Described are compositions and methods for inhibiting polymerization of a monomer (e.g., styrene) composition, which use an N—O polymerization inhibitor, a quinone methide polymerization retarder, and an amine stabilizer having a primary and/or secondary amine group. In a mixture, the amine-based stabilizer can prevent antagonistic effects and can provide greater antipolymerant activity. In turn, the mixture inhibits apparatus fouling and improves the purity of monomer streams.

The present invention relates to an improved process for the preparation of 2,2′,2″-(10-((2R,3S)-1,3,4-trihydroxy butan-2-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetic acid, gadolinium (III) with iron metal content less than 5 ppm and free gadolinium content less than 10 ppm, which is represented by the formula (1). The present invention further relates to an improved process for the preparation of calcium complex of 10-(2,3-Dihydroxy-1-(hydroxymethyl)propyl)-1,4,7,10-tetraazacyclo decane-1,4,7-triacetic acid known as Calcobutrol (1a) and its sodium salt of formula (1b) with purity greater than 98.0%.

##STR00001##

The present invention relates to an improved process for the preparation of 2,2′,2″-(10-((2R,3S)-1,3,4-trihydroxy butan-2-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl) triacetic acid, gadolinium (III) with iron metal content less than 5 ppm and free gadolinium content less than 10 ppm, which is represented by the formula (1). The present invention further relates to an improved process for the preparation of calcium complex of 10-(2,3-Dihydroxy-1-(hydroxymethyl)propyl)-1,4,7,10-tetraazacyclo decane-1,4,7-triacetic acid known as Calcobutrol (1a) and its sodium salt of formula (1b) with purity greater than 98.0%.

##STR00001##

The subject-matter of the invention is process for the separation of optical isomers of racemic 3-alk-3-carboxylic acid ethyl esters of formula rac-I with the resolving agent (II) (−)-2,3:4,5-di-O-izopropylidene-2-keto-L-gulonic acid (hereinafter: diacetone-L-ketogulonic acid).

The subject-matter of the invention is process for the separation of optical isomers of racemic 3-alk-3-carboxylic acid ethyl esters of formula rac-I with the resolving agent (II) (−)-2,3:4,5-di-O-izopropylidene-2-keto-L-gulonic acid (hereinafter: diacetone-L-ketogulonic acid).

A method of stabilizing perfluoro(2-methylene-4-methyl-1,3-dioxolane) (hereinafter simply referred to as a “stabilization method”), including incorporating at least one selected from the group consisting of a hydroxy group-containing fluoroaromatic compound represented by General Formula (1) below and a hydroxy group-containing fluoroaromatic compound represented by General Formula (2) below into a composition containing perfluoro(2-methylene-4-methyl-1,3-dioxolane): ##STR00001##
(in the formula, R.sup.1 to R.sup.6 each independently represent one selected from the group consisting of a fluorine atom, a perfluoroalkyl group and a hydroxy group, and at least one of R.sup.1 to R.sup.6 is a hydroxy group); ##STR00002##
(in the formula, R.sup.7 to R.sup.14 each independently represent one selected from the group consisting of a fluorine atom, a perfluoroalkyl group and a hydroxy group, and at least one of R.sup.7 to R.sup.14 is a hydroxy group).

A method of stabilizing perfluoro(2-methylene-4-methyl-1,3-dioxolane) (hereinafter simply referred to as a “stabilization method”), including incorporating at least one selected from the group consisting of a hydroxy group-containing fluoroaromatic compound represented by General Formula (1) below and a hydroxy group-containing fluoroaromatic compound represented by General Formula (2) below into a composition containing perfluoro(2-methylene-4-methyl-1,3-dioxolane): ##STR00001##
(in the formula, R.sup.1 to R.sup.6 each independently represent one selected from the group consisting of a fluorine atom, a perfluoroalkyl group and a hydroxy group, and at least one of R.sup.1 to R.sup.6 is a hydroxy group); ##STR00002##
(in the formula, R.sup.7 to R.sup.14 each independently represent one selected from the group consisting of a fluorine atom, a perfluoroalkyl group and a hydroxy group, and at least one of R.sup.7 to R.sup.14 is a hydroxy group).

Systems for quenching peroxycarboxylic acid and peroxide chemistry runaway reactions provide safe and efficacious systems to prevent uncontrolled runaway reactions, such as decomposition reactions, of peroxycarboxylic acid and peroxide chemistry compositions are disclosed. The systems provide prompt detection and dispensing of a stabilizer into a tank or other storage vessel containing a peroxide composition, peroxycarboxylic acid composition or a peroxycarboxylic acid-forming composition to stop a runaway reaction. Methods for quenching peroxide and peroxycarboxylic acid runaway reactions are also disclosed.

Systems for quenching peroxycarboxylic acid and peroxide chemistry runaway reactions provide safe and efficacious systems to prevent uncontrolled runaway reactions, such as decomposition reactions, of peroxycarboxylic acid and peroxide chemistry compositions are disclosed. The systems provide prompt detection and dispensing of a stabilizer into a tank or other storage vessel containing a peroxide composition, peroxycarboxylic acid composition or a peroxycarboxylic acid-forming composition to stop a runaway reaction. Methods for quenching peroxide and peroxycarboxylic acid runaway reactions are also disclosed.

The invention addresses the problem of providing a method for producing 2-acetyl-4H,9H-naphtho[2,3-b]furan-4,9-dione that is suited to industrial production. The invention provides a method for producing 2-acetyl-4H,9H-naphtho[2,3-b]furan-4,9-dione by reacting 3-bromo-3-buten-2-one and 2-hydroxy-1,4-naphthoquinone in the presence of a solvent, then obtaining crystals of 2-acetyl-4H,9H-naphtho[2,3-b]furan-4,9-dione by adding an alcohol-based solvent and/or water to the reaction system, and treating the crystals by using a specific adsorbent in the presence of a solvent.