Hydroxymethanesulfonic acid has the unusual property that it can be removed from a mixture by reducing the pressure, whereupon it decomposes to formaldehyde, water, and sulfur dioxide gas which are all easily swept out of a mixture.
Perhaps hydroxymethanesulfonic acid can be used as a solvent replacement for sulfuric acid which is decidedly non-volatile.
Because it is still an aqueous acid the solvent leveling effect means it cannot support anything more acidic than the hydronium ion. Nevertheless, it can be employed at high concentrations of these hydronium ions to increase the rate of hydrolysis of functional groups.
It would accelerate the hydrolysis, for example, of sterically
hindered esters which could not easily access a tetrahedral transition state, or be used to convert cyanohydrins to hydroxycarboxylic acids.
⍺-Hydroxycarboxylic acid can be a protected ketone or aldehyde that can be deprotected by periodic acid cleavage. In this way, a neutral molecule could be handled as a carboxylic acid up until a final unmasking step.
Hydroymethanesulfonic acid could be usefully used in an acid treatment of any substrate attached to a polymeric resin because it would not need to be removed from the resin by exhaustive washing. Instead, the resin could be filtered and dried under reduced pressure. Hydroymethanesulfonic acid would dissociate and evaporate away.
The green solvent glycerol cannot be freed of sulphuric acid by evaporation of the acid and if it is neutralized the inorganic salts will be trapped in the high boiling solvent. A possible solution is to replace sulphuric acid with hydroxymethanesulfonic acid. This acid can be removed by heating under reduced pressure whereupon it degrades to sulfur dioxide, formaldehyde, and water; all of which can be easily evaporated away.
The volatile strong acids HCl or HBr would react with glycerol irreversibly while there is a good chance that hydroxymethylsulfonic acid would be stable in it.
Hydroxymethanesulfonic acid solution mixed into a higher boiling dipolar aprotic solvent such as dimethylsulfoxide. This mixture might provide greater solubility for organic substrates, a higher reaction temperature, adequate water concentration for reaction, and the capacity to remove both excess water and the acid by heating under reduced pressure.
Hydroxymethanesulfonic acid can be anticipated to be a strong acid of choice when trying acid-catalyzed reactions involving functionalized polymers since it can be removed by placing the resin under a vacuum.
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