Synthesis of Rodinal Substitute (looking for help with the chemistry)

[hol571]

I'm looking for a little help with the synthesis of a Rodinal substitute. All chemicals I'm using are either from Sigma-Aldrich or Acros Organics, so I don't think that is a problem.

The synthesis of a Pararodinal acetaminophen based formula (tubes 1-2) is straight forward and produces the straw color of commercially available Rodinal. It also develops (1:25 dilution) a test piece of light exposed film without issue (TriX or HP5)

However, when attempting to use the 4-aminophenol base (aka para-aminophenol) (tubes 3-6), I get a dark purple colored solution. Also, I couldn't get close the amount of potassium sulfite in solution that the starting recipe had.

For those of you that have tried this, is it normal? If not, will you point me in the direction of what went wrong?

Thanks!

Recipes used listed below, and all tubes have been sitting for 2 weeks

Images to reference
Tubes 1-6 (left to right)

Tubes 2-6 (left to right)

Pararodinal Recipe (digitaltruth.com):
15g acetaminophen
50g sodium sulfite (Na2SO3)
20g sodium hydroxide (NaOH)

Scaled for 50mL
used pure acetaminophen, no tablets or capsules

tube 1 - pararodinal
3g acetaminophen, 10g, Na2SO3, 4g NaOH, 50mL dH2O
I didn't fully dissolve the sodium sulfite first
brown precipitate (ppt)

tube 2 - K-pararodinal (same molar equivalent of SO3- and OH- as original formula)
replaced NaOH with KOH, Na2SO3 with K2S2O5 (potassium metabisulfite)
3g acetaminophen, 8.89g, K2S2O5, 10.1g KOH, 50mL dH2O
no ppt

10g NaSO3 = 0.08mol
4g NaOH = 0.1mol
3g acetaminophen = 0.02mol
so 0.1mol KOH = 5.61g
0.08mol K2SO3 = 12.66g
using K2S2O5 + 2KOH --> 2K2SO3 + H2O
you need 0.04mol K2S2O5 = 8.89g
plus 0.08mol KOH = 4.49g
therefore total KOH is 4.49g+5.61g = 10.1g

----------------------------------------------------------------------------
From APUG modern rodinal substitute resources page

starting points for tubes 3-5
Rodinal Substitute
p-Aminophenol.(free base) ................... 41 g
Potassium sulphite (anh) ..................... 348 g (I can't get anywhere close to this into solution)
Potassium Hydroxide ........................... 27 g
Potassium Bromide ............................. 10 g
Benzotriazole 1% ............................... 10 ml
Water to make .................................. 1 litre.
If necessary adjust to pH 14

starting point for tube 6
EZ-Rodinal
To 400 ml water, add:
Sodium sulfite (anhyd) 85 g
p-Aminophenol base 40 g
Stir well. Add
Sodium hydroxide 13.8 g or Potassium hydroxide 19.2 g
Add water to make 500 ml.

--------------------------------------------------------------------------

chemicals:
distilled water
4-aminophenol base (sigma >99%, CAS 123-30-8)
Potassium Sulfite (acros >90%, CAS 10117-38-1)
Potassium Metabisulfite (sigma >98%, CAS 16731-55-8)
Potassium Hydroxide (sigma >85%, CAS 1310-58-3)
Potassium Bromide (sigma >99%, CAS 7758-02-3

scaled for 50mL

Tube 3: (2.05g 4-amino, 17.4g potassium sulfite, 1.35g KOH, 500mg KBr, 500ul 1%benzo)
Potassium sulfite would not fully dissolve, even at 100C (could only get ~10g into 50mL solution)
added in following order 25mL H2O+ Ksulfite + 4 amino +KOH, bring to 50mL. purple color
added an excess of KOH, turned pinkish in color
brown ppt

Tube 4: same as tube 3, order of addition changed
mix 10mL H2O + 4-amino + KOH in separate tube (dark purple color)
add to H2O+ sulfite mixture (still not fully dissolved, bring to 50mL. purple color.
added excess KOH, slowly turning brownish purple
brown ppt

Tube 5: reduced potassium sulfite to 4.27g, same order of addition as tube 3
(2.05g 4-amino, 4.27g pot sulfite, 1.35g KOH, 500mg KBr, 500ul 1%benzo)
no ppt

Tube 6: converted EZ-Rodinal from Na to K and used metabisulfite (molar equivalent of sulfite used is the same as EZ-Rodinal formula)
increased 4-amino, used metabisulfite
(4g 4-amino, 7.51g potassium metabisulfite, 5.71g KOH, 500mg KBr, 500ul 1%benzo)
whitish crystalline ppt

 

[Photo Engineer]

See here: http://stores.photoformulary.com/n-p/?sort=featured&page=2

Potassium Sulfite will not dissolve at much above 45g / 100 g of solution. If it will not make a 45% solution, then it has probably oxidized to the Sulfate salt and will be rather ineffective in your developer

PE

 

[Patrick Robert James]

I can't comment on all the chemistry you have going on above, but I have been using EZ Rodinal for a few years now, several batches, and it has worked really well for me. I use Sulfite from a pool supplier and Hydroxide from the hardware store.....

