Phthalic anhydride, Friedel-Crafts reaction preparation

More recently, Biswas and Chatteijee have prepared polystyrene electro-philically substituted with phthalic anhydride pyromellitic diianhydride tri-mellitic anhydride and 1,2,3,4-tetrahydrophthalic anhydride by Friedel-Crafts reaction. These anhydride-modified polystyrenes have further been converted into sulfonic acid resins by conventional sulfonation reaction. The thermal stabilities of these modified polymers are comparatively better than that of unmodified polystyrene. Ion-exchange capacities also compare favourably with the polystyrene-based commercial resins. 

Pyrrolo[l,2-a]indolequinones were prepared also by cyclization reactions. One of them involves copper-catalyzed pyrolysis of 2-azido-5-methoxy-6-methyl-3-(2,4-pentadienyl)-l,4-benzoquinone to give compound 45 (87JOC3956). The second pyrrole ring was also formed from a 2-hydroxy-propyl side chain of an indolo-4,7-dione (80JOC5057). Benzo analogs were prepared in a Friedel-Crafts reaction from either phthalic anhydride (67TL765) or 2-pyrrolidinylcarbonyl chloride (86H2797). 

The Friedel-Crafts reaction is an important reaction in organic synthesis and is widely used for the substitution of a side chain in an aromatic ring with AICI3 as catalyst. The reaction between benzene and phthalic anhydride, which constitutes a step in the preparation of anthraquinone, is one such reaction. We give below the chemist s and the chemical engineer s ways of looking at this reaction (see Rose, 1981, for a detailed discussion). ... 

The statine-like moiety in one of the first drugs, saquinovir (23-8), comprises a transition state mimic for the cleavage of phenylalanylprolyl and tyrosylprolyl sequences. Constmction starts with the protection of the amino group of phenylalanine as its phthaloyl derivative (Phth) by reaction with phthalic anhydride this is then converted to acid chloride. The chain is then extended by one carbon using a Friedel-Crafts-like reaction. The required reagent (21-2) is prepared by reaction of the enolate obtained from the /7A-silyl ether (21-3) of glyoxylic acid and lithio... 

Preparation from Phthalic Acid.—In discussing phthalic acid (p. 691) we spoke of the fact that phthalic anhydride or phthalyl chloride with phenol yields phenolphthalein. The reaction takes place in the presence of anhydrous zinc chloride as a dehydrating agent or in the presence of aluminium chloride (Friedel-Craft). Phthalyl chloride being the unsymmetrical compound (p. 692), the two reactions are represented as follows ... 

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