The kinetics of hydrolysis of 4-chlorophenyi isocynate has been studied spectrophotometrically in the range of water concentrations 0.8-1.4M in dioxane solution at three temperatures.
When the ratio [H₂O] / [RNCO] is large sufficiently the final or...
The kinetics of hydrolysis of 4-chlorophenyi isocynate has been studied spectrophotometrically in the range of water concentrations 0.8-1.4M in dioxane solution at three temperatures.
When the ratio [H₂O] / [RNCO] is large sufficiently the final organic product is p-chloroaniline only, which arises from the initially formed carbamic acid, RNHCO₂H. In the presence of a sufficient excess of water, the overall process comprises two consecutive first-order reactions, whose pseudo-first order rate constants k'₁ and k'₂ both depend on the second power of the water concentration.
For the first step AH and 4S are 3. 98Kcal/mol and -57.4caI/K·mol respectively, for the second step are 3.58 Kcal/mol and -63.9 cal/K·mol.
Both the first step and second step are first-order with respect to isocyanate and second-order to water.
These results could be interpreted in terms of cyclic transition state involving dimeric water.