Process for the preparation of 4-alkoxy-3-hydroxypicolinic acids

摘要

4,6-Dibromo-3-hydroxypicolinonitrile may be prepared from furfural in a series of chemical steps selected from cyano-amination, amine salt formation and bromination-rearrangement. 4-Alkoxy-3-hydroxypicolinic acids may be conveniently prepared from 4,6-dibromo-3-hydroxypicolinonitrile in a series of chemical steps selected from bromo substitution, nitrile hydrolysis and halogen reduction.

主权项

1. A biphasic process for the preparation of the compound of Formula Acomprising the steps of:
a) creating a first mixture by combining together a 2-phase water-organic solvent system, an ammonia source, a cyanide source and a furan-2-aldehyde of Formula B b) separating a second mixture from the first mixture which includes the compound of Formula C as a solution in the organic solvent; c) adding an aqueous solution of a mineral acid to the second mixture to form a third mixture; d) separating a fourth mixture from the third mixture which is an aqueous mixture that includes the compound of formula D;wherein X is Br, HSO4, NO3 or H2PO4;
e) adding a brominating agent to the fourth mixture to form a fifth mixture; and f) isolating the compound of Formula A from the fifth mixture.