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Spectroscopic studies of the thermochromism of N ‐(2‐hydroxy‐4‐methoxybenzylidene)‐4‐nitroaniline
Author(s) -
Takase Akira,
Sakagami Sakumitsu,
aka Kazuhiro,
Koga Toshiaki
Publication year - 1993
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250240711
Subject(s) - thermochromism , orange (colour) , raman spectroscopy , melting point , chemistry , photochemistry , raman scattering , infrared , absorption spectroscopy , analytical chemistry (journal) , amine gas treating , organic chemistry , optics , physics , food science
Abstract Thermochromism of N ‐(2‐hydroxy‐4‐methoxybenzylidene)‐4‐nitroaniline (HMBNA) was studied by Raman scattering and infrared absorption. HMBNA is yellow when freshly prepared and deepens to orange–red on heating above the melting point. On cooling at room temperature, the orange–red colour is retained for a few months. The change in colour is explained by the change in the molecular structure as indicated by the vibrational spectra. The spectra show that in the thermochromic coloured state the central group of HMBNA takes the cis ‐keto amine form.