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US 9,428,437 B2Granted
Method for dehydrating alpha-substituted carboxylic acids
AssigneeEvonik Roehm GmbH
InventorsAlexander May, Steffen Krill, Joerg Becker, Willi Ploesser, Marcel Treskow, Martin Koestner
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Abstract
The present invention describes a process for preparing alpha-beta-unsaturated carboxylic acids by dehydration of hydroxycarboxylic or alkoxycarboxylic acids which are substituted in the alpha position, in particular 2-hydroxyisobutyric acid, while avoiding accumulation of by-products and additives.
Claims13
A process, comprising:
- feeding a reaction stream comprising an alpha-substituted carboxylic acid into a reaction circuit,
- feeding a catalyst stream comprising a catalyst into the reaction circuit,
- dehydrating the alpha-substituted carboxylic acid in the reaction circuit in the presence of a polymerization inhibitor, to obtain a product stream comprising water, an alpha-beta-unsaturated carboxylic acid, unreacted alpha-substituted carboxylic acid, and the polymerization inhibitor, wherein at least part of the product stream is continuously discharged from the reaction circuit,
- separating the polymerization inhibitor and the alpha-beta-unsaturated carboxylic acid from the unreacted alpha-substituted carboxylic acid, and reintroducing the unreacted alpha-substituted carboxylic acid into the reaction circuit.
1 more element
Dependencies are inferred from the claim text.