Thioindigo

Photodegradation as well as fluorescence quenching has been observed in chlorophyll monolayers [302,316]. Whitten [317] observed a substantial decrease in the area of mixed films of tripalmitin and a ci5-thioindigo dye as isomerization to the trti 5-thioindigo dye occurred on irradiation with UV light. 

Supplement 1952 2666-3031 Carbonyl compounds Ethylene carbonate, 100. Piperonal, 116. Thioindigo, 177. Fluorescein, 222. Carboxylic acids Piperonylic acid, 269. Amines, 328. Three Cyclic Oxygens, 381. Four Cyclic Oxygens, 433. Fiite Cyclic Oxygens, 459.. . . ... 

Thioindigo Pigments. The thioindigos are red and violet pigments developed for textiles. Two red—violets. Pigment Red 88 [14295 3-3] and Pigment Red 198 [6371-39-9] are recommended for plastics because of their excellent fastness properties. 

Free Electron Molecular Orbital method colour and constitution, 1, 342 Freelingyne occurrence, 4, 706 Free radical processes in photography, 1, 387-389 Friedlander synthesis quinolines, 2, 443 thioindigo dyes, 4, 910 Fries rearrangement chroman-4-one synthesis from, 3, 850 Fructose, 1-deoxy- C NMR, 4, 575 Frusemide as diuretic, 1, 174 metabolism, 1, 245 FS-32 — see 1/f-Indazole, l-[3-... 

Thioindigo [522-75-8] M 296.2, m >280 . Adsorbed on silica gel from CCl4/ benzene (3 1), eluted with benzene, crystd from CHCI3 and dried at 60-65°. [Wyman and Erode J Am Chem Soc 73 1487 1951.] This paper also gives details of purification of other thioindigo dyes. 

A unique example of observation of tunneling splitting is given by Oppenlander et al. [1989]. Upon replacing the host benzoic acid dimer by a thioindigo molecule of nearly the same size, the resulting bias accidentally turns out to be small, of order of A. The 4x4 Hamiltonian of the complex of two dimers and the guest molecule is... 

Fig. 40. Flole-burning spectra of thioindigo in benzoic acid crystal at 1.35 K. The scanning laser frequency cu is measured with respect to the burning laser frequency cUb is detuning of the burning laser frequency relative to the center of absorption line.

Thioindigo hydroaddiert Kohlendioxid, Acrylnitril sowie Zimtsaure-nitril mit guten Ausbeuten6 ... 

By analogy with anthracene, dioxygenation of dibenzothiophene produces 2-hydroxyben-zothiophene-3-carboxaldehyde, and this may be transformed into a number of products including benzothiophene-2,3-dione and further into disulfides and thioindigo (Bressler and Fedorak 2001a,b). 

Thiohydrazides, 13 575 colorant for plastics, 7 374t Thioindigo pigments, 19 444 Thioindoxyl... 

The chemical classes of vat colours from which suitable pigments have been developed are anthraquinones, perinones, perylenes and thioindigos. Many vat dyes have been tested, but only about a dozen have met the stringent fastness standards demanded. Seven of those found suitable in all respects are shown in Table 2.1 and their chemical structures are given as 2.4 to 2.10. 

Most pigments derived from vat dyes are structurally based on anthraquinone derivatives such as indanthrone, flavanthrone, pyranthrone, or dibromoan-thanthrone. There are other polycyclic pigments which may be used directly in the form in which they are manufactured. This includes derivatives of naphthalene and perylene tetracarboxylic acid, dioxazine (Carbazole Violet), and tetrachloro-thioindigo. Quinacridone pigments, which were first introduced in 1958, and recently DPP pigments have been added to the series. 

In this section a number of polycyclic pigments are discussed which have been used for a long time as vat dyes for textile fibers. Heading the list are perylene, perinone, and thioindigo pigments, as well as pigments derived from anthraquinone. 

Thioindigo pigments have the following general structure ... 

Oxidation may be achieved in the presence of oxygen or air. Other suitable oxidants include sulfur, sodium polysulfide, iron (III) chloride, potassium ferro-cyanide (III) or potassium dichromate, peroxydisulfate or salts of aromatic nitro-sulfonic acids. An aqueous/alkaline medium is used in the presence of a high boiling organic solvent which is not miscible with water or which is almost immiscible with water. Cyclization with chlorosulfonic acid can be followed directly by oxidation with bromine to afford the thioindigo system, without separation of the intermediate. 

Although there is one route [3] which describes the direct synthesis of the tetrachlorothioindigo pigment by oxidation of 3-hydroxy-4,7-dichlorothionaphthenone with oxygen in an aqueous alkaline medium, this is somewhat of an exception. In most cases, it is necessary to modify the crude thioindigo derivative by appropriate aftertreatment in order to develop the desired pigment properties. 

Thioindigo pigments provide a range of hues from red violet and maroon to brown shades. The type and position of the substituents affects the shade ... 

Unsubstituted thioindigo, which is marketed as Vat Red 41, 73300, is used in rigid PVC, polystyrene, and a number of other plastics. Dissolved in its medium, the pigment affords fluorescent bluish red shades. 

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