压差法测定异氰酸盐的水解速率常数

Determination of Hydrolysis Rate Constant of Isocyanate by Differential Pressure Method

提出了压差法测定异氰酸盐的水解反应速率常数的方法。异氰酸盐硅烷与水反应生成氨气和二氧化碳,氨气经2 mol·L^(-1)硫酸溶液吸收,采用U型压力计测量二氧化碳引起的压力变化。结果表明:异氰酸盐硅烷的浓度为0.006 mol·L^(-1)和0.010 mol·L^(-1)时,水解反应中压力的增加值与反应时间呈线性关系,至反应达到完成的时间依次为30,38 min,相关系数分别为0.992 8和0.984 9。根据试验数据算得异氰酸盐硅烷水解反应速率常数为0.102 s^(-1),半衰期为6.8 min。

Differential pressure method was proposed for determination of hydrolysis rate constant of isocyanate. Carbon dioxide and ammonia are generated by the reaction of tetraisocyanato-silane and water. Ammonia was absorbed by 2 mol·L^-1 H2SO1 solution and the raise of pressure due to carbon dioxide was measured by U manometer. It was found that in testing for the hydrolysis of tetraisocyanato silane with its concentrations of 0. 006 mol·L^-1 and 0. 010 mol·L^-1 , magnitude of increase of pressure kept linear relationship with the time of reaction which attained to an equilibrium point at 30 min and 38 rain respectively, denoting the completion of hydrolysis. Values of correlation coefficients found were 0. 9.92 8 and 0..984 9 respectively. On the base of the experimental data, hydrolysis rate constant of tetraisocyanato-silane was found to be 0. 102 s^-1 with its half-life of 6.8 min.