Mary Mei Chen

US Patent:

45230269, Jun 11, 1985

Filed:

Aug 26, 1983

Appl. No.:

6/526581

Inventors:

K. Ming Wan - East Brunswick NJ
Mary S. Chen - Edison NJ
Anil D. Pendse - Highland Park NJ

Assignee:

Hatco Chemical Corporation - Fords NJ

International Classification:

C07C125065

US Classification:

560163

Abstract:

N-Benzyloxycarbonyl-L-aspartic acid (Z-Asp) is synthesized by adding benzyl chloroformate to a solution of L-aspartic acid and sodium hydroxide at relatively high temperatures of 35. degree. -55. degree. C. and over a wide pH range of 9. 2-12. 0 and acidifying the sodium salt product. The Z-Asp is prepared in high yields exceeding 90% and purity of better than 99% with only a minor amount of the by-product N-benzyloxycarbonyl aspartyl aspartic acid. The Z-Asp is suitable for conversion to aspartame. Carrying out the reaction at high temperatures significantly reduces cycle time while maintaining a high yield with a low dipeptide and unreacted L-aspartic acid content.

US Patent:

45187924, May 21, 1985

Filed:

Aug 26, 1983

Appl. No.:

6/526579

Inventors:

Clay T. Chen - Edison NJ
K. Ming Wan - East Brunswick NJ
Mary S. Chen - Edison NJ

Assignee:

Hatco Chemical Corporation - Fords NJ

International Classification:

C07C125065

US Classification:

560163

Abstract:

N-Benzyloxycarbonyl-L-aspartic acid (Z-Asp) is synthesized by adding benzyl chloroformate to a solution of L-aspartic acid and sodium hydroxide at temperatures from about 5. degree. -55. degree. C. and over a wide pH range of about 9. 2 to 13. 8 in the presence of a surfactant and/or a buffer and then acidifying the reaction mixture. Carrying out the reaction in the presence of a surfactant reduces cycle time, while maintaining a high yield with low by-product content. The buffer prevents wide fluctuations in pH and minimizes localized reaction. These conditions are desirable when the reaction rate has been increased by addition of a surfactant or an increase in temperature of the reaction mixture.

US Patent:

45700150, Feb 11, 1986

Filed:

Aug 26, 1983

Appl. No.:

6/526580

Inventors:

K. Ming Wan - East Brunswick NJ
Mary S. Chen - Edison NJ
Clay T. Chen - Edison NJ

Assignee:

Hatco Chemical Corporation - Fords NJ

International Classification:

C07C12506

US Classification:

560163

Abstract:

N-Benzyloxycarbonyl-L-aspartic acid (Z-Asp) crystals several times larger than those obtained by conventional crystallization are prepared by acidifying an alkaline aqueous solution of a metal salt of Z-Asp at high temperatures of between about 20. degree. to 45. degree. C. The resulting large crystals contain less moisture and less impurities such as sodium chloride, dipeptide and benzyl alcohol, etc. than those crystals obtained at lower temperatures and they are easily processed for preparing aspartame.

US Patent:

51498677, Sep 22, 1992

Filed:

Jul 28, 1987

Appl. No.:

7/078550

Inventors:

Clay T. Chen - Metuchen NJ
Mary S. Chen - Metuchen NJ

Assignee:

Hatco Corporation - Fords NJ

International Classification:

C07C 5142

US Classification:

562486

Abstract:

The invention makes available an improved process for the crystallization and purification of a water-insoluble aromatic dicarboxylic acid, such as 2,6-naphthalenedicarboxylic acid. The process involves steps of contacting the insoluble acid with aqueous base to make a water-soluble di salt of the acid, removal of insoluble impurities to obtain a clear solution of the di salt, partial acidification of the solution by adding a water-soluble acid, holding the thus-obtained slurry of the insoluble acid and its salt for a time sufficient to allow dissolution of the initially-formed small particles of the insoluble acid and the formation of large well-formed crystals, then acidifying the slurry further to convert remaining salts to the insoluble acid, and recovering this acid. The crystallization can be accelerated by recycling product and by adding surfactants, and can be operated in a continuous mode. 2,6-Naphthalenedicarboxylic acid thus crystallized is readily dried, non-sticky, non-dusty, and of high purity.