primisulfuron is relatively stable around a neutral pH, but is readily hydrolysed in acidic environments. In this reaction, the primisulfuron is converted into 2-(aminosulfonyl)benzoic acid, 2-amino-4,6-(difluorometh oxy)pyrimidine and carbon dioxide.

In acidic conditions this reactions occurs quite readily where primisulfuron has a half time of 3.106 days (pH=4), whereas for neutral conditions the half time is 1086 days (pH=7), and for alkaline conditions the half time is 418.6 days (pH=10). This means that in acidic soils the primisulfuron