= Solution
Ring cleavage of <1,3,5-Trioxane> regenerates \b[<formaldehyde>], whose strong <carbon>–<oxygen> <pi bond> stabilizes the monomer; in water much of it is further stabilized as its hydrate. <acetal hydrolysis>, particularly under acid catalysis, provides a route between the cyclic trimer and these monomeric forms.
The corresponding formal depolymerization of a <siloxane> would create \b[$\mathrm{R_2Si=O}$ <silanone> units]. Such ordinary small-substituent <silanones> have much less favourable pi bonding and are very reactive toward forming new Si–O–Si linkages. The connected <siloxane> is consequently preferred over a persistent aqueous solution of <silanone> monomers. This explains the intended contrast, but aqueous stability is conditional: acid or base can catalyse <siloxane> cleavage to <silanols>, and those <silanols> can condense again. Neither neutral-water inertness of every <siloxane> nor instantaneous neutral-water dissociation of every trioxane should be inferred.
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