Abstract: A method for producing a purified phthalonitrile is described. The method involves reacting ammonia, oxygen, and xylene in the presence of a catalyst to obtain a product gas containing a phthalonitrile and a cyanobenzamide and then contacting the reaction product gas with an organic solvent to obtain a collection liquid. The collection liquid is distilled by a high boiling point fraction-separating column to obtain a gas that contains the phthalonitrile and the organic solvent from the column top, and to obtain a bottom liquid that contains a cyanobenzamide from the column bottom. The bottom liquid has a phthalonitrile content of 90% by mass or less. The bottom liquid is subjected to combustion, while being kept in a liquid state, and the purified phthalonitrile is obtained by removing the organic solvent from the gas that has been obtained from the column top.

Abstract: A method for producing a high-purity carboxylic acid ester, the method including bringing a crude carboxylic acid ester that contains anionic impurities and Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn metal impurities into contact with a cation-exchange resin, followed by bringing the crude carboxylic acid ester into contact with an anion-exchange resin to obtain to provide a high-purity carboxylic acid ester in which the Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn metal impurity content are each less than 1 ppb and the anionic impurity content is less than 1 ppm.

Abstract: A method for producing a high-purity carboxylic acid ester, the method including bringing a crude carboxylic acid ester that contains anionic impurities and Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn metal impurities into contact with a cation-exchange resin, followed by bringing the crude carboxylic acid ester into contact with an anion-exchange resin to obtain to provide a high-purity carboxylic acid ester in which the Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn metal impurity content are each less than 1 ppb and the anionic impurity content is less than 1 ppm.

Abstract: A method for producing a polyamide, comprising performing melt polycondensation of a diamine component comprising xylylenediamine in an amount of 70 mol % or more and a dicarboxylic acid component comprising a linear aliphatic dicarboxylic acid having 6 to 18 carbon atoms in an amount of 70 mol % or more in the presence of a phosphorus atom-containing compound (A), wherein the decomposition temperature of the phosphorus atom-containing compound (A) is not lower than the melting point of the polyamide, and an aqueous solution of the phosphorus atom-containing compound (A) and the diamine component are added to the dicarboxylic acid component being in a molten state to perform the melt polycondensation.

Abstract: The present invention makes it possible to provide a high-purity carboxylic acid ester in which the Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn contents as metal impurity contents are each less than 1 ppb and the anionic impurity content is less than 1 ppm. The present invention also makes it possible to provide a method for producing a high-purity carboxylic acid ester, the method including a step for bringing a crude carboxylic acid ester that contains anionic impurities and Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn, and Zn as metal impurities into contact with a cation-exchange resin (II), followed by a step for bringing the crude carboxylic acid ester into contact with an anion-exchange resin (III).

Abstract: A method for producing a polyamide, comprising performing melt polycondensation of a diamine component comprising xylylenediamine in an amount of 70 mol % or more and a dicarboxylic acid component comprising a linear aliphatic dicarboxylic acid having 6 to 18 carbon atoms in an amount of 70 mol % or more in the presence of a phosphorus atom-containing compound (A), wherein the decomposition temperature of the phosphorus atom-containing compound (A) is not lower than the melting point of the polyamide, and an aqueous solution of the phosphorus atom-containing compound (A) and the diamine component are added to the dicarboxylic acid component being in a molten state to perform the melt polycondensation.

Abstract: The invention is a method for producing a polyamide having a melting point of 255° C. or higher through polycondensation of a mixed xylylenediamine containing paraxylylenediamine as a diamine component and a dicarboxylic acid component in a batch reactor, wherein when the diamine component is dropwise added to the dicarboxylic acid component kept in a melt state by heating it to a temperature not lower than a melting point thereof under a pressure of 0.1 MPaG or more with keeping the melt state of a reaction mixture, a temperature of the reaction mixture is maintained at 255° C. or lower until a molar ratio (diamine component/dicarboxylic acid component) of the reaction mixture reaches 0.8, and the temperature of the reaction mixture at the end of the dropwise addition is controlled to be not lower than the melting point of the polyamide. The method enables production of a polyamide having an improved hue and being advantageous with respect to quality.

Abstract: A crude liquid containing 1,3-bis(aminomethyl)cyclohexane and a high-boiling component having a boiling point higher than that of 1,3-bis(aminomethyl)cyclohexane is distilled. By controlling the distillation conditions, the high-boiling component is prevented from entering into a distilled 1,3-bis(aminomethyl)cyclohexane and the content of a low-boiling component in the distilled 1,3-bis(aminomethyl)cyclohexane is minimized.

Abstract: A crude liquid containing 1,3-bis(aminomethyl)cyclohexane and a high-boiling component having a boiling point higher than that of 1,3-bis(aminomethyl)cyclohexane is distilled. By controlling the distillation conditions, the high-boiling component is prevented from entering into a distilled 1,3-bis(aminomethyl)cyclohexane and the content of a low-boiling component in the distilled 1,3-bis(aminomethyl)cyclohexane is minimized.