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

A process for the preparation of the compound of Formula A

• wherein R1 is a C1-C3 alkyl;
• from the compound of Formula B
• which comprises the following steps:
• a) creating a first mixture by combining together the compound of Formula B and a chlorinating agent;
• b) isolating a compound of Formula C from the first mixture;
• wherein R is H or Cl;
• c) creating a second mixture containing an alkali metal alkoxide of Formula D
• MOR1 D
• wherein M is Na or K, and R1 is a C1-C3 alkyl;
• and the compound of Formula C;
• d) isolating a compound of Formula E from the second mixture
• wherein R is H or Cl and R1 is a C1-C3 alkyl;
• e) creating a third mixture containing the compound of Formula E, water, and one of a mineral acid and a strong base;
• f) heating the third mixture;
• g) isolating a compound of Formula F from the third mixture
• wherein R is H or Cl and R1 is a C1-C3 alkyl;
• h) creating a fourth mixture containing the compound of Formula F and a reducing agent;
• and
• i) isolating the compound of Formula A from the fifth mixture;
• wherein R1 is a C1-C3 alkyl.