The present invention is directed to a purification method for purifying a fluorine-containing polymerizable monomer of the formula (1), in which the fluorine-containing polymerizable monomer is purified by distillation in the coexistence of a phenolic compound A such as 6-tert-butyl-2,4-xylenol and a phenolic compound B such as 2,2′-methylene-bis(4-methyl-6-tert-butylphenol).

##STR00001##

By the combined use of the phenolic compound A and the phenolic compound B, it is possible to significantly suppress polymerization or oligomerization of the fluorine-containing polymerizable monomer even during industrial-production-scale distillation and efficiently purify the fluorine-containing polymerizable monomer by distillation.

The present invention is directed to a purification method for purifying a fluorine-containing polymerizable monomer of the formula (1), in which the fluorine-containing polymerizable monomer is purified by distillation in the coexistence of a phenolic compound A such as 6-tert-butyl-2,4-xylenol and a phenolic compound B such as 2,2′-methylene-bis(4-methyl-6-tert-butylphenol).

##STR00001##

By the combined use of the phenolic compound A and the phenolic compound B, it is possible to significantly suppress polymerization or oligomerization of the fluorine-containing polymerizable monomer even during industrial-production-scale distillation and efficiently purify the fluorine-containing polymerizable monomer by distillation.

The present invention is directed to a purification method for purifying a fluorine-containing polymerizable monomer of the formula (1), in which the fluorine-containing polymerizable monomer is purified by distillation in the coexistence of a phenolic compound A such as 6-tert-butyl-2,4-xylenol and a phenolic compound B such as 2,2′-methylene-bis(4-methyl-6-tert-butylphenol).

##STR00001##

By the combined use of the phenolic compound A and the phenolic compound B, it is possible to significantly suppress polymerization or oligomerization of the fluorine-containing polymerizable monomer even during industrial-production-scale distillation and efficiently purify the fluorine-containing polymerizable monomer by distillation.

A synergistic polymerization inhibitor composition, the composition having a copper salt, and a manganese salt; a copper salt or a manganese salt, and a cationic polymer; or a phenothiazine and a manganese salt. A method for inhibiting polymerization of unsaturated polymerizable monomers, the method providing adding a synergistic polymerization inhibitor composition to an methacrylic acid manufacturing system or component thereof, the composition having a copper salt, and a manganese salt; a copper salt or a manganese salt, and a cationic polymer; or a phenothiazine and a manganese salt.

A synergistic polymerization inhibitor composition, the composition having a copper salt, and a manganese salt; a copper salt or a manganese salt, and a cationic polymer; or a phenothiazine and a manganese salt. A method for inhibiting polymerization of unsaturated polymerizable monomers, the method providing adding a synergistic polymerization inhibitor composition to an methacrylic acid manufacturing system or component thereof, the composition having a copper salt, and a manganese salt; a copper salt or a manganese salt, and a cationic polymer; or a phenothiazine and a manganese salt.

Described are methods and compositions for inhibiting polymerization of a monomer (e.g., styrene) composition using a hydroxylated quinone antipolymerant. The hydroxylated quinone antipolymerant can be used with little or no nitroxyl group containing antipolymerant yet still provide excellent antipolymerant activity in a monomer-containing composition.

Described are methods and compositions for inhibiting polymerization of a monomer (e.g., styrene) composition using a hydroxylated quinone antipolymerant. The hydroxylated quinone antipolymerant can be used with little or no nitroxyl group containing antipolymerant yet still provide excellent antipolymerant activity in a monomer-containing composition.

Described are methods and compositions for inhibiting polymerization of a monomer (e.g., styrene) composition using a hydroxylated quinone antipolymerant. The hydroxylated quinone antipolymerant can be used with little or no nitroxyl group containing antipolymerant yet still provide excellent antipolymerant activity in a monomer-containing composition.

A method for manufacturing and a method for decolorizing dioctyl terephthalate are provided. The decolorizing dioctyl terephthalate includes: providing an unpurified dioctyl terephthalate; mixing the unpurified dioctyl terephthalate with a reducing agent and an adsorption medium to obtain a first decolorizing product; and mixing the first decolorizing product with a decolorizing adsorbent material to obtain a second decolorizing product. The method for manufacturing dioctyl terephthalate includes: a transesterification step, an alkaline washing and neutralization step, a redox step, a decolorization step and a stripping step; the decolorizing adsorbent material has an acid value between 0.1 and 2 mg KOH/g, a relative humidity between 2 and 10%, and a fineness between 80 and 100 cm.sup.2/g.

A method for manufacturing and a method for decolorizing dioctyl terephthalate are provided. The decolorizing dioctyl terephthalate includes: providing an unpurified dioctyl terephthalate; mixing the unpurified dioctyl terephthalate with a reducing agent and an adsorption medium to obtain a first decolorizing product; and mixing the first decolorizing product with a decolorizing adsorbent material to obtain a second decolorizing product. The method for manufacturing dioctyl terephthalate includes: a transesterification step, an alkaline washing and neutralization step, a redox step, a decolorization step and a stripping step; the decolorizing adsorbent material has an acid value between 0.1 and 2 mg KOH/g, a relative humidity between 2 and 10%, and a fineness between 80 and 100 cm.sup.2/g.