Three phase crystallization of bisphenol A

• US 4,079,087 A
• Filed: 01/27/1969
• Issued: 03/14/1978
• Est. Priority Date: 01/27/1969
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Sun, Yun Chung
• Primary Examiner(s): Morgenstern, Norman
• Application Number:
  US04/794,375
• Time in Patent Office: 3,333 Days
• Field of Search: 260/619 A
• US Class Current: 568/723
• CPC Class Codes: C07C 15/08 Xylenes
• CPC Class Codes: C07C 15/14 all phenyl groups being directly linked
• CPC Class Codes: C07C 15/24 containing two rings
• CPC Class Codes: C07C 37/84 by crystallisation
• CPC Class Codes: C07C 39/16 Bis-(hydroxyphenyl) alkanes; Tris-(hydroxyphenyl)alkanes
• CPC Class Codes: C07C 7/14 by crystallisation; Purification or separation of the crystals

Abstract

A process for purifying a crude crystalline or crystallizable water-immiscible aromatic compound contaminated with one or more related congeneric impurities which cannot be readily separated by distillation, said process comprising:

1. forming a dispersion of liquefied crude material in an aqueous liquid by agitating the mixture;

2. effecting crystallization of the desired aromatic compound while maintaining the dispersion;

3. reducing agitation sufficiently to permit the formation of three phases, i.e., a solid crystalline phase, an aqueous liquid phase, and a mother liquor phase; and

4. separating the crystals;

Said aqueous liquid being immiscible with, and having a density between, the aforementioned solid crystalline phase and the mother liquor phase.

Claims

1. A process for purifying a crude bisphenol A compound from a mixture containing at least 25 weight percent of said compound, contaminated with one or more related cogeneric impurities which cannot be readily separated by distillation, said process comprising:

1. forming a dispersion of liquefied crude bisphenol A in chlorobenzene in an inert immiscible aqueous 20% solution of sodium chloride by agitating a mixture of the two wherein said aqueous liquid is substantially immiscible with both the bisphenol A, and the mother liquor phase composed of the liquid impurities and chlorobenzene containing the liquid impurities, and the said aqueous liquid has a density between (a) and (b),

2. effecting crystallization of the bisphenol to be purified while maintaining the dispersion;

3. centrifuging the mixture to permit the formation of three phases, i.e., a solid crystalline phase, an aqueous liquid phase, and a mother liquor phase, said aqueous liquid phase having sufficient height to completely separate the crystalline and mother liquor phases; and

4. separating the crystals from step (3) without contact between the crystals and mother liquor.