I note that none of the suppliers carry Chlorquinol (Chlorhydro- quinone). Does anyone know how to make it? I'm guessing it is made from hydroquinone. Lootens gives a formula for a developer "for producing brownish prints by direct development" that uses it.

-- Ed Buffaloe (edb@unblinkingeye.com), January 02, 2002

Answers

Sigma-Aldrich, a major supplier for laboratory chemicals (for professional & University labs) list Chlorohydroquinone (2-Chloro-1,4- dihydroxybenzene) in its catalogue. It's not expensive (100 grams around $25-30) and there's no indication that it is especially toxic or hazardous. So it should be available from different suppliers, at least on special order.

Regards Georg

-- Georg Kern (georg.kern@uibk.ac.at), January 03, 2002.

There are other paper developers for a brown tone containing Hydroquinone and/or Glycin.

-- Patric (jenspatric@mail.bip.net), January 03, 2002.

Hi Ed.
I think you'd need a chemistry set that LaRoche would be proud of, to reliably produce Chlorquinol from Hydroquinone.
On paper, it doesn't look too difficult. Just the addition of a Chlorine radical in the ortho position on the Benzene ring.
That might be achieved by passing Chlorine gas over Hydroquinone, and then neutralising the Hydrochloric acid that would be formed, or electrolysising a solution of common salt and Hydroquinone, and neutralising the Sodium Hydroxide(?) bi-product. The real difficulty, I imagine, comes in preventing the formation of products like 2:5 dichloro - dihydroxy benzene (which is also a developer, but a very active one that's prone to fog formation), or of simply displacing Hydroquinone's Hydroxyl radicals by Chlorine. This would form para-dichlorobenzene, which has no developing ability as far as I know.
I can't vouch that any of the above methods would work at all, really. My knowledge of organic chemistry only extends to photographic applications, and perhaps there's any easy and reliable way to do it.

Have you tried the addition of Ammonium Chloride to an M-Q or Hydroquinone developer, as suggested on the forum a few weeks ago? That gives a very warm-toned result.
Maybe Chlorquinol is even one of the byproducts formed, along with an aminophenol of some sort.

-- Pete Andrews (p.l.andrews@bham.ac.uk), January 04, 2002.

Brown Tone Paper Developer Agfa 120

Stock Solution

Warm Water (125 F or 52 C) - 750.0 ml

Sodium Sulfite, desiccated - 60.0 grams

Hydroquinone - 24.0 grams

Potassium Carbonate - 80.0 grams

Add cold water to make - 1.0 liter

This developer will produce a variety of brown to warm black tones on various papers depending on dilution and exposure time. The following table lists the dilution and exposure for various tones on Agfa papers.

Development Conditions for Agfa Developer 120 Development Paper Type: Brovira Image Tone: warm black Exposure Time: normal* Dilution: 1:5 Development time @ 68 deg F (20 C): 4-5 minutes Paper Type: Portriga Rapid Image Tone: brown-black Exposure Time: 1 « x longer than normal* Dilution: 1:4 Development time @ 68 deg F (20 C): 3 minutes

*By normal exposure is to be understood the exposure required to produce the best possible print when developed for 1 « minutes in Agfa 100.

Brown Tone Paper Developer Agfa 123 For Portrait Paper Stock Solution

Warm Water (125 F or 52 C) - 750.0 ml

Sodium Sulfite, desiccated - 60.0 grams

Hydroquinone - 24.0 grams

Potassium Carbonate - 80.0 grams

Potassium Bromide - 25.0 grams

Add cold water to make - 1.0 liter

This developer produces tones ranging from brown black to olive brown on Portriga Rapid paper depending on dilution and exposure. The table below gives the typical development conditions for the various tones.

Development Conditions for Agfa Developer 123 Paper Type: Portriga Rapid Image Tone: brown-black Exposure Time: 2 « x longer than normal* Dilution: 1:1 Development time @ 68 deg F (20 C): 2 minutes Paper Type: Portriga Rapid Image Tone: neutral to sepia brown Exposure Time: 2 x longer than normal* Dilution: 1:4 Development time @ 68 deg F (20 C): 5-6 minutes The term "normal exposure" means the exposure required to produce the best possible print when developed for 1-1/2 minutes in Agfa 100.

Paper Developer Agfa 124 for olive-brown tones

0,8g Metol

4g hydroquinone

15g sodium sulfite

9g sodium carbonate

8g potassium bromide

Exp. times and development times 2x

-- Patric (jenspatric@mail.bip.net), January 04, 2002.