solubility in DMSO (about 2mg per ml). https://www.selleckchem.com/datasheet/sodium-ascorbate-S424501-DataSheet.html
p.s. If you are going to prepare the original composition of FX-55, of course. https://en.wikipedia.org/wiki/FX-55_(film_developer)

Ascorbic acid is acceptable. The double buffer diluent will probably handle the acid with ease. If not then adjust as necessary.