Phenyl carbamates, alkaline hydrolysis

Substituted Phenyl N-Methyl Carbamates Rate of alkaline hydrolysis in vitro (37)... 

An application of Equation (13) is illustrated in Figure 6 for the alkaline hydrolysis of substituted phenyl carbamates. Here the points for resonating para substituents lie above the line. When a" is used for these points instead of g the data obey a linear equation and r - 1. 

Figure 6 Alkaline hydrolysis of substituted phenyl carbamates (p = 3.35, r = 0.785). para substituents uncorrected , meta substituents /5., para substituents...

Wolfe et al. (1978) have developed structure-activity relationships for the hydrolysis of a number of TV-substituted and TV,TV-disubstituted carbamates. An excellent correlation was found between the second-order alkaline hydrolysis rate constant (kb) for the carbamates and the pKa of the alcohol formed upon hydrolysis. The linear free energy relationships for the TV-phenyl and TV-methyl-TV-phenyl carbamates are illustrated in Figure 2.10. These data indicate that only the TV-phenyl carbamates will hydrolyze under environmental conditions. The half-life for the hydrolysis of these chemicals will be less than 6 months at pH 8 at 25°C. 

Alkaline hydrolysis of ethiofencarb [(2-ethylthiomethyl)phenyl]-A-methyl carbamate (17), a carbamate insecticide, proceeds via an lcB mechanism (Scheme 6). ... 

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