Sciencemadness Discussion Board

How do organic acid salts behave in hypochlorite?

Random - 22-10-2013 at 10:11

I think I read that benzoates get chlorinated to chlorobenzoates. What happens with acetates?

DraconicAcid - 22-10-2013 at 10:18

I doubt that acetates would react with hypochlorite. I've used hypochloite/acetic acid mixtures to oxidize alcohols.

deltaH - 22-10-2013 at 10:41

Chlorine may be produced by the acidification of bleach and chlorine can also be reacted with acetic acid to form chloroacetic acids, however, if this would actually proceed under your specific conditions is another story :) Would certainly be unlikely under dilute conditions.

Random - 22-10-2013 at 10:48

Some chlorine definitelly should give off chloroacetic acids in acidic solution but then again that would be mostly reaction with chlorine. I was wondering if hypochlorite reacts in alkaline solutions.

Why wouldn't it happen in dilute 5% NaClO?

[Edited on 22-10-2013 by Random]

deltaH - 22-10-2013 at 11:03

That's over my head random... I'll leave it to bigger and better brains ;)

As an aside... maybe related, I know you can prepare peracetic acid by reacting acetic acid and peroxide under fairly aggressive conditions (long reaction times, high concentrations and in the pressence of sulfuric acid as catalyst), so I would say from that, that acetic acid is strongly resistant to oxidation... however, clearly it can be chlorinated, but chlorination is another animal to oxidation and I think at high pH, hypochlorite is less able to act as a chlorination reaction and more as a straight oxidant (to which acetates are mostly resistant).

Oops, I have nevertheless attempted an answer, sorry lol

[Edited on 22-10-2013 by deltaH]

woelen - 22-10-2013 at 11:09

If you want to oxidize acetic acid, then there are two options:
1) Breaking the C-skeleton;
2) Oxidizing the CH3-group.
The -COOH group already is fully oxidized.

CH3-groups are not easily oxidized under mild conditions. When the saturated hydrocarbon-based compounds are heated to a few hundreds degrees C, then they can be oxidized, but this usually is accompanied with complete breakdown of the C-skeleton.

I can imagine that when hypochlorite is allowed to act upon acetate ion for sufficiently long time and at sufficiently high temperature, that is destroys the acetate ion completely and that it is oxidized to carbonate ion. But at the same time hypochlorite is unstable at high temperature (disproportionates to the much less oxidizing chlorate and chloride) and I think that before acetate can be oxidized appreciably, most of the hypochlorite is destroyed already.

AJKOER - 23-10-2013 at 10:33

Some recent research suggests that the acetate ion can be acted on by hypochlorous acid (from the action of chlorine and water) and I would include photolysis conditions. To quote a 2000 paper (link: http://pubs.acs.org/doi/abs/10.1021/ic991486r ):

"Acetic acid has a second catalytic role through the formation of acetyl hypochlorite, which is much more reactive than HOCl in the transfer of Cl+ to ClO2- to form ClOClO."

Also, per another article, "Effect of Chloride Ion on the Kinetics and Mechanism of the Reaction between Chlorite Ion and Hypochlorous Acid" link:
http://www.researchgate.net/publication/23141635_Effect_of_c... , to quote:

"Moreover, they found that acetate ion accelerates the formation of ยท ClO2 enormously."

Also:

"It was interpreted by a steady-state formation and further reactions of acetyl hypochlorite. "

Cited reactions involving this chlorine species include:

Cl2O2+ H2O --> ClO3- + Cl- + 2 H+ (page 2 eq 5)
Cl2O2 + HOCl --> ClO3- + Cl2 + H+ (page 2 eq 8)

where the acetate ion appears to foster the formation of an active chlorine species. Pertinent to the above thread, Acetyl hypochlorite formation is suggested together with its subsequence catalyst role.


[Edited on 23-10-2013 by AJKOER]