Investigation of the reactivity of propanil using cyclic voltammetric methods

The stability and hence the reactivity of the herbicide, propanil [N-(3,4-dichlorophenyl) propionamide], strongly depends on pH of the medium and freshness of the solution. According to cyclic voltammetric investigation, propanil is fairly stable in mixed water/ethanol medium between pH = 4 and pH = 7 for a period of ten weeks. However, in strongly acidic medium (pH = 1), its degradation which results in 3,4- dichloroaniline (3,4-DCA) follows first order kinetics with an apparent rate constant of 5.33×10^-8 s^-1, while in strongly basic medium (pH =13), it undergoes faster degradation. 3,4-DCA is electroactive and its fresh solutions mimic the behaviour of propanil after degradation. Adsorption characteristics of propanil are also pH dependent, and its main degraded product, 3,4-DCA, is irreversibly adsorbed onto glassy carbon surfaces in an extremely basic medium.

Keywords: Degradation, electrochemical, pesticides, propanil, reactivity, 3,4-dichloroaniline  

doi:10.4038/jnsfsr.v36i3.155  

Journal of the National Science Foundation of Sri Lanka 36 (3) 199-203