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Can someone draw the reaction that leads to the generation of HOCl when dichloroisocyanuric acid (structure shown below) is dissolved in water?

enter image description here

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It would be preferable if you would propose a mechanism and someone can verify it (or even better, find the portion of the reaction that's troublesome for you and ask more about its concepts). –  jonsca Dec 5 '12 at 2:32
    
If I could do that I wouldn't ask the question. –  Richardbernstein Dec 5 '12 at 14:45
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Well, it doesn't have to be perfect, but I'm certain you'll get a better grasp on the concepts that way. Think about the overall reaction and what species are being oxidized and which are being reduced. –  jonsca Dec 5 '12 at 22:35
    
Ma'am, I have a phd in biochemistry from Rockefeller university. I was a straight a undergrad at Cornell in biochemistry. But I've forgotten ALL the basics (as well as the rest of it). So how about just showing me the reaction. –  Richardbernstein Dec 6 '12 at 3:19
    
I'll admit, I'm quite in awe of your credentials. I gave quite a bit of thought to becoming an academic neurologist at one point. We do try to uphold standards for users to make an attempt at a question and apply them to everyone because it's hard to draw a line at what constitutes a "homework" versus an applied problem. I'll let it stand and see if someone has an answer for you (I don't actually have an answer for it, I'd have to sit down with it), but I think that others would be more willing to help if you had added a structure with some oxidation states or something. –  jonsca Dec 6 '12 at 4:41

2 Answers 2

$N-Cl$ bond is polarized toward nitrogen: $N^--Cl^+$ This means, that any chloramine can produce $HOCl$ in water by mean of hydrolysis of $N-Cl$ bond.

$$\ce{R2NCl + H2O -> R2NH + HOCl}$$

The mechanism is more subtle matter. Basically, it should be one of $S_N$ mechanisms, but it is hard to choose right one here ($S_N1$ or $S_N2$). The central atom in mechanism here should be $Cl$, and $R_2N^-$ is leaving group.

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To build on permekra's answer, I have drawn a mechanism. I think that is would be SN2 (due to the unlikeliness of $\ce{Cl+}$).

dichlor hydrolysis mechanism

Water attacks a chlorine atom as a nucleophile, and the chloroisocynurate anion leaves resulting in $\ce{H2OCl+}$. The chloroisocyanurate anion can act as a leaving group due to its resonance stabilization (see below). Then, the chloroisocyanurate anion depropotonates $\ce{H2OCl+}$ to form choroisocyanuric acid and hypochlorous acid.

enter image description here

Finally, since there is another chlorine atom, this substitution reaction occurs again to form cyanuric acid $\ce{(NCOH)3}$ and another equivalent of $\ce{HOCl}$. The net reaction for the hydrolysis is:

$$\ce{ C3HCl2N3O2 + 2H2O -> C3H3N3O3 + 2HOCl}$$

For curiosity - the sodium salt of dichloroisocyanuric acid is the active ingredient in the household cleaning product Comet.

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This is PRECISELY what I was looking for. Thank you very much. And see my next question as follow up. –  Richardbernstein Dec 7 '12 at 16:38

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