Aspartate synthesis, cost

Assumptions Synthesis of phenylpyruvic acid Batch synthesis process for precursors overal yield of 95+% of theoretical to pheny Ihydantoin overall yield of 90+% of theoretical from phenylhydantoin to phenylpyruvic acid recovery and recycle of acetic acid no byproduct crec taken for acetic acid formed from acetic anhydride addition. Conversion of phenylpyruvic acid and aspartic acid. Bioreactor productivity of-18 g PHE/L/h (four columns in parallel) 98% overall conversion no byproduct credit taken for pymvic acid (recovery cost assumed to be of by revenue from sale) 80% recovery of L-PHE downstream of bioreactor. 

In the second method, dehydroaspartame is used as an intermediate, which was devised to deal with the issue of the higher cost of (Z)-phenylalanine as compared to (Z)-aspartic acid [12], The route involves synthesis of an iV-protected dehydroaspartame from (Z)-aspartic acid, benzaldehyde, and glycine. This intermediate is asymmetrically hydrogenated over a chiral rhodium catalyst to yield >90% of an (L, Z)-intermediate, which is then deprotected and separated from the < 10% of corresponding (L,D)-diastereomer by recrystallization. The yield is about 65% of product that is 99.5% pure by HPLC. 

Due to the necessity to resolve a racemic mixture, the traditional chemical synthesis of L-aspartic acid is very costly. An alternative would be to use a chiral catalyst that would selectively synthesize the L-enantiomer or one that would eliminate the D-enantiomer. Some of the most useful chiral catalysts provided by nature are enzymes. 

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