Chlorhydroquinone

From Silvergrain Labs

Chlorhydroquinone (aka monochlorhydroquinone or chlorohydroquinone) is a substituted hydroquinone where one place on the benzene ring is substituted with chlorine. It is a good developing agent, which appears in formulae of historical interest, and the agent was traded with name Adurol. This name was also used for bromhydroquinone. These halogen substituted hydroquinone were sometimes used in warmtone print developers.

The effect of chlorhydroquinone can be closely mimicked by MQ or other developer combination when the developer concentration and pH are suitably adjusted.

Although I don't claim there is any magical effect that can be obtained from chlorhydroquinone, synthesis of this compound is rather straightforward. One way to do this is to react hydroquinone with sulfuryl chloride (SO2Cl2) in a suitable organic solvent, such as ethyl acetate or glacial acetic acid (US Patents 4439595 and 4439596 assigned to E.I. du Pont de Nemours)

French Patent 2574785 assigned to Rhône-Poulenc discloses yet another method using HCl and H2O2 in place of sulfuryl chloride.

Another known approach is to begin with p-benzoquinone.