Kinetics of the cyclotrimerization and cocyclotrimerization of isocyanates catalyzed with alkali metals alkoxides

Abstract

For the rate of cyclotrimerization vt of phenyl isocyanate (I) in tetrahydrofuran catalyzed with Li, Na or K tert-butoxides (A) at 30 °C, the coefficients k, a, b of the empirical relation vt = k[I]a[A]0b were determined. The same coefficients were also determined for the cyclotrimerization of ethyl isocyanate with lithium tert-butoxide as the catalyst. The composition of the products of cocyclotrimerization of ethyl and butyl isocyanate corresponds to ratios of the rates of trimerization of the individual isocyanates. With respect to the fast decay of initiator in acetonitrile, data reported in the literature on the rate of cyclotrimerization in this solvent are not real.