I should add that when I mix it, it is a straw color and it gradually darkens over time.

 

[Gerald C Koch]

There are probably dozens of recipes for Rodinal all claiming to be the real mccoy. There is only one that we know for certain.

Agfa Rodinal (Wolfen Recipe)

This is the formula which was collected from the Agfa Wolfen plant in 1945.

Distilled water ………………………………………………………………… 340 l
Paraminophenol …………………………………………………………………… 34 kg
Potassium sulfite, 30% w/w at 55°C ……………… 558 kg
Potassium hydroxide, 34% w/w………………………………… 50 kg
Potassium bromide* ………………………………………………………… 5.52 kg
Agfa P.1347 antifoggant …………………………………………… 42 g

* The potassium bromide should first be dissolved in a small amount of water.

Dissolve 34 kg of para-aminophenol in 340 litres of water. Add 558 kg of a 30% solution of potassium sulphite
at 55C followed by 50 kg of a 34% potassium hydroxide solution, then 5.52 kg of potassium bromide in a little
water. Add 42 g P.1347 (an Agfa-specific anti-foggant). Filter and allow to stand for 14 days.

 

[NedL]

wow you could develop a lot of film in that!

 

[Rudeofus]

I have made a similar observation with Potassium Sulfite: Since it is outrageously expensive when sourced from the usual suspects here in Europe, I tried to make it myself from Potassium Metabisulfite and Potassium Hydroxide. While 45% Potassium Sulfite solution used to be commercially available, my bottle with self mixed Potassium Sulfite has strong precipitate on the bottom. I like PE's explanation with Potassium Sulfate, it's indeed a lot less soluble than Potassium Sulfite.

Raw compound purity may also be an explanation for your trouble with Rodinal made from p-Aminophenol: Acetaminophen may be available in much purer form because it has medical uses.

 

[Alan Johnson]

(there was a url link here which no longer exists)
I found it more convenient to use the bisulfite, have had no problems with this,it remains clear.

 

[Harry Stevens]

Just made another 500ml and 250ml bottle up yesterday because I have ten rolls of 200 asa Fomapan 120 coming, the stuff I makes seems to last forever.

sodium Metabisulfite ,sodium Hydroxide, and paracetamol tablets simply because all cheap and available to me.I have potassium bromide but I have never put it in the mix.

Just to add I know diddly-squat about chemistry.

 

[removed account4]

there was an appugger here a few years ago who
had a different recipe for rodinal, and he suggested
you need to use extreme heat to combine some of the ingredients
i don't remember the guy's name, his avatar ken or something
his avatar was a monkey wearing glasses i think. maybe his
old posts canhelp you
good luck

 

[Rudeofus]

John, are you sure this was about Rodinal and not some Phenidone+Ascorbate in TEA type concentrate? Since Rodinal is water based and extremely alkaline, I'm not sure whether heating this up to high temperatures would be a good idea ...

 

[removed account4]

John, are you sure this was about Rodinal and not some Phenidone+Ascorbate in TEA type concentrate? Since Rodinal is water based and extremely alkaline, I'm not sure whether heating this up to high temperatures would be a good idea ...

hi rudeofus

i just learned ( again ) about the person who i was thinking of ..
it turns out this guy wrote a lot of things that might not have been true and maybe
what i just posted was one of them, or it involved another developer ( panthermic 777? )

so please disregard this previous comment i made

turns out there is a chance it might not be true !

sorry for my confusion
john

 

[Gerald C Koch]

Since sodium salts are usually less soluble than their potassium analogues you will have trouble mixing anything resembling Rodinal using them. In addition the potassium salts are more active in developers.

 

[hol571]

thanks for the replies

PE: I was able to get the potassium sulfite completely into a 45% w/w solution this time with heat and sonication; however, as it cooled back to RT some material precipitated out. I'm guessing this is the sulfate contamination? Filtering it away shouldn't be a problem right? fyi this is the material I'm using: http://www.acros.com/DesktopModules/Acros_Search_Results/Acros_Search_Results.aspx?search_type=CatalogSearch&SearchString=potassium%20sulfite

The metabisulfite + extra KOH to convert it to sulfite is definitely goes into solution much easier

I'm still a little confused why I get the purple color upon the reaction of the 4-aminophenol + KOH? I know my 4-aminophenol is clean, I'm using >99% HPLC grade from sigma-aldrich, which I also use in my job (it's a standard used along with acetaminophen for glutathione trapping of reactive metabolites in drug metabolism and distribution studies by mass spectrometry)

Gerald: thanks for the formula, I'll scale it down and give it a try

 

[Harry Stevens]

John, are you sure this was about Rodinal and not some Phenidone+Ascorbate in TEA type concentrate? Since Rodinal is water based and extremely alkaline, I'm not sure whether heating this up to high temperatures would be a good idea ...

