3,4,5,6-Tetrachlorophthalic anhydride

Fluorination of tetrachlorophthalic acid hemihydrate with an excess of sulfur tetrafluoride, or of tetrachlorophthalic anhydride with a sulfur tetrafluonde-hydro-gen fluoride reagent, provides an efficient synthesis of 4,5,6,7- tetrachloro-1,1,3,3-tetrafluorol,3-dihydroisobenzofuran. 3,4,5,6-Tetrachloro-2-(trifluoromethyl)-benzoyl fluoride is formed as a by-product [217] (equation 111). 

Cyclization of 3,4,5,6-tetrachlorophthalic anhydride (8) in the presence of urea, Ihe appropriate metal salt and catalytic amounts of ammonium molybdate(VI) in nitrobenzene at high temperature leads to phthalocyanine 9. 

The pyrolysis of a number of compounds at temperatures around 600— 800° and at pressures of the order of 10 2 mm. has been shown to give rise to benzyne. These compounds include for example indanetrione 29>, and phthalic anhydride 30 38>. The dimerisation of benzyne to yield biphenylene has been used preparatively 31 33>, an(j the pyrolysis of tetrafluorophthalic anhydride 34>, and tetrachlorophthalic anhydride 3i-33) gave the corresponding octahalobiphenylenes. In the case of the pyrolysis of tetrachlorophthalic anhydride some hexachlorobenzene is also formed, while the pyrolysis of tetrabromophthalic anhydride results in the formation of hexabromobenzene but no octabromobiphenylene. The disproportionation of tetrabromobenzyne to form carbon and bromine is a function of the high temperature involved and, as we shall see later, both tetrabromo- and tetraiodo-benzyne behave normally in solution. 

Howe W et al Tetrachlorophthalic anhydride asthma Evidence for specific IgE antibody. J Allerg Clin hrnnun 71 5-11, 1983... 

Flaherty DK, Gross GJ, Winzenburger P, et al In vitro immunologic studies on a population of workers exposed to phthalic and tetrachlorophthalic anhydride. J Occup Med 30 785-790, 1988... 

Fluorination of tetrachlorophthalic acid with sulfur tetrafluoride alone or of tetrachlorophthalic anhydride with a sulfur tetrafluoride/hydrogen fluoride mixture provides an efficient synthesis... 

A one-step reaction between tetrachlorophthalic anhydride (22) and potassium fluoride in an autoclave at 300 r C affords a mixture of perfluoroanthraquinone (23) besides hexa- and hepta-fluoro derivatives. The mixture can be converted to 23 by reacting it with spray-dried potassium fluoride in tetramethylene sulfone at 150°C.114... 

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 [18472-87-2] (Acid Red 92, Cl45410) (42) is prepared by condensing tetrachlorophthalic anhydride with resorcinol followed by tetrabromination. Phloxine B undergoes ethylation to yield the yellowish red acid dye Cyanosine B [6441 -80-1] (43). 

Proton donors may be present or formed at the beginning of copolymerization and are necessary for the formation of primary active centres. In such a case, initiation according to Fischer s mechanism 39,40 (Eq. (37)) does not take place. Although the formation of a zwitterion (betaine-like structure) supports the possibility of the generation of charge-transfer complexes between cyclic anhydrides and amines, which may yield betaine-like structures82), simple anhydrides are much weaker ti acceptors than the often employed tetrachlorophthalic anhydride. 

A 45% yield of copper 3,4,5-trichlorophthalocyanine-4, 4",4m-sulfonic acid is made from 3.5g 4-sulfophthalic acid, 3.4g tetrachlorophthalic anhydride (molar ratio 1 1), 0.5g copper powder, 10 g urea, lmL titanium tetrachloride, and 0.5 g iodine, heated for 2 hr at 210°C. The yield is 3.1 g and the product is moderately water-soluble. 

Cava et al. (1966) passed the vapors of phthalic and tetrachlorophthalic anhydride over a glowing Niehrome coil at 800° at 50 torr, and trapped the pyrolysate on a cold finger kept at —78°. Phthalic anhydride gave 10-15% biphenylene, based on unrecovered anhydride tetrachlorophthalic anhydride gave 30% perchlorobiphenylene. In view of the findings of Lindow and Friedman (1967), these products probably were accompanied by tetraphenylene and its derivatives. 

Tetrachlorophthalic anhydride gave a relatively low yield of products derived from tetrachlorobenzyne. The pyrolysis tube was badly carbonized evidently extensive decomposition of the anhydride, the aryne, or the chlorinated products had occurred. Tetrabromophthalic anhydride gave a still lower yield of products. These are not listed in the table because none of them retained all four bromine atoms and could be definitely ascribed to reactions of tetrabromobenzyne, although tri-bromo- and dibromonaphthalene were present in appreciable amounts. Tetraphenylphthalic anhydride also gave low yields of products of the reaction of tetraphenylbenzyne with pyridine. This was not because of the stability of the anhydride and its reluctance to form the aryne, but rather because the aryne preferred to stabilize itself intramolecularly. The behavior of tetraphenylphthalic anhydride is discussed in another Section. 

Tetrachloronaphthalene (26) and tetrachlorobenzothiophene (27) from tetrachlorophthalic anhydride formed by addition of tetrachloro-benzyne to thiophene and subsequent loss of sulphur and acetylene, respectively (Fields and Meyerson, 1967e) ... 

The main reactive flame-retardant compounds used in unsaturated polyesters are tetrabro-mophthalic anhydride, dibromoneopentyl glycol, bis(2-hydroxyethyl) ether of tetrabromobisphenol A, and chlorendic anhydride. Tetrachlorophthalic anhydride is also used. 

Like phenolphthalein, xanthene dyes are prepared in a condensation reaction involving phthalic anhydride. However, resorcinol is employed instead of phenol. The simplest representative of this family is C.I. Acid Yellow 73 (fluorescein), which is made via the sequence of steps shown in Fig. 13.109. Similarly, C.I. Acid Red 92 is made by the condensation of tetrachlorophthalic anhydride and resorcinol followed by bromination. 

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