The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 13, 2021
Filed:
May. 21, 2019
Shin-etsu Chemical Co., Ltd., Tokyo, JP;
Yuki Suka, Joetsu, JP;
Yuji Harada, Joetsu, JP;
Shiori Nonaka, Joetsu, JP;
Kazuomi Sato, Joetsu, JP;
Takeru Watanabe, Joetsu, JP;
Takehiko Ishii, Nagareyama, JP;
SHIN-ETSU CHEMICAL CO., LTD., Tokyo, JP;
Abstract
The present invention is a method for purifying an NCA, including the steps of: a) dissolving an NCA contaminated with impurities into a solvent which is a good solvent and is not a chlorinated solvent followed by stirring to precipitate an undissolved impurity to afford a suspension, b) adding an acidic filter aid having ability to trap a basic impurity to the obtained suspension followed by filtration and/or forming a fixed bed of the acidic filter aid having ability to trap a basic impurity followed by filtering the suspension to bring the suspension to be in contact with the acidic filter aid having ability to trap a basic impurity, and c) adding the obtained filtrate dropwise to a poor solvent for NCA to crystallize out the NCA in which the impurities are removed. This makes it possible to purify a low-purity NCA conveniently to afford a high-purity NCA.