The Depletion of Substituted Phenolic Stabilizers by Conjugate C‐Addition to Acrylic Monomers in Multicomponent Systems

The depletion of selected substituted phenol stabilizers from systems simulating self‐etching dental adhesives is studied. If the adhesive monomer is an acrylate derivative, the stabilizer disappears quickly. Experimental results support the hypothesis that the phenol stabilizers are depleted from the system via a non‐radical reaction with the acrylic double bond in addition to the free‐radical mechanism. The C‐conjugate addition of aryloxide anions to the acrylate double bonds (the Michael reaction) is proposed as the reaction mechanism. The rate of the acid‐catalyzed Michael addition between acrylate monomers and phenolic stabilizers depends on the strength of the acidic catalyst.