Process for the recovery of a boronic acid

A process for recovery of a boronic acid of formula R3—B(OH)2, wherein R3 is selected from the group consisting of C1-C6 linear or branched alkyl, C3-C6 cycloalkyl, and C6 aryl, optionally substituted with a group selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, t-butyl, and phenyl, from an aqueous mixture optionally comprising a polar solvent, said process comprising the following steps:

• admixing an aqueous mixture comprising a boronic acid of formula R3—B(OH)2, wherein R3 is as defined above, with a water-immiscible organic solvent in a weight ratio between the boronic acid and the water-immiscible organic solvent from 1:10 to 1:20, wherein the organic water-immiscible solvent is selected from the group consisting of 4-methyl-2-pentanone (MIBK), 3-pentanone, 2-pentanone, dibutyl ether, 2-methyl-tetrahydrofurane, cyclopentylmethyl ether, methyl isopropyl ketone, and methyl isopentyl ketone, and wherein the aqueous mixture optionally comprises a polar solvent,
• adding an aqueous solution to a final pH from 6 to 7, and
• partitioning the boronic acid into the organic water-immiscible phase and recovery of the organic water-immiscible phase.