Blends of quinone alkide and nitroxyl compounds as polymerization inhibitors

1. A composition comprising:

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 X 1 and X 2 (1) are independently selected from the group consisting of halogen, phosphorus (in any of its 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; or

—NR 37 R 38 is morpholino, piperidino or pyrrolidino,

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 .

2. The composition of claim 1 wherein the nitroxyl compound has the structural formula:

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 independently selected from the group consisting of alkyl and heteroatom-substituted alkyl, and the

portion represents the atoms necessary to form a five-, six-, or seven-membered heterocyclic ring.

3. The composition of claim 1 wherein the nitroxyl compound is selected from the group consisting of:

2,2,6,6-tetramethyl-piperidinyloxy;

4-amino-2,2,6,6-tetramethyl-piperidinyloxy;

4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy;

4-oxo-2,2,6,6-tetramethyl-piperidinyloxy;

4-dimethylamino-2,2,6,6-tetramethyl-piperidinyloxy;

4-ethanoyloxy-2,2,6,6-tetramethyl-piperidinyloxy;

2,2,5,5-tetramethylpyrrolidinyloxy;

3-amino-2,2,5,5-tetramethylpyrrolidinyloxy;

2,2,4,4-tetramethyl-1-oxa-3-azacyclopentyl-3-oxy;

2,2,4,4-tetramethyl-1-oxa-3-pyrrolinyl-1-oxy-3-carboxylic acid;

2,2,3,3,5,5,6,6-octamethyl-1,4-diazacyclohexyl-1,4-dioxy;

4-bromo-2,2,6,6-tetramethyl-piperidinyloxy;

4-chloro-2,2,6,6-tetramethyl-piperidinyloxy;

4-iodo-2,2,6,6-tetramethyl-piperidinyloxy;

4-fluoro-2,2,6,6-tetramethyl-piperidinyloxy;

4-cyano-2,2,6,6-tetramethyl-piperidinyloxy;

4-carboxy-2,2,6,6-tetramethyl-piperidinyloxy;

4-carbomethoxy-2,2,6,6-tetramethyl-piperidinyloxy;

4-carbethoxy-2,2,6,6-tetramethyl-piperidinyloxy;

4-cyano-4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy;

4-methyl-2,2,6,6-tetramethyl-piperidinyloxy;

4-carbethoxy-4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy;

4-hydroxy-4-(1-hydroxypropyl)-2,2,6,6-tetramethyl-piperidinyloxy;

4-methyl-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine-1-oxyl;

4-carboxy-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine-1-oxyl;

4-carbomethoxy-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine-1-oxyl;

4-carbethoxy-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine-1-oxyl;

4-amino-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine-1-oxyl;

4-amido-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine-1-oxyl;

3,4-diketo-2,2,5,5-tetramethylpyrrolidinyloxy;

3-keto-4-oximino-2,2,5,5-tetramethylpyrrolidinyloxy;

3-keto-4-benzylidine-2,2,5,5-tetramethylpyrrolidinyloxy;

3-keto- 4 ,4-dibromo-2,2,5,5-tetramethylpyrrolidinyloxy;

2,2,3,3,5,5-hexamethylpyrrolidinyloxy;

3-carboximido-2,2,5,5-tetramethylpyrrolidinyloxy;

3-oximino-2,2,5,5-tetramethylpyrrolidinyloxy;

3-hydroxy-2,2,5,5-tetramethylpyrrolidinyloxy;

3-cyano-3-hydroxy-2,2,5,5-tetramethylpyrrolidinyloxy;

3-carbomethoxy-3-hydroxy-2,2,5,5-tetramethylpyrrolidinyloxy;

3-carbethoxy-3-hydroxy-2,2,5,5-tetramethylpyrrolidinyloxy;

2,2,5,5-tetramethyl-3-carboxamido-2,5-dihydropyrrole-1-oxyl;

2,2,5,5-tetramethyl-3-amino-2,5-dihydropyrrole-1-oxyl;

2,2,5,5-tetramethyl-3-carbethoxy-2,5-dihydropyrrole-1-oxyl;

2,2,5,5-tetramethyl-3-cyano-2,5-dihydropyrrole-1-oxyl;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipate;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)sebacate;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)n-butylmalonate;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)phthalate;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)isophthalate;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)terephthalate;

bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)hexahydroterephthalate;

N,N′-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipamide;

N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-caprolactam;

N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-dodecylsuccinimide;

2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)]-s-triazine; and

4,4′-ethylenebis(1-oxyl-2,2,6,6-tetramethylpiperazin-3-one).

4. The composition of claim 1 wherein the quinone alkide is selected from the group consisting of:

(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetonitrile,

(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetic acid,

(3,5-di-tert-amyl-4-oxocyclohexa-2,5-dienylidene)acetic acid,

methyl (3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetate,

ethyl (3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetate,

n-butyl (3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetate,

2,6-di-tert-butyl-4-(2-oxopropylidene)-cyclohexa-2,5-dienone,

diethyl (3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)methanephosphonate,

(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)methyl acetate,

(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)methyl pivalate,

(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)methyl benzoate, and

N,N-diethyl-2-(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetamide.

5. The composition of claim 1 wherein the quinone alkide compound is 3,5-di-t-butyl-4-oxo-cyclohexa-2,5-dienylidene acetic acid.

6. The composition of claim 1 wherein the quinone alkide compound is an alkyl 3,5-di-t-butyl-4-oxo-cyclohexa-2,5-dienylidene acetic acid.

7. The composition of claim 1 wherein the nitroxyl compound is 4-oxo-2,2,6,6-tetramethyl piperidinyloxy.

8. The composition of claim 5 wherein the nitroxyl compound is 4-oxo-2,2,6,6-tetramethyl piperidinyloxy.

9. The composition of claim 6 wherein the nitroxyl compound is 4-oxo-2,2,6,6-tetramethyl piperidinyloxy.