Process for purification of diphenyl carbonate for the manufacturing of high quality polycarbonate

1. A process for purifying a diaryl carbonate, comprising:

reacting an aromatic hydroxy compound with a dialkyl carbonate in the presence of a transesterification catalyst to form the diaryl carbonate;

introducing an aqueous stream to a molten stream that comprises the diaryl carbonate and a metal contaminant, wherein the molten stream comprises greater than or equal to 90 wt % of the diaryl carbonate based on the total weight of the molten stream, wherein the introducing occurs at a temperature of 120° C. to 250° C., wherein the aqueous stream reacts with the metal contaminant to form a precipitate; wherein introducing the aqueous stream to the molten stream results in introducing 100 to 8,000 ppm water based on the total composition of the molten stream;

removing the precipitate via one or both of a separation column and a filter to result in a purified diaryl carbonate;

wherein when the removing utilizes the separation column, the process further comprises:

removing a bottom stream comprising the precipitate from the separation column;

removing a top stream from the separation column;

directing a top stream first portion into the separation column and collecting a top stream second portion, wherein the top stream second portion comprises the purified diaryl carbonate.

2. The process of claim 1 , wherein the removing utilizes the separation column, and wherein the introducing occurs before the molten stream enters the separation column.

3. The process of claim 1 , wherein the removing utilizes the separation column, and wherein the introducing occurs before the top stream first portion is directed into the separation column.

4. The process of claim 1 , wherein the removing utilizes the filter.

5. The process of claim 1 , wherein the metal contaminant comprises titanium, lead, tin, zirconium, molybdenum, niobium, vanadium, iron, zinc, aluminum, yttrium, lanthanum, hafnium, tungsten, neodymium, samarium, ytterbium, copper, chromium, nickel, manganese, bismuth, or a combination comprising one or more of the foregoing.

6. The process of claim 1 , wherein greater than or equal to 90 wt % of the metal contaminant is removed based on the total weight of the metal contaminant present in the molten stream.

7. The process of claim 1 , wherein the aromatic hydroxy compound has the formula (III)

wherein n is an integer from 1 to 3 and each R 2 is independently a C 1-34 alkyl, a C 1-34 alkoxy, a C 5-34 cycloalkyl, a C 7-34 alkylaryl, a C 6-34 aryl, a halogen radical, or —COO—R′, wherein R′ is H, a C 1-34 alkyl, C 1-34 alkoxy, C 5-34 cycloalkyl, C 7-34 alkylaryl, or C 6-34 aryl.

8. The process of claim 1 , wherein the diaryl carbonate has the formula (I)

wherein n is an integer from 1 to 3 and each R 2 is independently, a C 1-34 alkyl, a C 1-34 alkoxy, a C 5-34 cycloalkyl, a C 7-34 alkylaryl; a C 6-34 aryl; a halogen radical, or —COO—R′, wherein R′ is H, a C 1-34 alkyl, a C 1-34 alkoxy, a C 5-34 cycloalkyl, a C 7-34 alkylaryl; or a C 6-34 aryl.

9. The process of claim 1 , wherein the introducing occurs in a mixing device.

10. The process of claim 1 , wherein the aromatic hydroxy compound is phenol and the diaryl carbonate is diphenyl carbonate; wherein the molten stream comprises greater than or equal to 99 wt % diphenyl carbonate based on the total weight of the molten stream.

11. The process of claim 1 , wherein the purified diaryl carbonate comprises less than or equal to 38 ppb of molybdenum; less than or equal to 38 ppb of vanadium; less than or equal to 38 ppb of chromium; less than or equal to 85 ppb of titanium; less than or equal to 425 ppb of niobium; less than or equal to 38 ppb of nickel; less than or equal to 12 ppb of zirconium; less than or equal to 12 ppb of iron, or a combination comprising one or more of the foregoing based on a total weight of the purified diaryl carbonate.

12. The process of claim 10 , wherein the purified diaryl carbonate comprises less than or equal to 38 ppb of molybdenum; less than or equal to 38 ppb of vanadium; less than or equal to 38 ppb of chromium; less than or equal to 85 ppb of titanium; less than or equal to 425 ppb of niobium; less than or equal to 38 ppb of nickel; less than or equal to 12 ppb of zirconium; less than or equal to 12 ppb of iron, or a combination comprising one or more of the foregoing based on a total weight of the purified diaryl carbonate.

13. The process of claim 10 , wherein the metal contaminant comprises iron and titanium.