MGDA Synthesis via Enantiomeric Alanine and Strecker Process
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Solution Overview
Problem
Current processes for synthesizing methyl glycine diacetic acid (MGDA) and its alkali metal salts often result in impurities, such as nitrilotriacetic acid, which are undesirable due to potential cancerogenic properties, and do not achieve high purity levels.
Innovation Solution
A process involving reacting an aqueous slurry of alanine with an enantiomeric excess of at least 60% with formaldehyde and hydrocyanic acid, followed by saponification with an alkali metal hydroxide, omitting the crystallization step, to produce MGDA and its alkali metal salts with excellent purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a crystallization step is included in the synthesis process, then the purity of MGDA can be improved, but the process complexity and production time increase
Solution Approach 1:
The invention extracts and eliminates the crystallization step from the synthesis process. By using enantiomerically pure alanine as starting material and optimizing the Strecker synthesis conditions, the process achieves high purity MGDA without requiring the intermediate crystallization purification step, thus reducing process complexity while maintaining product purity
Solution Approach 2:
The invention performs preliminary action by using enantiomerically pure alanine (with enantiomeric excess of at least 60%) as the starting material before the Strecker synthesis. This preliminary selection of chiral purity prevents the formation of unwanted enantiomers and impurities during the reaction, eliminating the need for subsequent crystallization to achieve pure product
2Manufacturing precision
If multiple synthesis steps including crystallization are used, then product purity improves, but production time and productivity decrease
Solution Approach 1:
The crystallization step is completely removed from the synthesis pathway. The process goes directly from Strecker synthesis of alanine-bisacetonitrile to saponification to obtain pure MGDA, reducing the number of steps and overall production time while maintaining high purity through the use of enantiomerically pure starting materials
Solution Approach 2:
The invention enables continuous production by eliminating the intermediate crystallization and isolation steps. The process flows continuously from reaction of enantiomerically pure alanine with formaldehyde and HCN, through saponification with alkali metal hydroxide, to final pure MGDA product, maximizing productivity without sacrificing purity
3Quantity of substance
If racemic alanine is used as starting material, then material cost decreases, but product purity and enantiomeric excess decrease
Solution Approach 1:
The invention performs preliminary action by selecting and using enantiomerically pure alanine (with enantiomeric excess of at least 60%, preferably L-alanine) as the starting material before the Strecker synthesis. This preliminary chiral selection ensures that the optical purity is preserved throughout the synthesis and transferred to the final MGDA product, achieving high enantiomeric excess without requiring racemate resolution
Solution Approach 2:
The invention changes the key parameter of starting material chirality from racemic to enantiomerically enriched. By using alanine with controlled enantiomeric excess (at least 60%, preferably 95-99.5% L-alanine), the process parameters are optimized to maintain and transfer this chirality through the Strecker synthesis and saponification steps, resulting in MGDA with corresponding high enantiomeric purity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process effectively produces MGDA and its alkali metal salts with high purity, avoiding the need for crystallization and minimizing impurities, thereby enhancing the quality of the final product.
Implementation Method 1
a double Strecker synthesis is carried out by treating the aqueous slurry of said alanine with formaldehyde and hydrocyanic acid
Implementation Method 2
saponifying the alanine-bisacetonitrile from step (a) by combining the aqueous solution obtained in step (a) with an aqueous solution of alkali metal hydroxide
Data Source
AI summary
A process for making a complexing agent with an enantiomeric excess of at least 60%, wherein said process comprises the following steps: (a) reacting an aqueous slurry of alanine with an enantiomeric excess of at least 60% with formaldehyde and hydrocyanic acid, thereby forming an aqueous solution of alanine- bisacetonitrile, (b) saponifying the alanine-bisacetonitrile from step (a) by combining the aqueous solution obtained in step (a) with an aqueous solution of alkali metal hydroxide.