Title:
【発明の名称】N-ビニルピロリドンの精製法
Document Type and Number:
Japanese Patent JP3190677
Kind Code:
B2
Abstract:
This invention relates to a process for the purification of a crude liquid N-vinylpyrrolidone product which comprises (I) product rectification by (a) subjecting said crude product containing at least 0.3 weight % of impurities to a temperature of between about 1 DEG and 5 DEG below the freezing point of said crude liquid to form a vinyl pyrrolidone crystalline phase and a liquid residue phase in a first crystallization step; (b) separating said liquid phase from said crystalline phase; (c) allowing said separated crystalline phase to warm gradually so as to liquify said crystals and (d) subjecting the liquified crystals of vinyl pyrrolidone to between 1 and 3 additional crystallization steps, each carried out by gradually cooling the liquified vinyl pyrrolidone to a temperature above that of the preceding crystallization step up to a temperature of 14.4 DEG C. so as to form additional vinyl pyrrolidone crystalline and liquid residue phases with separation of vinyl pyrrolidone crystals and liquid residue phases and liquification of vinyl pyrrolidone crystals between each additional recrystallization step, recovery of N-vinyl-pyrrolidone product from the final crystallization step and (II) collecting said separated liquid residues from each crystallization step and subjecting them, sequentially, individually or collectively, to fractional crystallization in order to recover additional amounts of purified vinyl pyrrolidone product. The present process is capable of achieving up to 99.999% purity of vinyl pyrrolidone in about 98% recovery.
Inventors:
Cohen jeffrey m
Bis Russell Bee
Bis Russell Bee
Application Number:
JP51807394A
Publication Date:
July 23, 2001
Filing Date:
January 21, 1994
Export Citation:
Assignee:
ISPE Investments, Inc.
International Classes:
C07D207/267; C07D207/26; (IPC1-7): C07D207/267
Other References:
【文献】米国特許5039817(US,A)
Attorney, Agent or Firm:
Akihide Sugimura (1 outside)