On-line attenuated total reflection infrared (ATR-IR) spectroscopy combined with advanced chemometrics for investigating the synthesis process of 3,5-diamino-1,2,4-triazole

Abstract

The synthesis process of 3,5-diamino-1,2,4-triazole (DAT) was investigated by on-line attenuated total reflection infrared (ATR-IR) spectroscopy combined with advanced chemometrics method. The principal component analysis (PCA) was used to analyze the IR spectra matrix, which was in order to obtain orthonormal column and the number of principal components. Then the pure IR spectrum of every substance was obtained by mutual information least dependent component analysis (MILCA). The possible synthesis mechanism of DAT was deducted based on the changes of functional groups in the IR spectra. The geometric configurations of intermediates were optimized with the density functional theory (DFT) at B3LYP/6-311G*(d, p) level, and the vibrational frequencies were calculated simultaneously. The results by MILCA method agree well with quantum chemical calculation method, thus which demonstrated the reliability of MILCA. The present study proves that on-line ATR-IR spectroscopy combined with advanced chemometrics method can be applied to study the chemical synthesis mechanism and provide a strong technical support for the research and development of process analytical technology (PAT).