THE TETRAHEDRAL INTERMEDIATE FROM THE HYDRATION OF N-METHYLFORMANILIDE

Heats of hydrolysis of N-methylformanilide dimethyl acetal have been m easured in basic solution. The heat of formation of N-methylformanilid e was obtained by determining the equilibrium constant in aqueous solu tion for its formation from formic acid and N-methylaniline as a funct ion of temperature: Delta H-f(0)(I) = -33.78 +/- 1.85 kcal/mol. These data permit the calculation of the heat of formation of N-methylforman ilide dimethyl acetal, Delta H-f(0)(I) = -72.95 +/- 1.85 kcal/mol. The free energy of formation of the tetrahedral intermediate in the hydro lysis of N-methylformanilide was calculated by methods we have previou sly reported. Consideration of the energetics of the intermediates and the known rates of reaction leads to the conclusion that the rate-det ermining step for alkaline hydrolysis is cleavage of the C-N bond.