Patent ID: 7045647

Claim:
A method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of: A) at least one nitroxyl compound of the structure: wherein R 1 and R 4 are independently selected from the group consisting of hydrogen, alkyl, and heteroatom-substituted alkyl and R 2 and R 3 are (1) independently selected from the group consisting of alkyl and heteroatom-substituted alkyl or (2) taken together, form a ring structure with the nitrogen, and wherein the ring is selected from the group consisting of piperidine, pyrrolidine, pyridine and pyrrole; and X 1 and X 2 (1) are independently selected from the group consisting of halogen, phosphorus (in any of it oxidation states), cyano, COOR 7 , —S—COR 7 , —OCOR 7 , —S—R 7 (wherein R 7 is alkyl or aryl), amido, carbonyl, alkenyl, or alkyl of 1 to 15 carbon atoms, or (2) taken together, form a ring structure with the nitrogen, and B) at least one quinone alkide compound of the formula wherein: R 31 and R 32 are independently alkyl of 4 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms or phenylalkyl of 7 to 15 carbon atoms, and R 33 is —CN, —COOH, —COOR 34 , —COR 35 , —OCOR 36 , —CONR 37 R 38 or —PO(OR 39 ) 2 where R 34 is alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenyl or benzyl, R 35 is alkyl of 1 to 18 carbon atoms, aryl of 6 to 10 carbon atoms or said aryl substituted by 1 or 2 alkyl of 1 to 4 carbon atoms or by hydroxyl, R 36 is alkyl of 1 to 18 carbon atoms, aryl of 6 to 10 carbon atoms or said aryl substituted by 1 or 2 alkyl of 1 to 4 carbon atoms or by hydroxyl, R 37 and R 38 are independently hydrogen, alkyl of 1 to 18 carbon atoms or said alkyl substituted by alkylamino of 1 to 4 carbon atoms, by dialkylamino of 2 to 8 carbon atoms or by hydroxyl; benzyl, aryl of 6 to 10 carbon atoms or said aryl substituted by alkyl of 1 to 4 carbon atoms, by alkylamino of 1 to 4 carbon atoms, by dialkylamino of 2 to 8 carbon atoms, by phenylamino or by hydroxyl, R 39 is hydrogen or alkyl of 1 to 18 carbon atoms, and R 40 is hydrogen, alkyl, aryl, hydroxyl, alkoxy, —CN, —COOH, —COOR 34 , —COR 35 , —OCOR 36 , —CONR 37 R 38 or —PO(OR 39 ) 2 .