It seems natural to try a larger excess H2O2 and HCl? Do it in the cold.

Hello everyone,

I have some question regarding to aforementioned reaction - as of my experience procedure copy from HBr/H2O2 where man use 1eq carbonyl, 1.1eq HBr and 1.4eq H2O2 but using HCl instead do not lead to full conversion.


As of my TLC for such procedure using HBr I received 100% conversion and selectivity to monobrominated product.

While using HCl I received mostly monobrominated product, some significant part of substrate and little trace of something more unpolar (dibromo derivative?)



As of my literature research it can happen due to slow reaction between h2o2 and HCl and even below 30% conc of hcl chlorine is not appearing at all, instead of this HCl is slowly decomposing H2O2 to oxygen and water.


Question to You - is it possible to somehow challenge this problem and use this procedure or it is rather not recommended? I also didnt find any work or patent on such reaction (monochlorination of carbonyls by h2o2/hcl).

Try contacting Elutia.  They make a TEA (Thermal Energy Analyzer) instrument. We used it to test for n- nitrosamines.  It first came out under Thermo, but I think Ellutia bought it from them.  The idea of the analyzer was to take the substances routed from a GC, pyrolyze them as they came out, then they were run through a could trap ( ours used EtOH and dry ice) and the left over gas went to the instrument.  The Instrument took the gasses (NOx) and reacted it with O3( O2 came in and was exposed to an electric arc to make ozone).  This chemoluminesced to produce red light which was measured.  There were other steps, but you get the.idea.  They might be able to help you.

Are you sure it is related to the OP question?

Can't think of anything that can be done.

Reaction speed basically depends of concentrations (or pressure) and temperature - if you keep these constant, reaction speed doesn't change.

You can speed up the reaction with catalyst or slow it down with an inhibitor - but that requires adding something to the mix (changing container material won't change much, as this particular reaction takes place in the bulk).

Sometimes it is possible to speed up the reaction with ionizing radiation (UV and dental cement for example), but that's opposite of what you need.

What is the purpose  to do so.
I think you can only decrease pressure or rise temperature.
Also removing oxygen will shift to NO.