Phthalic anhydride, halogenation

Another group of halogenated fluorescein dyes is prepared by condensing chloro derivatives of phthalic anhydride with resorcinol, followed by bromination or iodination. Thus Phloxine B /78472-87-2] (Acid Red 92, Cl45410) (42) is prepared by condensing tetrachlorophthaUc anhydride with resorcinol followed by tetrabromination. Phloxine B undergoes ethylation to yield the yellowish ted acid dye Cyanosine B [6441-80-1] (43). 

Halogenated indanthrones provide improved resistance to hypochlorite treatments and many derivatives have been examined. Direct halogenation of indanthrone leads to substitution at the 7-, 8-, 16- and 17-positions. The commercially important 7,16-dichloroindanthrone (6.72 Cl Vat Blue 6) can be synthesised by a rather lengthy route from phthalic anhydride and chlorobenzene (Scheme 6.13). Polycyclic vat dyes of this type also find use as electrophotographic photoreceptors. 

The list of suitable substituents includes acylamino groups, but especially halogen atoms such as chlorine or bromine. Halogenated derivatives are obtained from tetrahalogen phthalic anhydride or naphthalene-2,3-dicarboxylic anhydride, by... 

Pigment Yellow 138,56300, has the chemical structure 138 with X = C1 [4], The synthesis of halogenated compounds (138), for instance P.Y.138, can also be achieved by stepwise heating of tetrachloro phthalic anhydride and 8-amino-chinaldine in molten benzoic acid from 125 to 140 and then to 160°C [5],... 

Uses Intermediate for phthalic anhydride, naphthol, 1,4-naphthoquinone, 1,4-dihydro-naphthalene, 1,2,3,4-tetrahydronaphthalene (tetralin), decahydronaphthalene (decalin), 1-nitro-naphthalene, halogenated naphthalenes, naphthol derivatives, dyes, explosives mothballs manufacturing preparation of pesticides, fungicides, detergents and wetting agents, synthetic resins, celluloids, and lubricants synthetic tanning preservative emulsion breakers scintillation counters smokeless powders. 

In addition to oxidation and reduction reactions, naphthalene readily undergoes substitution reactions such as nitration, halogenation, sulfonation, and acylation to produce a variety of other substances, which are used in the manufacture of dyes, insecticides, organic solvents, and synthetic resins. The principal use of naphthalene is for the production of phthalic anhydride, CgbLO,. 

Chlorobenzene is employed in the synthesis of certain amino-containing vat dye intermediates. When reacted with phthalic anhydride, the product is 2-chloroanthraquinone, which, with ammonia, is converted readily into 2-aminoanthraquinone (61). Other routes include replacement of halogen by amino groups, with ammonia or ammonium salts of urea, and alkyl- and aryl amines to afford secondary amines. Modification of the amino group by alkylation, with dimethyl sulfate, alkyl halides or esters of toluenesul-fonic acids, is of synthetic value. Arylation of the amino groups is of importance only in the reaction between aminoanthraquinones and nitro- or chloroanthraquinones to yield dianthraquinonylamines, or anthrimides48. For example, the reaction between 62 and 63 yields 64, which can then be converted into carbazole 65, Cl Vat Brown R (Scheme 14). Amination of haloanthraquinones such as l-amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) (66), prepared from 1-aminoanthraquinone, is of industrial use. 

In furtherance of studies on the synthetic utility of 2,3-dihaloindoles, Gribble reports a facile preparation of 2,3-diiodo-AI-methylindole (144) from 2-iodoindole (141). Furthermore, upon halogen-metal exchange, a relatively stable 2,3-dilithio species 145 can be generated and undergo subsequent reactions with various electrophiles such as DMF, CIC02Me, CO2, and phthalic anhydride <01TL2949>. 

Cross-linked epoxy resins are combustible and their burning is self-supporting. They require mainly reactive flame-retardants, such as tetrachloro- or tetrabromobisphenol-A and various halogenated epoxides. Even the cross-linking agent may be flame-retardant, as in the case of chlorendic anhydride, tetrabromo- or tetrachloro-phthalic anhydride, or possibly phosphorus compounds. Halogenated agents can be supplemented with antimony trioxide. 

The phthalocyanines, as copper, cobalt and nickel complexes, discovered in the 1920 s, form a versatile group of pigments they display high color-fastness with blue to green shades, depending on the degree of halogen substitution. Phthalocyanines can be produced by the widely-used synthesis from phthalic anhydride and urea as well as from phthalodinitrile. 

Phenol and its derivatives are known to form phthaleins with phthalic anhydrides and the products are very well known acid-base indicators. With maleic anhydride, a variety of phenols have been examined by Webster and Kamstra, including halogenated phenols and aminophenols while using anhydrous stannic chloride and sulfuric acid as catalysts. Although indicator properties of some were shown, no rigorous structure proof or yield data were given. Maleins 146 were reported to have formed. 

About 10% of phthalic anhydride production goes into miscellaneous uses such as the synthesis of various dyes and pigments, halogenated anhydrides, and so on. 

The halogenation of certain aromatic substrates in the presence of chlorosulfonic acid may be controlled by the experimental conditions thus phthalic anhydride may be either chlorinated or iodinated as shown in Scheme 1. 

Substitution reactions of thiophenoxides (208) with nitro- and halogeno-phthalimide derivatives (209) and with nitro- and halogen-substituted phthalic anhydrides (210) have been studied. These have given rise to a series of previously unknown thioether imides (211) and a wide range of thioether-substituted anhydrides (212). 

The above-shown bis(3-aminophenyl-)phenylphosphine oxide was used also as a reactive additive in halogen-free flame-retarded epoxy resins. Polyimides were derived from a bis(3-aminophenyl)-4-(4-adamantylphenoxy-)phenylphosphine oxide and bis(anhydrides) by polycondensation, utilizing two units of phthalic acid anhydride as end-groups (Scheme 50). ... 

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