MUMBAI, India, June 19 -- Intellectual Property India has published a patent application (202647067524 A) filed by Refine Holdings Co. , Ltd. on May 29, 2026, for Purification Method.
Inventors include Oda Akiyoshi; Kato Takamasa; and Ozeki Yuichi.
The application for the patent was published on June 05, 2026, under issue no. 23/2026.
Abstract: Provided is a purification method for N-methyl-2-pyrrolidone that makes it possible to appropriately control an addition amount for an alkali compound and also makes it possible to separate and remove water and impurities. According to the present invention, a purification method for purifying a starting material that contains N- methyl-2-pyrrolidone and water and also contains a low-boiling-point amine and a methyl succinimide as impurities includes a pH measurement step for extracting a portion of an in-column liquid from at least one of a first distillation step and a second distillation step as a pH measurement liquid, mixing the pH measurement liquid and water such that the mass ratio of the pH measurement liquid and the water is 0.5–20, and measuring the pH of the mixed liquid, a calculation step for calculating an addition amount for an alkali compound on the basis of the pH results from the pH measurement step, and an alkali addition step for adding the alkali compound to the starting material from before the first distillation step or the like in the addition amount calculated at the calculation step. The amount of water is controlled such that the mass ratio of the pH measurement liquid and the water of the mixed liquid at the pH measurement step is a constant ratio within an error of ±5%.
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