Synthesis of 2,4-pyrimidinediamines

A process for preparing a compound of formula I:

• comprising:
• a) contacting an acid solvate of a compound of formula II:
• with an amide under conditions suitable for forming an amide solvate of the compound of formula II;
• and
• b) contacting the amide solvate with an aqueous base comprising sodium ions under conditions suitable for forming the compound of formula I
• wherein the carboxylic acid is R1COOH wherein R1 is —H or a C1-C4 alkyl optionally substituted with up to three halo;
• and
• the amide is R30CON(R2)2 where each R2 is independently —H or C1-C4 alkyl or both R2 together with the nitrogen to which they are attached form a 4 to 6 membered aliphatic ring, and R30 is —H or C1-C4 alkyl;
• or R30 and one of the R2 together with the carbon and nitrogen to which they are attached, respectively, combine to form a 4 to 6-membered aliphatic ring and the other R2 is independently —H or C1-C4 alkyl.