Kinetic study and degradation mechanism of landrin in aqueous media

The alkaline hydrolysis of landrin (2,3,5-trimethylphenyl-N-methylcarbamate) into 2,3,5-trimethylphenol was examined for various buffers and sodium hydroxide solutions ranging from pH 11.8 to 13.6. This work was carried out by reversed phase liquid chromatography and UV spectrophotometry. The positive activation entropy Delta S-not equal = +38.40 J mol(-1) K-1 and the absence of general basic catalysis indicated an E1cB hydrolytic mechanism involving the formation of methyl isocyanate. This result was confirmed by the finding that landrin fits well into Bronsted and Hammett plots, obtained for a series of substituted N-methylcarbamates whose decomposition in aqueous media was established to follow an E1cB mechanism.