High-purity carboxylic acid ester and method for producing same

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).

1 . A high-purity carboxylic acid ester, wherein 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 wherein an anionic impurity content is less than 1 ppm. 
     
     
         2 . A method for producing a high-purity carboxylic acid ester, the method comprising: bringing a crude carboxylic acid ester that contains anionic impurities and at least Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn and Zn as metal impurities into contact with a cation-exchange resin (II); and subsequently bringing the crude carboxylic acid ester into contact with an anion-exchange resin (III). 
     
     
         3 . The method for producing a high-purity carboxylic acid ester according to  claim 2 , which comprises bringing the crude carboxylic acid ester into contact with an anion-exchange resin (I) before bringing the crude carboxylic acid ester into contact with the cation-exchange resin (II). 
     
     
         4 . The method for producing a high-purity carboxylic acid ester according to  claim 2 , wherein the carboxylic acid ester is at least one selected from the group consisting of methyl lactate, ethyl lactate, propyl lactate, methyl α-hydroxyisobutyrate, ethyl α-hydroxyisobutyrate, propyl α-hydroxyisobutyrate, butyl α-hydroxyisobutyrate, methyl β-hydroxyisobutyrate, ethyl β-hydroxyisobutyrate, propyl β-hydroxyisobutyrate and butyl β-hydroxyisobutyrate. 
     
     
         5 . The method for producing a high-purity carboxylic acid ester according to  claim 2 , wherein in the obtained high-purity carboxylic acid ester, 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. 
     
     
         6 . The method for producing a high-purity carboxylic acid ester according to  claim 2 , wherein in the crude carboxylic acid ester, the Ag, Al, Au, Ca, Cr, Cu, Fe, K, Mg, Na, Sn and Zn contents as metal impurity contents are each 8 ppb or more and the anionic impurity content is 20 ppm or more.