Nonactivated Arylazoindolinobenzospiropyran Derivatives. Part 2 1 : Preparation and Kinetic Measurements of the Spiro-ring Formation from the Merocyanine Form

摘要

Non-activated indolinobenzospiropyrans, 6-(p-substituted phenylazo)-1`,3`,3`-trimethylspiroindolinobenzopyrans(1-4) have been synthesized by the reaction of commercially available Fischer`s base with 2-hydroxy-5-arylazobenzaldehyde (S1-S4). The arylazosalicylaldehydes were obtained from the diazocoupling reaction of substituted anilines with salicylaldehyde. The rate of spiro-ring formation from the open form of these nonactivated spiropyran derivatives at room temperature has been investigated utilizing the stopped-flow method de-veloped earlier. Half life times (t1/2) of the ring-closure reaction in ethanol are about 0.3-14 seconds for the nonactivated spiropyrans examined. UV-Visible absorption spectral data of the open merocyanine form of nonactivated spiropyrans, which showed no chromotropism at room temperature, have also been obtained.