Hydrochloric Acid → p-Phenylene benzobisoxazole

Beteiligte Stoffe

Reaktionsschritte

In the apparatus described under Example 1, 21.8 g of reactant A (0.2 mol), 25.8 g of p-trichloromethyl-benzoyl chloride (0.1 mol) and 3.5 g of B2O3 (0.05 mol) were mixed and slowly heated. Between 190° and 200° C, a vigorous evolution of HCl began. After 2 hours the mixture was cooled and ground in a mortar. After extraction twice with 100 ml of CHCl3 and twice with 100 ml of water, 22.3 g of raw product (71% of the theory) was obtained, melting at 318° to 328° C. Compound XIX can be recrystallized from dimethylformamide, o-dichlorobenzene, nitrobenzene, dimethylsulfoxide or 1,2-dibromoethane. A small specimen recrystallized from o-dichlorobenzene melted at 325° to 329° C. The product can be further purified by chromatography on Al2O3 with 1,2-dibromoethane as the elutant at 120° C, whereupon the melting point becomes 340° to 342° C.

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