Methods and compositions for inhibiting vinyl aromatic monomer polymerization

A method for inhibiting the polymerization of vinyl aromatic monomer comprising adding to said monomer an effective polymerization inhibiting amount of a compound comprising (A) a quinone methide derivative having the formula

• wherein:
• R1 and R2 are independently H, C4 to C18alkyl;
• C5 to C12 cycloaklyl;
• or C7 to C15 phenylalkyl, and
• R3 is aryl, or aryl substituted with C1 to C6 alkyl, alkoxy, hydroxy, nitro, amino, carboxy, or mixtures thereof;
• and
• (B) a phenol compound having the formula
• wherein R4 and R5 may be the same or different and are chosen from C1-C20 alkyl, C1-C30 alkaryl and substituted C1-C30 alkaryl;
• R6, when present, is selected from C1-C20 alkyl, thiophenol, substituted thiophenol, C1-C40 alkanoic acid ester, C1-C30 alkaryl, substituted C1-C30 alkaryl, C1-C6 alkylamino, C1-C6 alkoxy, amine, polynuclear aryl and substituted polynuclear aryli.