Cyanohydrination catalyst
AssigneeShell Oil Company
InventorsWalter Dong, Walter L. Petty
Life of this patent
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Abstract
A cyanohydrination catalyst for the preparation of alpha-hydroxynitriles from aldehydes and ketones comprises a solid cyclo(D-phenylalanyl-D-histidine) or cyclo(L-phenylalanyl-L-histidine) dipeptide having a non-crystalline or amorphous component.
Claims17
A process of directly preparing a solid cyclo(D-phenylalanyl-D-histidine) or cyclo(L-phenylalanyl-L-histidine) dipeptide catalyst to obtain an active catalyst for use in chiral cyanohydrination which comprises forming a substantially non-crystalline or amorphous component of at least 45% or more of the dipeptide by a method selected from (a) rapidly evaporating a solution of the catalyst;
- (b) rapidly precipitating the catalyst from a solution by dilution in a poor solvent;
- (c) freeze drying of a solution of the catalyst;
- (d) rapid cooling of a melted catalyst;
- or (e) using crystallinity inhibitors during solidification.
A process for producing a cyanohydrination catalyst of high enantiomeric selectivity which comprises forming a solid cyclo(D-phenylalanyl-D-histidine) or cyclo(L-phenylalanyl-L-histidine) dipeptide catalyst having a substantially non-crystalline or amorphous component of at least 45% or more of the dipeptide by a method selected from (a) rapidly evaporating a solution of the catalyst;
- (b) rapidly precipitating the catalyst from a solution by dilution in a poor solvent;
- (c) freeze drying of the solution of the catalyst;
- (d) rapid cooling of a melted catalyst;
- or (e) using crystallinity inhibitors during solidification.
A process for increasing the enantiomeric selectivity of a cyanohydrination catalyst which comprises forming a solid cyclo(D-phenylalanyl-D-histidine) or cyclo(L-phenylalanyl-L-histidine) dipeptide catalyst having a substantially non-crystalline or amorphous component of at least 4590 or more of the dipeptide by a method selected from (a) rapidly evaporating a solution of the catalyst;
- (b) rapidly precipitating the catalyst from a solution by dilution in a poor solvent;
- (c) freeze drying of a solution of the catalyst;
- (d) rapid cooling of a melted catalyst;
- or (e) using crystallinity inhibitors during solidification.
Dependencies are inferred from the claim text.