Control of pH in acidic range by thermal degradation

[uby]

Hi all,

Long time lurker, very seldom poster.

I have a need for an aqueous soluble compound that will thermally decompose or oxidize to form acidic products in the temperature range 100-300 C.

It's well known that, on the other end of the scale, urea is water-soluble and near-neutral pH at room temperature but will decompose into a variety of products but most importantly ammonia (which dissolves in water to form ammonium ions, thereby raising the pH of the solution considerably). However, I've had considerable difficulty finding anything that can perform a similar function and make the solution more acidic.

The best thing I've found is ethylene glycol, which will oxidize to form ethylene oxide, some ethers, and release free protons. In practice, however, this is a pretty slow process and takes many days to equilibrate.

I'd greatly appreciate any advice or suggestions from more experienced chemists!

Thanks,
--Dave

 

[GCT]

Hi all,

Long time lurker, very seldom poster.

I have a need for an aqueous soluble compound that will thermally decompose or oxidize to form acidic products in the temperature range 100-300 C.

It's well known that, on the other end of the scale, urea is water-soluble and near-neutral pH at room temperature but will decompose into a variety of products but most importantly ammonia (which dissolves in water to form ammonium ions, thereby raising the pH of the solution considerably). However, I've had considerable difficulty finding anything that can perform a similar function and make the solution more acidic.

The best thing I've found is ethylene glycol, which will oxidize to form ethylene oxide, some ethers, and release free protons. In practice, however, this is a pretty slow process and takes many days to equilibrate.

I'd greatly appreciate any advice or suggestions from more experienced chemists!

Thanks,
--Dave

Products of transesterfication are acidic and yield compounds such as acetic acid and alcohols upon autoclaving. I used to autoclave solutions containing anhydrides and esters - the resulting solution was relatively more acidic.

 

[uby]

hi GCT,

thanks for your input! i am currently working with the formic acid/sodium formate system to test for feasibility, and will move to some of the more complex esters if i cannot induce enough of a pH change.

--dave