be reused or reutilized for example indium or indium tin oxide can be recovered from thin films held together in devices typically employing epoxy adhesives such as cellular telephones portable television screens and the like the compounds of formula i can be used as hardeners in epoxy compositions to achieve cured compositions that can be degraded in acidic conditions ranging from weakly to strongly acidic conditions such a strategy is attractive because it allows common resins to be combined with novel hardeners for the formation of epoxies with a variety of mechanical adhesive electronic thermal etc properties while enabling them to be disassembled dissolved or reworked the development of epoxy systems employing acid labile hardeners where the cured resin can rapidly disassemble under mildly acidic conditions while maintaining mechanical and adhesive integrity in the ambient environment as described in this invention are unknown in the prior art as such the present invention also provides 1 the use of orthoesters to produce hardener components of epoxy compositions that enable useful degradation properties including degradation under mildly acidic conditions 2 the use of formal ketal acetal moieties suitable derivatives and analogs as hardener component in epoxy compositions 3 the use of orthocarbonate moieties suitable derivatives and analogs as hardener component in epoxy compositions 4 the use of ketal acetal orthoester or orthocarbonate based epoxy resins with non degradable polyamine or polythiol hardener components to provide compositions that enable useful degradation properties including degradation under mildly acidic conditions set forth below are examples of the compounds of this invention and methods of making and using them they are intended to be illustrative and not to be constructed as limiting the scope of.