Synthesis Of Acylaminoindoaniline Blue Dyes

Indoaniline dyes were widely used as a kind of blue-green dyes, which had important applications in development, thermal sublimation transfer, nonlinear optical materials, ion selection and near-infrared field. Acylaminoindoaniline dyes were a class of very important indoaniline dye; therefore synthesis of excellent acylaminoindoaniline dyes in a low-cost way had a very important significance.In this article, a series of carbonyl chloride were synthesized from thionyl chloride and corresponding carboxylic acid. The carbonyl chloride reacted with o-aminophenol to get a series of N-substituted o-aminophenol. And then the N-substituted o-aminophenol reacted with4-N,N-diethylaminoaniline hydrochloride in the presence of potassium ferricyanide, to give acylaminoindoaniline blue dyes. The processes were optimized, and the highest total yield of acylaminoindoaniline dyes could reach to76.8%. Otherwise, the highest total yield of one-pot method could reach to62.9%.The melting points of the acylaminoindoaniline dyes were between107-168℃. The UV/VIS spectra maximum absorption wavelength of acylaminoindoaniline dyes were between584-624nm in ethyl acetate, and the molar absorption coefficient were between17760-27230L·mol-1·cm-1. The maximum absorption wavelength of acylaminoindoaniline dyes was not affected by the influence of space steric effect, but increased along with the enhancement of electron-withdrawing ability of acylamino group. The molar absorption coefficient was increased along with the enhancement of space steric effect and electron-withdrawing ability of acylamino group. In addition, the isomers of acylaminoindoaniline dyes were proved through1H-NMR and LC-MS, and the proportion of isomers was mainly influenced by space steric effect.