I warm up to the individual paracetamol and sodium Metabisulfite to near boiling and then I mix the sodium hydroxide when the individual chemical mixes are luke warm I then mix them all together in what I I consider the right order. I still get the crud at the bottom but it is a big improvement. Works great for me.
I remember other posters who have had other developers that have crystallized at the bottom and they have been recommender to heat them up to be able to use them again .

 

[Gerald C Koch]

I have made rordinal several times from the recipe in the Morgan & Morgan Darkroom Guide. It is perfectly normal for the resulting developer to be a lavender or purple color.

 

[Photo Engineer]

Anything that does not dissolve at room temperature at 45% K2SO3, is probably K2SO4.

PE

 

[sfaber17]

Since sodium salts are usually less soluble than their potassium analogues ..

I always thought that generally sodium salts were more soluble than potassium ones because of chlorate and perchlorate for example. Is it peculiar to sulfite or still true in general?

 

[Photo Engineer]

True in general.

PE

 

[Gerald C Koch]

It all has to do with the relative sizes of the sodium and potassium ions. Another factor is just how much of the negative nuclear charge is seen by a valence shell electron. The presence of an extra electron shell in potassium ions reduces the nucleus electron attraction. All in all increased solubility with potassium salts over sodium ones. That is why Agfa chose using concentrated solutions of potassium hydroxide and sulfite over sodium solutions. Less shipping cost.

https://www.quora.com/Are-potassium-salts-usually-more-soluble-than-the-equivalent-sodium-salts

 

[Photo Engineer]

One must be careful that little or no Potassium is carried over to the fix. Literature suggests that this ion can poison (slow down or stop) fixing action.

PE

 

[hol571]

Gerald: Thanks for letting me know that the purple is normal. I scaled down the recipe you provided omitting the agfa antifoggant. I couldn't get all the 4-aminophenol into water (even with heat), but proceeded anyway, hot filtering the solution after everything was added. Interestingly, the solution is still tan colored this morning, but has developed large crystal shards overnight. My previous solutions only have a fine ppt in them.

PE: interesting point about the potassium salts affecting the fixer, I'd like to learn more about it. Will you recommend some resources I should look at?

 

[Photo Engineer]

Books by Haist and Mees and James both mention this. I believe but am not sure that Anchell and Troop also mention it.

PE

 

[Rudeofus]

Re: potassium ions in fixer: it appears to be a common theme in American literature, whereas German industry seems to have a lot less issue with it (c.f. Agfa 304 recipe and others). During my investigations into this I discovered, that Potassium ion is smaller than Sodium ion when both are fully hydrated, therefore Potassium ion diffuses faster through gelatin. Indeed, one can speed up a Sodium Thiosulfate fixer with Potassium Acetate! The effect is much more limited than what we see with Ammonium Acetate, though.

Another issue are mixed salts between Sodium, Potassium, Silver, Iodide and Thiosulfate: some of them are sparingly soluble, and may well explain premature fixer exhaustion when fixing high-iodide emulsions. If this effects is more prone to happen with Potassium ions, then this would explain Kodak's dislike to Potassium in fixer. Note that all this is based on assumptions, not hard evidence or experimental data, so YMMV.

 

[Ian Grant]

Just to clarify, Potassium carry over will have no ill effects on Fixer, the amount needed in carry over would have already caused the fixer to collapse due to the other chemicals carried over from the developer. A good stop bath (or water rinse with films) protects the fixer in many ways.

All the major companies that includes Ilford, Kodak, Agfa, have used (some still do) Potassium Alum as a hardener in fixers with no issues and at levels way more than would be possible with carry over. In addition many commercial liquid print and some film developers use Potassium Carbonate and Potassium (or Sodium) Hydroxide.

This thread is about Rodinal and it's used dilute there would be zero problem of Potassium carry over, sometimes there's a need for a reality check on this Forum .

Ian

 

[Rudeofus]

Film and paper emulsion composition has changed quite a bit during the last couple of decades, especially film emulsions are quite high in iodide these days. If there is a disadvantageous interaction between silver, iodide, potassium and thiosulfate, which does not exist with sodium or ammonium, then Kodak's assertion "Potassium can poison fixer" may hold, even if older publications see no issue with Potassium in fixer.