Sciencemadness Discussion Board

Action of Nascent Hydrogen on Hypochlorite

AJKOER - 3-12-2019 at 10:13

I just find a possible confirmation of the reaction of the hydrogen radical also referred to as the hydrogen atom or H chemisorbed (see https://www.sciencemadness.org/whisper/viewthread.php?tid=10... ) and also nascent hydrogen, acting upon hypochlorite. My suggested reaction is:

∙H + OCl- --> ∙OHCl-

A reference for the above radical can be found at https://www.sciencemadness.org/whisper/viewthread.php?tid=15... .

At pH > 5, the above radical decomposes as follows:

∙OHCl- --> ∙OH + Cl-

Partial confirmation from a dated source, namely Mellor (see https://books.google.com/books?id=8w1GAQAAMAAJ&pg=PA278&... ) who notes that the action of nascent hydrogen, as created in electrolysis, on hypochlorite does result in an increase in chloride.
--------------------------------

For completeness at pH < 5 (more acidic conditions):

∙OHCl- --> OH- + ∙Cl

∙Cl + ∙Cl = Cl2

Cl2 + H2O = HCl + HOCl
............

[Edited on 4-12-2019 by AJKOER]

Ubya - 3-12-2019 at 11:51

ok

DraconicAcid - 3-12-2019 at 12:02

Nascent hydrogen can reduce hypochlorite to chloride? What a discovery!

This solves all my challenging difficulties in finding a convenient way to generate chloride ion in situ!

unionised - 3-12-2019 at 12:15

I suspect there may be a competing reaction.
H. + H2O --> OH. + H2

However, even if I'm wrong it's hard to see the reaction with OCl- as useful.

AJKOER - 3-12-2019 at 16:26

Accepting the nascent hydrogen path to the ∙OHCl- radical and its decomposition products in addition to chloride:

∙OHCl- ---> .OH + Cl- (pH >5)

also implies an active presence of hydroxyl radicals. And further reactions in the presence of hypochlorite creating its radical counterpart:

∙OH + OCl- ---> OH- + ∙OCl

And, a set of radical reactions:

∙OCl + ∙OCl = (OCl)2 or (ClO)2

∙OCl + ∙OCl = O2 + Cl2

∙OCl + ∙OCl = ∙ClOO + ∙Cl

∙OCl + ∙OCl = ∙OClO + ∙Cl

where ∙OClO is more frequently written as ClO2, where chlorine dioxide is a precursor to chlorates (as is also the process of electrolysis of hypochlorite a path to ClO3- per Mellor).

So, one possible implication, as there are many paths to .H other than, for example, electrolysis, it follows there could be several competing paths to chlorate as well. Note, while some hydrogen radical presence may add to favorably to radical activity, an excess of .H itself may directly consume formed chlorate!

[Edited on 4-12-2019 by AJKOER]

AJKOER - 3-12-2019 at 16:47

Quote: Originally posted by unionised  
I suspect there may be a competing reaction.
H. + H2O --> OH. + H2

However, even if I'm wrong it's hard to see the reaction with OCl- as useful.


It is best to view .H as an operating couple (e-,H+) as:

H+ + e- = .H

in an apparent equilibrium reaction, in my assessment. So, its reaction with water:

(e-,H+) + (H+ + OH-) = .H + H2O

and the hydrogen radical could regenerate itself barring the termination reaction:

.H + .H --> H2
------------------------------------------------------------------

Also, the action of (e-,H+) on hypochlorite in steps:

(e-,H+) + OCl- = e- + HOCl

e- + HOCl = .OHCl-

which some may find more preferable than my proposed reaction in the opening of this thread:

∙H + OCl- --> ∙OHCl-

[Edited on 4-12-2019 by AJKOER]