Лако-красочные материалы — производство

The thermal fading of the colored form follows first-order kinetics.1 The substituent effects in the pyran component obey Hammett-type corre — lation.2 For example, the value of p for the thermal fading rate of spiroin — dolinobenzopyrans having substitution only in the pyran portion is — 1.8 to — 3.45. The electron-donating group in the […]

Generally, measurement of absorption spectra of the colored form of spirobenzopyran is very difficult using normal spectrophotometry, as the colored form is thermally unstable. The absorption spectra of the colored form of 6,8-dinitro-BIPS 7, which is exceptionally stable in DMSO even at 23°C, are shown in Figure 1.4. Generally, it is possible to obtain a […]

The X-ray crystal structures of some spiroindolinobenzopyrans, e. g., 8-NO2-BIPS and 6-NO2-8-Br-BIPS, have been determined by Russian researchers.6,7 Recently, X-ray crystal structures of the colorless form (7a) and the colored form (7b) of 6,8-dinitro-BIPS have been reported by Nakatsu8 (Figure 1.3). In the colorless form (7a), the C2—O1 bond length (1.50A) is signifi­cantly longer than […]

1.1.1. Spiroindolinobenzopyran (BIPS) and Related Series 1.1.1.1. Synthesis The spiroindolinobenzopyran 2 is a classical example of spiropyran and is easily prepared by the condensation of 1,3,3-trimethyl-2-methyleneindo — line (Fischer’s base) and salicylaldehyde in anhydrous ethanol or benzene (Scheme 2).1,2 The nucleophilic attack of Fischer’s base on the carbonyl group (like an enamine) gives an aldol […]

HIROYUKI NAKAZUMI 1.1. INTRODUCTION The spiropyran is a pyran derivative linked by a common spiro carbon atom with another heterocyclic ring. Generally, the spiropyran absorbs in the UV region, but not in the visible region. On irradiation with UV light the spiropyran undergoes heterolytic cleavage of the carbon-oxygen bond to form the colored isomer, which […]

The field of dye chemistry has stimulated the publication of many books, monographs, special topics, and reviews over the years, but surprisingly, very little is mentioned about leuco dye chemistry — Color formers have been known for a long time. Many natural products are color formers and have become part of modern synthetic dyes, e. […]

Dye chemistry has seen a major resurgence of interest in recent years, as evidenced by increased conference activity and the publication of many new books in the field. This can be attributed to a virtual explosion of interest in dyes for speciality and high-technology applications (the functional dyes), and it is in these areas that […]