Synthesis of acid hydrazides using flow chemistry

A continuous process for preparing a compound of Formula (III)

• or a salt and/or solvate thereof, the process comprising:
• (a) forming a first reaction stream comprising a compound of Formula (I) dissolved in an alcohol;
• (b) flowing the reaction stream from step (a) through a continuous flow reactor at a temperature of about 100° C. to about 160° C. and at a flow rate of about 0.2 mL/min to about 5 mL/min;
• (c) contacting the reaction stream from step (b) with a second reaction stream comprising a hydrazine source to form a combined reaction stream;
• and
• (d) flowing the combined reaction stream from step (c) through a continuous flow reactor at a temperature of about 100° C. to about 160° C. and at a flow rate of about 0.2 mL/min to about 5 mL/min;
• wherein
• R1 is Y or
• R3 is Y or
• Y is an aryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl group;
• Z is a divalent group selected from arylene, heteroarylene, alkylene, cycloalkylene, and heterocycloalkylene groups;
• and
• R1 and R3 are both Y, or R1 and R3 are both not Y.