1.2.4- dioxazines

Inositols, ie, hexaliydrobenzenehexols, are sugars that have received increasing study and are useful in the treatment of a wide variety of human disorders, including vascular disease, cancer, cirrhosis of the Hver, frostbite, and muscular dystrophy (269). Myoinositol esters prepared by reaction with lower fatty acid anhydrides are useful as Hver medicines and nonionic surfactants the aluminum and ammonium salts of inositol hexasulfate are useful anticancer agents (270). Tetraarjloxybenzoquinones are intermediates in the preparation of dioxazine dyes (266,271). The synthesis of hexakis(aryloxy)benzenes has also beenpubUshed (272). 

Dioxazine Violet. Carba2ole Dioxa2ine Violet is prepared by the reaction of two moles of 2-ainino-A/-ethylcarba2ole with chloranil. This violet may be used in most plastics for shading phthalocyanine blues, because it has comparable light fastness. At relatively high temperatures, it may be subject to slow decomposition. 

Trifluoromethyl-substituted dioxazine or pyrimidine derivatives are obtained oriK3.cliQn oihexafluoroacetone with cyanoguanidines [93] orcyanoacetamides... 

The reaction of a cepham primary amine with 20 eq. of 37% formalin produces the dioxazine in 75% yield. The dioxazine is sufficiently stable to allow the formation of Wittig reagents and to carry out an olefination with formaldehyde. Treatment of the dioxazine with 6 N HCl in CH2CI2 releases the amine in excellent yield. ... 

Bis(trifluoromethyl)-substituted 1,3-heterodienes are a rich source of heterocycles through cycloadditions, for example, with ketenes (86CZ83) and azirines [89JFC(42)51] to give dioxazines and triazepines, respectively. 

In the case of aromatic amines there is an initial nucleophilic substitution catalyzed by the silanol groups of the silica gel layer to yield arylaminobenzoquinone derivatives, that undergoe oxidative cyclization to the corresponding dioxazines [1]. 

The chemistry of the three most important chemical classes of organic colorants, the azo, carbonyl and phthalocyanine classes, has been dealt with individually in Chapters 3-5 respectively. In this chapter, the chemistry of a further five chemical classes which are of some importance for specific applications is discussed. These classes are the polymethines, arylcarbonium ion colorants, dioxazines, sulfur dyes and nitro dyes. A section of this chapter is devoted to each of these, each individual section contains a description of the principal structural features which characterise the particular colorant type, together with an outline of the chemistry of the main synthetic routes. There are many other chemical types of dyes and pigments that do not fall into the categories previously mentioned, but which are neglected in this text either because they are commercially of little importance or because they have been less extensively investigated. 

In the synthetic scheme, 3-amino-9-ethylcarbazole 138 (2 mol) is condensed with chloranil 137 (1 mol) to form the intermediate 139. This intermediate is then converted into the dioxazine pigment 136 by oxidative cyclisation at around 180 °C in an aromatic solvent and in the presence of a catalyst such as aluminium(m) chloride or benzenesulfonyl... 

Other chemical types of high-performance organic pigments are exemplified by the tetrachloroisoindolinone 222 (C. I. Pigment Yellow 110) and the dioxazine 223 (Carbazole Violet, C. I. Pigment Violet 23). Considerable research has been carried out in an attempt to exploit the potential of metal complex chemistry to provide high-performance pig-... 

A mixture of nitrones (142) and dioxazines (143) forms from a mixture of Z-and E -isomers of oximes (141), obtained from acetonide of erythrulose (140). The reaction is carried out in a mixture of acetone and 2,2-dimethoxypropane, in the presence of catalytic quantities of TsOH (Scheme 2.51) (305). 

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