Bis(trimethylsilyl) sulfate-silica has been shown to be an efficient reagent system for promoting thioacetalisation of carbonyl compounds at room temperature.

It was established by IR spectroscopy and chemical analysis that bis(trimethylsilyl) sulfate reacts chemically with isolated silanol groups of silica even at room temperature, and is quantitatively chemisorbed at 373 K. Sulfidation of the silica does not occur. Chemisorption of [(CH3)3Si]2SO4 on the surface of silicon(IV) oxide is not complicated by side processes.

Le sulfate de bis (triméthylsilyle) composé aisément accessible, permet d'introduire le groupe sulfonique dans des dérivés fonctionnels tels que les éthers aromatiques, les chlorures et anhydrides d'acides aliphatiques, sans qu'il y ait de modifications notables de la fonction considerée. Dans le cas d'in chlorure d'acide alpha-chloré, on observe cependant une disulfonation accompagnée de decarboxylation.

The disclosed compounds are adducts of imidazole or derivatives thereof and sulfur dioxide. The adducts are apparently of the Lewis acid - Lewis base type, and are useful as latent curing agents for epoxide resins. The adducts are prepared by interacting the imidazole and sulfur dioxide under anhydrous conditions. Equimolar imidazole-SO2 adducts can serve as a source of sulfur dioxide at room temperature.

The disclosed compounds are adducts of imidazole or derivatives thereof and sulfur dioxide. The adducts are apparently of the Lewis acid-Lewis base type, and are useful as latent curing agents for epoxide resins. The adducts are prepared by interacting the imidazole and sulfur dioxide under anhydrous conditions. Equimolar imidazole-SO2 adducts can serve as a source of sulfur dioxide at room temperature.

This invention relates to a process for curing polyepoxides. More particularly, this invention relates to a new process for curing polyepoxides, to novel curing agents used in the process, and to useful products obtained from the process.