Katsuji Matsunaga

Photochromism of 1-phenoxyanthraquinones

Abstract The photochromic phenomenon of 1-phenoxyanthraquinone (1) was investigated by IR and nuclear magnetic resonance (NMR) spectroscopy and decay of the colored species. On the basis of the spectral data the benzene ring of the phenoxyl group in the colored species was concluded to orientate with the carbonyl group within the molecule. From the kinetic analysis of the decay of the colored species, the consecutive production of two colored species, X1 and X2 (X1 → X2), was elucidated. The activation enthalpies of the reversion process from X1 to 1 and of the process from X1 to X2 were evaluated to be 8.9 and 43.2 kJ mol−1 respectively. The low activation enthalpy of the reversion process suggests that the structure of X1 is a rotational isomer of 1. X2 is assigned as a structural isomer, 9-phenoxy-1,10-anthraquinone.

Thermochromism of dyes on silica gel

1-Hydroxyanthraquinone derivatives and some pH indicators showed thermochromism on silica gel, based on the shift in the acid-base equilibrium. In a lower temperature range, the degree of acid dissociation of the dyes increased with a rise in temperature, mainly based on the increase in the basic sites on silica gel resulting from the decreasing amount of water adhering on it. In a higher temperature range, on the other hand, the acid dissociation of the dyes with a rise in temperature was promoted by the increase in acidity of the dyes.

Solvent effects in urethane formation.

The spontaneous reaction of phenyl isocyanate with 1-butanol was carried out in various solvents. The second-order rate constants for urethane formation were correlated, to a certain extent, to the dielectric constant and the polarity parameter of solvents. Although it was investigated whether the rate constants have correlations to the solubility parameter and th e h ydrogen-bonding one of solvents, the existence of a well-defined linear relationship between them was not observed.