Лако-красочные материалы — производство

Spirooxazine compounds are useful in the field of plastic lenses, such as sunglasses and ski goggles. The plastic photochromic sunglasses have been in the marketplace since the early 1980s, and their market share is presently ca. 70%. The excellent lightfastness of the spironaphthooxazine series makes such applications possible, compared to other photochromic compounds. Although spironaphthooxazines […]

Spirooxazines are generally colorless compounds whose absorption bands lie in the UV region, and show photochromism in solution, plastic resin, and films. The quantum yield of the photocoloration of spiroindo- linonaphthooxazine in ethanol is very high (>0.90). In contrast to spiro- pyrans, the photocoloring reaction of spironaphthooxazine proceeds via an excited singlet state. For photocoloring […]

The absorption band of the colored form of spironaphthooxazine has been measured in thermal equilibrium with the spiro form, particularly in a polar solvent at low temperature. Typical absorption spectra of the colorless and the colored form in polymer films are shown in Figure 1.8. Figure 1.8. Absorption spectra of (a) the colorless form and […]

Spironaphthooxazines are generally prepared by condensation of 2- alkylidene heterocyclic compounds with an o-nitrosonaphthol in methanol or ethanol, as shown in Scheme 18.73 o-Nitrosonaphthol is prepared by reaction of P-naphthol with sodium nitrite in aqueous solution.74 Similarly, 5-nitroso-6-quinoline, 9-nitroso-10- phenanthol, and other o-nitroso arylols useful for the preparation of spirooxazine derivatives, have been prepared.72 Only […]

1.3.1. Introduction Spirooxazine is an aza analogue of spiropyran in which the carbon atom at 3-position is replaced by a nitrogen atom. Historically, the photo­chromic phenomenon of spiroindolinooxazine derivatives was found after discovery of photochromic spiroindolinobenzopyran.72 Spironaphthooxazine 33 is commercially available as a photochromic compound. Due to its excellent lightfastness, many spironaphthooxazines have been synthesized […]

Many 2,2-dialkylchromenes, e. g., gambogic acid and flemingins, have been discovered in nature.48 2,2-Dialkylchromenes exhibit photochromic behavior, and their colored forms generally show yellow to orange hue.57 The chromene structure is thermally stable at room temperature, and the colored form is produced by irradiation in approximately 50s in toluene at 24°C.58 Studies on the mechanism […]

Spirodibenzopyrans are prepared by two principal routes: (A) conden­sation of two equivalents of salicylaldehyde with appropriate ketone; (B) condensation of o-hydroxystyryl ketone 15, which is prepared from salicylal­dehyde and a ketone in the presence of KOH, with the same or different salicylaldehyde derivatives, as shown in Scheme 10.2,48 Spirodibenzopyran can also be obtained from 1,5-bis(2-hydroxypheny1)-1,4-pentadiene […]

1.2.2.1. Introduction A number of spirobenzopyranobenzopyrans, 14, in which two ben — zopyran components are linked via 2-spiro carbon, were prepared in the 1960s and 1970s.1,48 These compounds are also called spirodibenzopyrans or dichromenes, and they exhibit photochromic properties (Scheme 9). Four geometrical isomers for colorless forms can theoretically exist for spirodi­benzopyrans having different substituent […]

Applications of photochromic materials take advantage of a specific color change, and are found especially in the field of decorations, such as textiles and paints.1,2 The systems that utilize reverse coloration of photochromic compound are sunglasses, car windows, windowpane, infor­mation storage, and display media. Light sensitivity of photochromic materials is much lower than that of […]

The spiropyran gives the colored merocyanine form by photodissoci­ation of the spiro C—O bond. Generally, the ring-open reaction of spiroin — dolinobenzopyrans proceeds via the following mechanism: The weakening of the C—O bond due to photochemical activation of the л-electron system of the spiropyran (SP*)1 (Scheme 5), and the dissociation of C—O bond depends on […]