Phthalic Anhydride → Naphthalene

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Reaction Steps

By the process according to the present invention it has surprisingly been possible to obtain a colorless, pure phthalic anhydride with a melting point of 131.2° C., a naphthoquinone content of less than 1 ppm, and a color value of less than 10 APHA. These surprising results have been obtained by heating crude phthalic anhydride produced from naphthalene containing 0.7-0.8% by weight of naphthoquinone and 0.04% by weight of maleic anhydride, for 20 hours with, for example, 0.2% by weight of commercial polybutadiene oils to about 240° C., followed by vacuum distillation. Similar results were obtained with the use of polyisoprene, polydimethylbutadiene, and poly-1,3-pentadiene.

Provenance & Evidence