Purification of bisphenol-A

• US 4,447,655 A
• Filed: 11/24/1982
• Issued: 05/08/1984
• Est. Priority Date: 11/24/1982
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Mendiratta, Ashok K.
• Primary Examiner(s): Hart, Charles N.
• Assistant Examiner(s): Ledbetter, Jr., Titus B.
• Application Number:
  US06/444,103
• Time in Patent Office: 531 Days
• Field of Search: 210/634, 210/742, 210/804, 210/806, 422/271, 422/272, 568/724, 568/750
• US Class Current: 568/724
• CPC Class Codes: C07C 37/685 Processes comprising at least two steps in series
• CPC Class Codes: C07C 37/84 by crystallisation
• CPC Class Codes: C07C 39/16 Bis-(hydroxyphenyl) alkanes; Tris-(hydroxyphenyl)alkanes
• CPC Class Codes: C07C 39/36 Pentachlorophenol

Abstract

An efficient method of purifying bisphenol-A is presented whereby solvent washing of the bisphenol-A crystals and extraction of impurities, bisphenol-A and phenol from the aqueous liquid of a water/bisphenol-A crystal slurry is accomplished simultaneously and in a continuous operation. The method involves contacting the water/bisphenol-A crystals with an organic washing solvent in a continuous, multi-stage, countercurrent extraction column.

Claims

1. A process for simultaneously and continuously purifying the bisphenol-A crystals and the aqueous liquid of a water/BPA crystals slurry, said process comprising the steps of:

(a) forming an aqueous-crystal stream from a water/BPA crystals slurry, said aqueous-crystal stream having a flow which is substantially downward and continuous;

(b) contacting said aqueous-crystal stream with a stream comprising an organic solvent in a region of intersecting paths, the stream of organic solvent having a flow in a direction substantially upward and counter-current to the flow of said aqueous crystal stream, said organic solvent being immiscible in water, lighter than water and a good solvent medium for impurities within said aqueous liquid and bisphenol-A crystals;

(c) mixing the aqueous-crystal stream and the organic solvent stream passing through the region of contact in the center of said region of contact;

(d) forming a lower aqueous-crystal phase below the the region of contact and an upper organic solvent phase above the region of contact;

(e) recovering purified bisphenol-A crystals and purified aqueous liquid from said lower aqueous-crystal phase;

(f) removing organic solvent with extracted impurities from said upper organic solvent phase;

said process being performed at a temperature below the melting point of said bisphenol-A crystals.

2. A process for simultaneously and continuously purifying the bisphenol-A crystals and the aqueous liquid of a water/BPA crystals slurry, said process comprising the steps of:

(a) forming an aqueous-crystal stream from a water/BPA crystals slurry, said aqueous-crystal stream having a flow which is substantially downward and continuous;

(b) contacting said aqueous-crystal stream with a stream comprising an organic solvent in a region of intersecting flow paths, the stream of organic solvent having a flow in a direction substantially upward and counter-current to the flow of said aqueous-crystal stream, said organic solvent being immiscible in water, lighter than water and a good solvent medium for impurities within said aqueous liquid and bisphenol-A crystals;

(c) mixing the aqueous-crystal stream and the organic solvent stream passing through the region of contact in multiple isolated portions of said region of contact;

(d) forming two small intermediate phases between each isolated mixing portion, the intermediate phase pairs comprising an aqueous crystal phase and an organic solvent phase;

(e) forming a lower aqueous-crystal phase below said region of contact and an upper organic phase above said region of contact;

(f) recovering purified bisphenol-A crystals and purified aqueous liquid from said lower aqueous crystal phase, and

(g) removing organic solvent with extracted impurities from said upper organic solvent phase,

said process being performed at a temperature below the melting point of said bisphenol-A crystals.

3. A process in accordance with claim 2 wherein the organic solvent utilized to form said organic solvent stream is toluene.

4. A process in accordance with claim 2 wherein the temperature at which said process is performed is selected from a value within the range of 40°

C. to 85°

C.

5. A process in accordance with claim 2 wherein one half part of organic solvent is utilized to form said organic solvent stream for every part of the bisphenol-A crystals within said water/BPA crystal slurry to be purified on a weight basis.

6. A process in accordance with claim 2 further comprising the step of separating said purified bisphenol-A crystals from said lower aqueous-crystal phase.

7. A process in accordance with claim 6 further comprising the step of crystallizing crude bisphenol-A in the purified aqueous liquid of said lower aqueous-crystal phase.