Degradation via hydrolysis is among the main transformation pathways and particularly for N‐methylcarbamates. Carbamate pesticide hydrolysis is known to proceed through alkaline catalysis, with reaction of the hydroxide ion with the carbonyl function or with abstraction of hydrogen in the α position with respect to the carbonyl. This reaction leads to the formation of methylamine and corresponding phenol. In this respect, the reaction kinetics of 4‐bromo‐3,5‐dimethylphenyl N‐methylcarbamate (BDMC) hydrolysis have been investigated in alkaline solution using a spectrophotometric technique and reversed phase liquid chromatography. The kinetic constants were determined following a proposed pseudo–first‐order kinetic model. The positive activation entropy ΔS^≠ = +35.73 J mol⁻¹ K⁻¹ and the absence of general base catalysis indicated an unimolecular elimination conjugate base (E1cB) hydrolytic mechanism involving the formation of methyl isocyanate. This result was confirmed by the fact that BDMC fits well into brönsted and Hammett lines, obtained for a series of substituted N‐methylcarbamate whose decomposition in aqueous media was established to follow an E1cB mechanism.

中文翻译：

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介质中4-溴-3,5-二甲基苯基N-甲基氨基甲酸酯的动力学研究及其机理水解

水解降解是主要的转化途径之一，尤其是对于N-甲基氨基甲酸酯。已知氨基甲酸酯农药的水解是通过碱催化进行的，其中氢氧根离子与羰基官能团反应或相对于羰基的α位氢被夺取。该反应导致形成甲胺和相应的苯酚。在这方面，已使用分光光度法和反相液相色谱法研究了碱性溶液中4-溴-3,5-二甲基苯基N-甲基氨基甲酸酯（BDMC）水解的反应动力学 。根据提出的拟一级动力学模型确定动力学常数。正激活熵ΔS ^≠＝ + 35.73J mol ^-1 K ^-1，并且不存在一般的碱催化表明存在形成异氰酸甲酯的单分子消除共轭碱（E1cB）水解机理。BDMC很好地适合了Brönsted和Hammett品系，这一事实证实了BDMC，它是由一系列取代的N-甲基氨基甲酸酯获得的，其在水性介质中的分解遵循E1cB机理。