[pure-silver] Re: Hydroquinone - would you like fries with that?
- From: Gerald Koch <gerald.koch@xxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Mon, 2 May 2011 21:45:40 -0700 (PDT)
It is the ortho and para positions that are usually photographically active.
This is systematised by the Kendall - Pelz Rule. For example, hydroquinone and
catechol are developing agents while resorcinol has little or no activity.
________________________________
From: Richard Knoppow <dickburk@xxxxxxxxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Sent: Mon, May 2, 2011 9:37:37 PM
Subject: [pure-silver] Re: Hydroquinone - would you like fries with that?
----- Original Message ----- From: "Jim Brick" <jim@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, May 02, 2011 8:45 AM
Subject: [pure-silver] Re: Hydroquinone - would you like fries with that?
You are correct (as usual) Richard, Metol is used with OPD thus putting OPD in
the role of a solvent, even though these formulas usually use a large amount of
sodium sulfite (?). Some references list OPD as a reducing agent but I suspect
that if it exhibits this trait, it is only in combination with other chemicals,
such as Metol. Not remotely being an expert, I just repeat what I read and what
you (Richard) write... :-)
Jim Brick
Sunnyvale, CA
http://www.photomojo.org/vip.swf
The three forms are ortho, meta, and para. This describes where the amino
groups are attached to the benzine ring of the compound. My mememory is that
both para and meta can be active reducing agents but not ortho. I think this is
true of all hetrocyclic benzine compounds.
--
Richard Knoppow
Los Angeles
WB6KBL
dickburk@xxxxxxxxxxxxx
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