Kinetic Study of the Degradation of Ethiofencarb in Aqueous Solutions

✍ Scribed by Sanz-Asensio, Jesús; Plaza-Medina, María; Martínez-Soria, María T.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 271 KB
• Volume: 50
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/(sici)1096-9063(199707)50:3<187::aid-ps580>3.0.co;2-h

✦ Synopsis

A kinetic study of the hydrolysis of ethiofencarb (a-ethylthio-o-tolyl methylcarbamate) in pure water and in aqueous solutions at pH 2, 6, 9 and 12 and at three di †erent temperatures (4, 20 and 50(^1)¡C) has been carried out using a gas chromatographic nitrogen-phosphorus detection method. The values of the Ðrst-order rate constants (k) for the degradation reaction were calculated. The values for k were found to be dependent on pH and temperature. No acid hydrolysis was observed in any case. Complete degradation of ethiofencarb was observed at pH 12 at all three temperatures ; it was practically instantaneous at room temperature. Ethiofencarb was also completely degraded at pH 9 at 20 and 50¡C, while in pure water (pH 6) degradation took place at 50¡C but not at 20¡C. Ethiofencarb was not degraded in pure water at lower temperatures and, due to the reversible nature of the reaction, at equilibrium about 80% of the pesticide remained undegraded at room temperature.