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AssigneeDSM Fine Chemicals Austria NFG GmbH & Co KG
InventorsPeter Pochlauer, Herbert Mayrhofer
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Process for the preparation of optically highly pure (R)— and (S)—α-hydroxycarboxylic acids, in which either isolated, impure (R)— and (S)—α-hydroxycarboxylic acids prepared by acidic hydrolysis of the (R)— and (S)—cyanohydrins obtained by enzyme-catalyzed addition of a cyanide group donor to the corresponding aldehydes or ketones are recrystallized in an aromatic hydrocarbon, optionally in the presence of a cosolvent, and optically highly pure (R)— and (S)—α-hydroxycarboxylic acids having an optical purity of over 98%ee are obtained or the hydrolysis solution obtained by acidic hydrolysis of the (R)— and (S)—cyanohydrins is treated directly with an aromatic hydrocarbon, optionally in combination with a cosolvent, and is then extracted at hydrolysis temperature, whereupon after cooling of the organic phase the corresponding chemically and optically highly pure (R)— and (S)—α-hydroxycarboxylic acids having an optical purity of over 98%ee crystallize out.
A process for the preparation of optically and chemically highly pure (R)— and (S)—α-hydroxycarboxylic acids, which comprises recrystallizing impure (R)— and (S)—α-hydroxycarboxylic acids, prepared by acidic hydrolysis of the (R)— and (S)—cyanohydrins obtained by enzyme-catalyzed addition of a cyanide group donor to the corresponding aldehydes or ketones, in an aromatic hydrocarbon, optionally in the presence of a cosolvent, and obtaining optically and chemically highly pure (R)— and (S)—α-hydroxycarboxylic acids having an optical purity of over 98%ee.
The process for the preparation of chemically and optically highly pure (R)— and (S)—α-hydroxycarboxylic acids, which comprises treating the hydrolysis solution obtained by acidic hydrolysis of the (R)— and (S)—cyanohydrins, prepared by enzyme-catalyzed addition of a cyanide group donor to the corresponding aldehydes or ketones, directly with an aromatic hydrocarbon, optionally in combination with a cosolvent, then extracting the mixture at hydrolysis temperature, whereupon after cooling of the organic phase the corresponding chemically and optically highly pure (R)— and (S)—α-hydroxycarboxylic acids having an optical purity of over 98%ee crystallize out.
Dependencies are inferred from the claim text.