30 октября, 2015 
Pokraskin In a moisture-tight, three-necked flask provided with stirrer, thermometer, and reflux condenser, 101 grams (0.5 mole) of pyrene is dissolved at 130°C. in 1500 grams of dry trichlorobenzene (or dichloro — benzerie). A stream of dry chlorine is introduced with vigorous stirring
until the increase in weight reaches 65 grams. Toward the end of the reaction, the tetrachloropyrene separates and the reaction mixture becomes a thick paste, The endpoint of the chlorination can also be determined by following the melting point of the separated tetrachloropyrene; in this case, the chlorination is stopped when the melting point of the product is 355° (corrected). The mixture is then allowed to cool and is filtered with suction, washing the product with benzene and drying it in a steam heated oven. The yield is 130 grams of crude chloro- pyrene. A pure product can be obtained in the form of colorless needles (m. p. 368°), by recrystallizing from a large volume of nitrobenzene.
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