Re: Alt-hardeners

Sorry I was forgetting about this thread... perhaps I thought no one
is interested in highly effective, nonvolatile and relatively notoxic
hardener... because it's just a hardener... right, it's boring.

From: Alberto Novo <alt-list@albertonovo.it>
Subject: Alt-hardeners (was: Help with what I believe is a hardening issue)
Date: Wed, 17 Nov 2004 08:47:22 +0100

> This seems a very interesting characteristic. What about its storage?

As far as I know with my short time experience with this compound
(2,4-dichloro-6-hydroxy-s-triazine), it keeps well.

> I have found cyanuric acid (2,4,6 trihydroxy - 1,3,5 triazine), its
> price is about 0.1 euro/g. For comparison, glutaraldehyde is
> 0.14-0.2 E/g and glyoxal is 1.6 E/g (both referred to the pure
> substance). May you share your operational details for the
> synthesis of 2,4 dichloro[...]s-triazine?

Well, I didn't explain well last time. This stuff occurs between
cyanuric acid and cyanuric chloride. Perhaps easiest is to begin with
cyanuric chloride and allow it to hydrolyze only partially in weakly
alkaline solution (loses one Cl and gets OH in place). That's what I
did last time. It's a simple one step reaction but takes some time. I
dissolve cyanuric chloride in acetone, and drop it slowly into
carbonate buffer (pH of about 7.5) while heated to 40C, with constant
stirring. When all is dissolved, give it a couple more hours of
stirring at 40C. The solution is ready to use after filtering for most
hardening purpose, but you might want to adjust the pH if your process
doesn't work well in alkaline environment (like cyanotype). This
compound has lower solubility than carbonates, so you can chill it
overnight and let the compound crystal out, if you need to purify
it. Don't hydrolyze too much, because dihydroxy counterpart is more
soluble and has less hardening effect.

Considering the amount of hardener (and other chemicals) I use, price
of hardener is not a factor to me at all... and as you see above, the
process costs more than the ingredients.

--
Ryuji Suzuki
"People seldom do what they believe in.  They do what is convenient,
then repent." (Bob Dylan, Brownsville Girl, 1986)