Phthalic acid, Tetrachloro

Phthalic acid, tetrachloro-. SeeTetrachlorophthalic acid Phthalic anhydride... 

Synonyms 1,3-Benzenedicarboxylic acid, 3,4,5,6-tetrachloro- Phthalic acid, tetrachloro- 3,4,5,6-Tetrachloro-1,2-benzenedicarboxylic acid Empirical CsHjCLO,... 

Phthalic acid, tetrabromo-, disodium salt. See Disodium tetrabromophthalate Phthalic acid, tetrachloro-. See Tetrachlorophthalic acid Phthalic anhydride... 

Highly substituted or hindered aromatic dibasic acids like tetrachloro phthalic acid and naphthalic add fail to undergo the Schmidt reaction. ... 

Hydroxyphthalazin-l(2//)-one is obtained in a smooth reaction between phthalic anhydride and hydrazine hydrate and this is again the starting compound for many 1-substituted and/or 1,4-disubstituted phthalazines. The transformations of 1,4-dichloro-phthalazine, which is prepared in the usual manner, follow a similar pattern as shown for pyridazines in Scheme 110. On the other hand, phthalonitrile is the preferential starting compound for amino- and hydrazino-phthalazines. The most satisfactory synthesis of phthalazine is the reaction between a,a,a, a -tetrachloro-o-xylene and hydrazine sulfate in sulfuric acid (67FRP1438827), alt iough catalytic dehalogenation of 1-chloro- or 1,4-dichloro-phthalazine or oxidation of 1-hydrazinophthalazine also provides the parent compound in moderate yield. 

The most efficient synthesis is based on the reaction of phthalic anhydride with the sodium salt of the pyrrole the intermediate acid after cyclization generally provides high yields of 206 and/or its substituted derivatives. Tetrachloro derivative 212 was prepared from tetrachlo-rophthalic anhydride via acid 211 by this procedure [90JCS(P 1) 1463 ]. 

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],... 

While S n reactions of the anhydride group are common, Sy reactions of substrates in which the anhydride group activates an aromatic ring are rarely reported. It is of interest therefore that 3-azidophthalic acid and tetrazidophthalic acid have been obtained by reaction of azide ion with 3-nitro- and tetrachloro-phthalic anhydride respectively . 

Retention of ester groups. Equimolar amounts of startg. nitrile and tetrafluorophthalic acid heated at 135° for 4 days in a heavy-walled glass pressure tube product. Y 56%. Work-up is simple since no solvent is required. F.e.s. W.D. Rounds, G.W. Gribble, Tetrahedron Letters 29, 6557-60 (1988) from carboxylic acid amides with tetrachloro-or tetrafluoro-phthalic anhydride s. ibid. 6553-6. 

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