Abstract: A method for inhibiting the premature polymerization of styrenic monomers is disclosed wherein the method comprises adding to said monomers a combination of: (A) at least one inhibitor that is a sulfonic acid compound in a concentration sufficient to initiate cationic polymerization of said styrenic monomers at any point of the manufacturing or purification process and cause a resulting temperature increase; and (B) at least one amine in a concentration sufficient to reduce said cationic polymerization and said temperature increase; whereby an uncontrolled exothermic reaction between said sulfonic acid compound and said styrenic monomers will be prevented.

Abstract: A method for inhibiting the premature polymerization and the polymer growth of ethylenically unsaturated monomers is disclosed wherein the method comprises adding to said monomers an effective amount of at least one hydrogen donor or electron acceptor. In a preferred embodiment, the hydrogen donor or electron acceptor is used in combination with a stable nitroxyl free radical.

Abstract: Disclosed herein is a method for inhibiting and retarding the premature polymerization and the polymer growth of vinyl aromatic monomers wherein the method comprises adding to said monomers an effective amount of an inhibitor and retarder blend comprising: (A) at least one aromatic sulfonic acid; (B) at least one amine; (C) at least one nitrophenol; and (D) at least one member of the group consisting of nitroxy radical-containing compounds and nitrosoanilines.

Abstract: Disclosed herein is a method for inhibiting and retarding the premature polymerization and the polymer growth of vinyl aromatic monomers wherein the method comprises adding to said monomers an effective amount of an inhibitor and retarder blend comprising: (A) at least one aromatic sulfonic acid; (B) at least one amine; (C) at least one nitrophenol; and (D) at least one member of the group consisting of nitroxy radical-containing compounds and nitrosoanilines.

Abstract: A method for inhibiting the premature polymerization and the polymer growth of ethylenically unsaturated monomers is disclosed wherein the method comprises adding to said monomers an effective amount of at least one hydrogen donor or electron acceptor. In a preferred embodiment, the hydrogen donor or electron acceptor is used in combination with a stable nitroxyl free radical.

Abstract: Disclosed herein is a method for inhibiting and retarding the premature polymerization and the polymer growth of vinyl aromatic monomers wherein the method comprises adding to said monomers an effective amount of an inhibitor and retarder blend comprising: (A) at least one aromatic sulfonic acid; (B) at least one amine; (C) at least one nitrophenol; and (D) at least one member of the group consisting of nitroxy radical-containing compounds and nitrosoanilines.

Abstract: Disclosed herein is a method for inhibiting and retarding the premature polymerization and the polymer growth of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor that is a sulfonated nitrophenol of the formula: wherein: R1, R2, and R3 are independently selected from the group consisting of hydrogen, alkyl, NO2, and SO3H, provided that at least one of R1, R2, and R3 is NO2 and at least one of R1, R2, and R3 is SO3H. In a preferred embodiment, at least one additional inhibitor selected from the group consisting of nitroxyl compounds, nitrosoanilines, nitrophenols, amines, and mixtures thereof is also added.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds. Also disclosed is a composition of matter comprising: A) an ethylenically unsaturated monomer and B) an effective inhibiting amount, sufficient to prevent premature polymerization during distillation or purification of said ethylenically unsaturated monomer, of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds used together with an effective amount of oxygen or air to enhance the inhibiting activity of said inhibitor.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds. Also disclosed is a composition of matter comprising: A) an ethylenically unsaturated monomer and B) an effective inhibiting amount, sufficient to prevent premature polymerization during distillation or purification of said ethylenically unsaturated monomer, of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds used together with an effective amount of oxygen or air to enhance the inhibiting activity of said inhibitor.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of: A) at least one first inhibitor selected from the group consisting of C-nitrosoaniline compounds; and B) at least one second inhibitor selected from the group consisting of quinone alkides, nitroaromatic compounds, hydroxylamine compounds, phenylenediamine compounds, quinone compounds, and hydroquinone compounds. Also disclosed is a composition of matter comprising: A) at least one member selected from the group consisting of C-nitrosoaniline compounds; and B) at least one member selected from the group consisting of quinone alkides, nitroaromatic compounds, hydroxylamine compounds, phenylenediamine compounds, quinone compounds, and hydroquinone compounds.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds. Also disclosed is a composition of matter comprising: A) an ethylenically unsaturated monomer and B) an effective inhibiting amount, sufficient to prevent premature polymerization during distillation or purification of said ethylenically unsaturated monomer, of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds used together with an effective amount of oxygen or air to enhance the inhibiting activity of said inhibitor.

Abstract: A method is disclosed for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers a polymerization inhibiting amount of a mixture comprising A) a first inhibitor comprising 4-amino-2,2,6,6-tetramethylpiperidinyloxy, wherein said amino group is a primary, secondary, or tertiary amino group; and B) at least one other inhibitor having the structural formula: wherein: R1 and R4 are independently selected from the group consisting of hydrogen, alkyl, and heteroatom-substituted alkyl; R2 and R3 are independently selected from the group consisting of alkyl and heteroatom-substituted alkyl; X1 and X2 (1) are independently selected alkyl groups of 1 to 15 carbon atoms or (2) taken together, form a ring structure with the nitrogen.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of a mixture comprising: A) at least one stable hindered nitroxyl compound having the structural formula: wherein R1 and R4 are independently selected from the group consisting of hydrogen, alkyl, and heteroatom-substituted alkyl and R2 and R3 are independently selected from the group consisting of alkyl and heteroatom-substituted alkyl; and X1 and X2 (1) are independently selected from the group consisting of halogen, cyano, COOR7, —S—COR7, —OCOR7, (wherein R7 is alkyl or aryl), amido, —S—C6H5, 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 inhibitor selected from the group consisting of ortho-quinone, ortho-hydroquinone, para-quinone, para-hydroquinone, and derivatives of the foregoing.

Abstract: A method is disclosed for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers a polymerization inhibiting amount of a mixture comprising

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of at least one inhibitor selected from the group consisting of C-nitrosoaniline and quinone imine oxime compounds.

Abstract: An improved process for the production and purification of unsaturated monomers employing nitroxyl-containing inhibitors wherein process streams containing the inhibitor are recycled is disclosed, wherein the improvement comprises recycling said streams at a reboiler temperature no higher than about 110° C.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of a mixture comprising: