Parodinal with potassium bisulfite

Sodium hydroxide is caustic ,hazardous:
http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/sodium_hydroxide.html

Parodinal is a homebrew developer made from Paracetamol/Tylenol (aka acetaminophen) capsule contents which are reacted with sodium hydroxide to produce p-aminophenol which is the developing agent used in proprietary formulations of this type:
http://www.digitaltruth.com/data/formula.php?FormulaID=144
Usually it contains sodium sulfite crystals, here I describe a version which does not contain crystals.

I replaced 50g sodium sulfite with potassium bisulfite and some extra sodium hydroxide which produces a mixture of potassium and sodium sulfite.
2KHSO3 + 2 NaOH -> K2SO3 + Na2SO3 + 2H2O
240.3...............80.........158.3....126.............36
47.7.................15.9.......31.4......25
The formula is then:
Water..............................................................250ml
Acetaminophen...30x500mg capsule contents.........15g
Potassium Bisulfite..............................................47.7g
Sodium Hydroxide...20g+15.9g............................35.9g

The contents of 30 acetaminophen capsules and 47.7g potassium bisulfite were weighed out and separately set aside.
35.9 g sodium hydroxide was dissolved in 200ml cold water, the temperature rose from 22C to 60C,
47.7g potassium bisulfite was added slowly, T=68C.
The contents of the 30 acetaminophen capsules was added with stirring, T=66C.
The solution was made up to 250ml and allowed to stand for 3 days at room temperature in a sealed bottle to make the developing agent.
A small amount of suspended matter was filtered off through several changes of cotton wool.

The resulting Parodinal variation is a clear solution, as it contains the same number of moles of sulfite as the original formula it should keep just as well.
I just did this as happen to have some potassium bisufite spare.The Potassium sulfite formed is very soluble.
At present there are no crystals but Parodinal may have some capacity to surprise later.
It is suggested to use as Rodinal but develop 10% longer.

That's interesting.

I always found it hard to get the sulfite into solution, until I used forum member Dorff's paRodinal spreadsheet calculator to adjust quantities to use a large proportion Sodium metabisulfite (which seems much more soluble); my paRodinal works perfectly well too, and is also very clear.

Potassium salts are frequently used to make highly concentrated developers since potassium salts have a significantly greater solubility in water. They also appear to someone more active when used in developers.

Is maintaining the temperature during mixture, critical?

baachitraka said:

Is maintaining the temperature during mixture, critical?

Click to expand...

If the ingredients are added in the order given the heat of solution and the heat of reaction naturally raise the temperature and most of the acetaminophen dissolves quite rapidly so this is the easiest way to start.I daresay the acetaminophen could be made to dissolve at lower temperatures,more slowly. with more stirring so its probably not critical ,I did not try it.

How does it this version of Parodinal keep?

About a year in a slowly emptied bottle but throw out the last 10%.

Thanks. Will mix soon since the raw chemicals are cheaper.

May I know how does it will go if I mix 1l with 4x the quantity of chemicals mentioned in the above formula?

My only completed test used 250 ml over 1 year.
I suggest decant 1L into 4 250ml bottles, the sealed bottles with no air should keep for a long time.
I don't recall this being discussed, but it seems to me that if 1L is used from one bottle of developer, it will need to be opened 4 times as many times and the volume of air admitted each time will on average be about 4 times larger, so the developer will see a lot more air to oxidize it.