W665, o-phenylenediamine

Windisch developer W665 contains ortho-Phenylenediamine.
While not having so deep knowledge in chemistry I wonder
what function the o-PD has in that developer and also in
other developers in which it might be included.

Since it is an aromatic diamine it is hazardous to handle and
i wonder if it is substitutable by some other chemical that work
in a similar maner?

Does it compound with the silver and slows grain-growth?

Anyone with information and deeper knowledge about this?

Thanks in advance,

Jan Johansson

It's a developing agent. If I recall correctly, the phenylenediamines give very fine grain and low film speed. I think they used to be popular in the 1930s and 1940s, less so today due to toxicity.

I'm pretty sure that some phenylenediamine derivatives (though not necessarily the ortho compound) are used in colour developers.

Hope this helps.

I think the stronger developing agent is the p-phenylenediamine. The ortho has silver solvent capabilities with reduced developer potential. I could be wrong. It has been known to happen.

Jordan is right, but I think ALL color developers are p-phenylenediamine derivatives, nor o-phenylenediamines. Also, as a b&w developer, phenylenediamines are made obsolete partly because crystals used in b&w films are better designed for more common agents today. Many modern films have problems with phenylenediamines such as low speed, weak image contrast, and most significantly dichroic fog.

As b&w developing power, I think ortho position would make it stronger than para position.